SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

5.4.7 EARTHQUAKE

This section provides a profile and vulnerability assessment for the earthquake hazard.

HAZARD PROFILE

This section provides profile information including description, extent, location, previous occurrences and losses and the probability of future occurrences.

Description

An earthquake is the sudden movement of the Earth’s surface caused by the release of stress accumulated within or along the edge of the Earth’s tectonic plates, a volcanic eruption or by a manmade explosion (FEMA, 2001; Shedlock and Pakiser, 1997). Most earthquakes occur at the boundaries where the Earth’s tectonic plates meet (faults); however, less than 10 percent of earthquakes occur within plate interiors. New Jersey is in an area where plate interior-related earthquakes occur. As plates continue to move and plate boundaries change over geologic time, weakened boundary regions become part of the interiors of the plates. These zones of weakness within the continents can cause earthquakes in response to stresses that originate at the edges of the plate or in the deeper crust (Shedlock and Pakiser, 1997).

The location of an earthquake is commonly described by its focal depth and the geographic position of its epicenter. The focal depth of an earthquake is the depth from the Earth’s surface to the region where an earthquake’s energy originates (the focus or hypocenter). The epicenter of an earthquake is the point on the Earth’s surface directly above the hypocenter (Shedlock and Pakiser, 1997). Earthquakes usually occur without warning and their effects can impact areas of great distance from the epicenter (FEMA, 2001).

According to the U.S. Geological Society (USGS) Earthquake Hazards Program, an earthquake hazard is anything associated with an earthquake that may affect resident’s normal activities. This includes surface faulting, ground shaking, landslides, liquefaction, tectonic deformation, tsunamis, and seiches. A description of each of these is provided below.  Surface faulting: Displacement that reaches the earth's surface during slip along a fault. Commonly occurs with shallow earthquakes, those with an epicenter less than 20 kilometers.  Ground motion (shaking): The movement of the earth's surface from earthquakes or explosions. Ground motion or shaking is produced by waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the earth and along its surface.  Landslide: A movement of surface material down a slope.  Liquefaction: A process by which water-saturated sediment temporarily loses strength and acts as a fluid, like when you wiggle your toes in the wet sand near the water at the beach. This effect can be caused by earthquake shaking.  Tectonic Deformation: A change in the original shape of a material due to stress and strain.  Tsunami: A sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands.  Seiche: The sloshing of a closed body of water from earthquake shaking (USGS, 2012).

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Extent

Seismic waves are the vibrations from earthquakes that travel through the Earth and are recorded on instruments called seismographs. The magnitude or extent of an earthquake is a measured value of the earthquake size, or amplitude of the seismic waves, using a seismograph. The Richter magnitude scale (Richter Scale) was developed in 1932 as a mathematical device to compare the sizes of earthquakes (USGS, 1989). The Richter Scale is the most widely-known scale that measures the magnitude of earthquakes (Shedlock and Pakiser, 1997; USGS, 2004). It has no upper limit and is not used to express damage. An earthquake in a densely populated area, which results in many deaths and considerable damage, may have the same magnitude and shock in a remote area that did not cause any damage (USGS, 1989). Table 5.4.7-1 presents the Richter Scale magnitudes and corresponding earthquake effects.

Table 5.4.7-1. Richter Scale Richter Earthquake Effects Magnitude 2.5 or less Usually not felt, but can be recorded by seismograph 2.5 to 5.4 Often felt, but only causes minor damage 5.5 to 6.0 Slight damage to buildings and other structures 6.1 to 6.9 May cause a lot of damage in very populated areas 7.0 to 7.9 Major earthquake; serious damage 8.0 or greater Great earthquake; can totally destroy communities near the epicenter Source: USGS, 2006

The intensity of an earthquake is based on the observed effects of ground shaking on people, buildings, and natural features, and varies with location. Intensity is expressed by the Modified Mercalli Scale; a subjective measure that describes how strong a shock was felt at a particular location (Shedlock and Pakiser, 1997; USGS, 2004). The Modified Mercalli Scale expresses the intensity of an earthquake’s effects in a given locality in values ranging from I to XII. Table 5.4.7-2 summarizes earthquake intensity as expressed by the Modified Mercalli Scale. Table 5.4.7-3 displays the Modified Mercalli Scale and peak ground acceleration equivalent.

Table 5.4.7-2. Modified Mercalli Intensity Scale Mercalli Description Intensity I Felt by very few people; barely noticeable.

II Felt by few people, especially on upper floors.

III Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake.

IV Felt by many indoors, few outdoors. May feel like passing truck. Felt by almost everyone, some people awakened. Small objects moves, trees and poles may V shake. Felt by everyone; people have trouble standing. Heavy furniture can move, plaster can fall off walls. VI Chimneys may be slightly damaged. People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks VII fall from buildings. Damage is slight to moderate in well-built buildings; considerable in poorly built buildings. Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Some walls VIII collapse. Considerable damage to specially built structures; buildings shift off their foundations. The ground IX cracks. Landslides may occur.

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Mercalli Description Intensity Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are X seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, lakes. The ground cracks in large areas. Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground. XI Underground pipelines are destroyed. Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or XII ripples. Large amounts of rock may move. Source(s): Michigan Tech University, 2007; Nevada Seismological Laboratory, 1996

Table 5.4.7-3. Modified Mercalli Intensity (MMI) and PGA Equivalents

Acceleration (%g) MMI (PGA) Perceived Shaking Potential Damage I < .17 Not Felt None II .17 – 1.4 Weak None III .17 – 1.4 Weak None IV 1.4 – 3.9 Light None V 3.9 – 9.2 Moderate Very Light VI 9.2 – 18 Strong Light VII 18 – 34 Very Strong Moderate VIII 34 – 65 Severe Moderate to Heavy Source: NYS HMP, 2011

Modern intensity scales use terms that can be physically measured with seismometers, such as the acceleration, velocity, or displacements (movement) of the ground. The most common physical measure is Peak Ground Acceleration (PGA). PGA expresses the severity of an earthquake and is a measure of how hard the earth shakes, or accelerates, in a given geographic area. PGA is expressed as a percent acceleration force of gravity (%g). For example, 1.0 g PGA in an earthquake (an extremely strong ground motion) means that objects accelerate sideways at the same rate as if they had been dropped from the ceiling. 10% g PGA means that the ground acceleration is 10% that of gravity (NJOEM, 2011). Damage levels experienced in an earthquake vary with the intensity of ground shaking and with the seismic capacity of structures as noted in Table 5.4.7-4.

Table 5.4.7-4. Damage Levels Experienced in Earthquakes Ground Motion Explanation of Damages Percentage Motions are widely felt by people; hanging plants and lamps swing strongly, but damage 1-2% g levels, if any, are usually very low. Below 10% g Usually cause only slight damage, except in unusually vulnerable facilities. May cause minor to moderate damage in well-designed buildings, with higher levels of 10-20% g damage in poorly designed buildings. At this level of ground shaking, only unusually poor buildings would be subject to potential collapse. May cause significant damage in some modern buildings and very high levels of damage 20-50% g (including collapse) in poorly designed buildings. May causes higher levels of damage in many buildings, even those designed to resist seismic 50% + g forces. Source: NJOEM, 2011

According to USGS Earthquake Hazards Program, PGA maps (also known as earthquake hazard maps) are used as planning tools when designing buildings, bridges, highways, and utilities so that they can withstand shaking associated with earthquake events. These maps are also used as planning tools for the development of building codes that establish construction requirements appropriate to preserve public safety.

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The USGS updated the National Seismic Hazard Maps in 2008 which superced the 2002 maps. New seismic, geologic, and geodetic information on earthquake rates and associated ground shaking were incorporated into these revised maps. The 2008 map represents the best available data as determined by the USGS (USGS, 2008). Figure 5.4.7-1. 2008 Seismic Hazard Map, PGA with 10% Probability of Exceedance in 50 Years

Source: USGS, 2008 Note: The red circle indicates the approximate location of Somerset County. The figure indicates that the County has PGA of 3-4%g

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Figure 5.4.7-2. 2002 Seismic Hazard Map, PGA with 10% Probability of Exceedance in 50 Years

Source: USGS, 2002 Note: The red circle indicates the approximate location of Somerset County. The figure indicates that the County has PGA of 3-4%g

The 2002 Seismic Hazard Map shows that Somerset County has a PGA between 3 and 4%g (Figure 5.4.7- 2). The 2008 Seismic Hazard Map shows that Somerset County has a PGA between 3 and 4%g (Figure 5.4.7-1). These maps are based on peak ground acceleration (%g) with 10% probability of exceedance in 50 years.

In addition to magnitude and intensity, local soil type can substantially affect an earthquake’s risk. The National Earthquake Hazard Reduction Program (NEHRP) developed five soil classifications that impact the severity of an earthquake. The soil classification system ranges from A to E, where A represents hard rock that reduces ground motions from an earthquake and E represents soft soils that amplify and magnify ground shaking and increase building damage and losses [Tantala et al. (NYCEM), 2003]. As illustrated in Figure 5.4.7-3, Somerset County is comprised of seismic soil classes B through E. The majority of the County is soil classs C; however, class D soils are located along riverine reaches.

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Figure 5.4.7-3. Seismic Soils in Somerset County

Source: NJOEM, 2011 Note: The black circle indicates the location of Somerset County. The County mainly consists of Class C soils, with narrow bands of Class D and small locations of Class B and Class E. Table 5.4.7-5. NEHRP Soil Classifications

Soil Classification Description Map Color A Very hard rock (e.g., granite, gneisses) Green B Sedimentary rock or firm ground Yellow C Stiff clay Orange D Soft to medium clays or sands Light Pink E Soft soil including fill, loose sand, waterfront, lake bed clays Red Source: FEMA, 2007

A probabilistic assessment was conducted for the 100-, 500- and 2,500-year mean return periods (MRP) through a Level 2 analysis in HAZUS-MH 2.1 to analyze the earthquake hazard for Somerset County. The HAZUS analysis evaluates the statistical likelihood that a specific event will occur and what consequences will occur. Figure 5.4.7-4 through Figure 5.4.7-6 illustrates the geographic distribution of PGA (g) across Somerset County or 100-, 500- and 2,500-year MRP events at the Census-tract level.

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Figure 5.4.7-4. Peak Ground Acceleration Modified Mercalli Scale for a 100-Year MRP Earthquake Event

Source: HAZUS 2.1 Note: The peak ground acceleration for the 100-year MRP is 0.84 to 1.28 %g.

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Figure 5.4.7-5. Peak Ground Acceleration Modified Mercalli Scale for a 500-Year MRP Earthquake Event

Source: HAZUS 2.1 Note: The peak ground acceleration for the 500-year MRP is between 4.32 and 6.4 %g

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Figure 5.4.7-6. Peak Ground Acceleration Modified Mercalli Scale for a 2,500-Year MRP Earthquake Event

Source: HAZUS 2.1 Note: The peak ground acceleration for the 2,500-year MRP is between 16.68 and 23.56 %g.

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Location

The U.S., east of the Rocky Mountains, typically has fewer and generally smaller earthquakes than the western U.S. At least two factors increase the earthquake risk in New Jersey and the eastern U.S.:

 Eastern earthquakes affect areas ten times larger than western earthquakes; and

 The eastern U.S. and New Jersey are more densely populated than the west, with New Jersey being the most densely populated state in the country.

Earthquakes typically occur in the northern parts of the State, where significant faults are concentrated. However, low magnitude events can and do occur in areas throughout the State (NJOEM, 2011). New Jersey has experienced a few small earthquakes throughout the years. Earthquake damage in New Jersey has been minor, including items knocked off shelves, cracked plaster and masonry, and fallen chimneys. These, along with earthquakes originating outside of New Jersey, have produced enough damage to be a concern of planners and emergency managers (Dombroski, 2005).

According to the New Jersey Geological Survey (NJGS), New Jersey has a similar tectonic setting as New York City, Boston, and Charleston. All three cities have experienced earthquakes with a magnitude greater than 5 on the Richter scale. Further explanation of the Richter Scale is located in the Extent section of this profile. Earthquakes of these magnitudes could occur in New Jersey. The risk of damaging earthquakes, in combination with New Jersey’s population density and building/structural value, places New Jersey as the tenth highest among all U.S. states for potential economic loss from earthquakes [Stanford (NJGS), 2003].

Many faults are located within New Jersey, including the Ramapo Fault which separates the Piedmont and Highlands Physiographic Provinces (Figure 5.4.7-7). This fault runs 70 miles northeast from Morris County, New Jersey and the Hudson Highlands to Bear Mountain, New York (Groves, 2001). The fault is a hairline fracture, 50 miles long, and is located 35 miles from New York City. Seismographic stations, part of the Advanced National Seismic System, are used to monitor earthquakes and ground motion near important buildings and critical infrastructure along this fault (Lamont-Doherty, 2004). Numerous minor earthquakes have been recorded in the Ramapo Fault zone, a 10 to 20 mile wide area lying adjacent to and west of the actual fault (Dombroski, 2005). Over 25 percent of earthquakes experienced in New Jersey over the past 200 years had their epicenters within 30 miles of this fault (Groves, 2001). In the 1970s and 1980s, earthquake risk along the Ramapo Fault was studied more in depth due to its close proximity to the Indian Point, New York Nuclear Power Generating Station.

East of the Rocky Mountains, including New Jersey, earthquake faults do not break the ground surface. Their focuses are at least a few miles below the Earth’s surface and their locations are determined by interpreting seismographic records. Geological fault lines seen on the surface today are evidence of ancient events. The presence or absence of mapped faults does not denote either a seismic hazard or the lack of one, and earthquakes can occur anywhere in New Jersey (Dombroski, 2005).

The closest plate boundary to the East Coast is the Mid-Atlantic Ridge, which is approximately 2,000 miles to the east of Pennsylvania. Over 200 million years ago, when the continent Pangaea rifted apart forming the Atlantic Ocean, the Northeast coast of America was a plate boundary. Being at the plate boundary, many faults were formed in the region. Although these faults are geologically old and are contained in a passive margin, they act as pre-existing planes of weakness and concentrated strain. When a strain exceeds the strength of the ancient fault, it ruptures causing an earthquake (Lehigh Earth Observatory, 2006).

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Figure 5.4.7-7. Physiographic Provinces of New Jersey

Source: NJGS, Date Unknown Note: Vast majority of Somerset County is located within the Piedmont Province, with only the northernmost part in the Highlands.

The Ramapo Fault (Figure 5.4.7-8) is part of a system of northeast striking, southeast-dipping faults, which runs from southeastern New York State to the Hudson River at Stony Point, through eastern Pennsylvania and beyond. The fault is a hairline fracture, 50 miles long, and is located 35 miles from New York City. Seismographic stations, part of the Advanced National Seismic System, are used to monitor earthquakes and ground motion near important buildings and critical infrastructure along this fault (Lamont-Doherty, 2004; Pasfield, Unknown). Numerous minor earthquakes have been recorded in the Ramapo Fault zone, a 10 to 20 mile wide area lying adjacent to and west of the actual fault (Dombroski, 2005).

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Figure 5.4.7-8. Ramapo Fault Line

Source: Rasmusson, 2003

Figure 5.4.7-9 and Figure 5.4.7-10 show the Ramapo Fault Line and the earthquakes that have occurred in the surrounding area of the fault.

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Figure 5.4.7-9. Ramapo Fault Line

Source: Groves, 2001

The New York Consortium for Earthquake Mitigation (NYCEM) HAZUS MH study presents the results of a multi-year study that addresses the risks of an earthquake in the New York City area. The New York City study area includes parts of northern New Jersey (including Somerset County). The study indicates a low seismic hazard (infrequent damaging earthquakes), but high seismic risk due to its dense population, concentration of buildings, vulnerable infrastructure, and substantial economic value [Tantala et al. (NYCEM), 2003]. A USGS earthquake hazard map (Figure 5.4.7-10) indicates peak ground acceleration (PGA) with a 10 percent chance of being exceeded over 50 years as highest in northeastern New Jersey, (dark yellow) (USGS, 2002). Further description of PGA is located in the Extent section of this profile.

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Figure 5.4.7-10. Earthquakes in New York City and the Surrounding Area, 1627-2003

Source: Lamont-Doherty Earth Observatory, 2004 Note: The Ramapo Fault System is shown as a red line. Hexagons indicate earthquake events prior to 1970 and circles indicate earthquakes post 1970 (when systematic earthquake monitoring began in the region). The symbol size is proportional to magnitude.

Previous Occurrences and Losses

Many sources provided historical information regarding previous occurrences and losses associated with earthquakes throughout the State of New Jersey. Therefore, with so many sources reviewed for the purpose of this HMP, loss and impact information for many events could vary depending on the sources.

According to the NJGS, there are over 150 records of earthquakes in the State, with most of them occurring in the northern portion. Most of the earthquake events that have occurred in the State have been too small to cause damage. Figure 5.4.7-11 shows the locations of these earthquakes and their corresponding magnitudes.

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Figure 5.4.7-11. Earthquakes Epicentered in New Jersey

Source: NJOEM, 2011 Note: The figure indicates that Somerset County has experienced six earthquake events.

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Table 5.4.7-16 depicts these earthquakes events. Several of these events were located within the vicinity of Somerset County.

Table 5.4.7-6. Earthquake Occurrences in the New York/New Jersey Area, 1737-2012. FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 12/19/1737 5.2 Greater NYC Area* N/A N/A Threw down chimneys Lamont-Doherty North-Central New 2 Foreshocks (11/24 and 11/30) and 1 NJGS, Lamont- 11/30/1783 5.3 N/A N/A Jersey* aftershock (11/30); threw down chimneys Doherty 1/25/1841 0.0 West Orange, NJ N/A N/A No reference and/or no damage reported. NJGS 10/26/1845 3.8 Greater NYC Area* N/A N/A No reference and/or no damage reported. Lamont-Doherty 9/9/1848 4.4 Greater NYC area* N/A N/A No reference and/or no damage reported. Lamont-Doherty 3/5/1861 0.0 Newark, NJ N/A N/A No reference and/or no damage reported. NJGS Near Nyack and 12/11/1874 3.4 N/A N/A No reference and/or no damage reported. Lamont-Doherty Tarrytown, NY 9/10/1877 0.0 Burlington, NJ N/A N/A No reference and/or no damage reported. NJGS 8/10/1880 0.0 Near Morristown, NJ N/A N/A 1 aftershock 9/1/1880. NJGS Threw down chimneys; felt from Virginia to 8/10/1884 5.2 Greater NYC Area N/A N/A Lamont-Doherty Maine 1/4/1885 3.4 Hudson Valley N/A N/A No reference and/or no damage reported. Lamont-Doherty NJGS, Lamont- 9/1/1895 4.1 Near High Bridge, NJ N/A N/A Location determined by fire and aftershock Doherty 5/27/1902 0.0 Bayonne-Wayne, NJ N/A N/A No reference and/or no damage reported. NJGS 8/11/1902 0.0 Bayonne-Wayne, NJ N/A N/A No reference and/or no damage reported. NJGS 1/20/1905 4.5 Greater NYC Area* N/A N/A Probably located offshore Lamont-Doherty 4/23/1910 0.0 Near Atlantic City, NJ N/A N/A No reference and/or no damage reported. NJGS 11/6/1912 0.0 Near Long Beach, NJ N/A N/A No reference and/or no damage reported. NJGS 8/5/1919 0.0 Cinnaminson, NJ N/A N/A No reference and/or no damage reported. NJGS NJGS, Lamont- 6/1/1927 3.9 Near Asbury Park, NJ N/A N/A High intensity in Asbury Park. Doherty 1/25/1933 0.0 Near Trenton, NJ N/A N/A No reference and/or no damage reported. NJGS Western Long Island, 7/19/1937 3.5 N/A N/A One or few earthquakes beneath Long Island Lamont-Doherty NY 9/30/1937 0.0 Verona, NJ N/A N/A No reference and/or no damage reported. NJGS 5/16/1938 0.0 Verona, NJ N/A N/A No reference and/or no damage reported. NJGS NJGS, Lamont- 8/23/1938 3.8 NE of New Egypt, NJ N/A N/A No reference and/or no damage reported. Doherty 8/23/1938 4.0 Freehold, NJ N/A N/A 4 aftershocks felt. NJGS

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FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 12/6/1938 0.0 Verona, NJ N/A N/A No reference and/or no damage reported. NJGS 9/13/1939 0.0 Union City, NJ N/A N/A No reference and/or no damage reported. NJGS 11/15/1939 3.4 Salem County, NJ N/A N/A No reference and/or no damage reported. NJGS 4/1/1947 2.7 Pompton Lakes NJ N/A N/A No reference and/or no damage reported. NJGS 10/16/1949 0.0 Hopewell, NJ N/A N/A No reference and/or no damage reported. NJGS 9/3/1951 3.6 Rockland County, NY N/A N/A No reference and/or no damage reported. Lamont-Doherty 8/17/1953 3.2 Bergen County, NJ N/A N/A No reference and/or no damage reported. NJGS 3/31/1954 0.0 Long Branch, NJ N/A N/A No reference and/or no damage reported. NJGS Schooley's Mountain, NJGS, Lamont- 3/23/1957 2.9 N/A N/A Walls cracked, dishes broke. NJ Doherty 5 km W of 12/27/1961 2.7 N/A N/A No reference and/or no damage reported. NJGS Flemington, NJ 10/13/1962 0.0 Pompton Lakes, NJ N/A N/A 1 aftershock 12/20/1962. NJGS 12/10/1968 2.7 SE of Camden, NJ N/A N/A No reference and/or no damage reported. NJGS 4/25/1969 0.0 Near Sussex, NJ N/A N/A No reference and/or no damage reported. NJGS 10/6/1969 0.0 Ogdensburg, NJ N/A N/A No reference and/or no damage reported. NJGS 2/28/1973 3.5 E.OF Wilmington, DE N/A N/A No reference and/or no damage reported. NJGS 7/10/1973 2.6 E.OF Wilmington, DE N/A N/A No reference and/or no damage reported. NJGS 3/11/1976 2.8 Pompton Lakes, NJ N/A N/A 1 aftershock, some damage. NJGS 4/13/1976 3.1 Near Ridgefield, NJ N/A N/A The shock felt widely. NJGS 12/5/1976 0.0 N/A N/A No reference and/or no damage reported. NJGS Schooley's Mountain, 12/5/1976 1.8 N/A N/A 1 aftershock 12/07/1976. NJGS NJ 1/21/1977 2.7 Lakehurst, NJ N/A N/A No reference and/or no damage reported. NJGS 6/10/1977 1.1 High Bridge, NJ N/A N/A No reference and/or no damage reported. NJGS 7/2/1977 2.3 Hampton, NJ N/A N/A No reference and/or no damage reported. NJGS 10/27/1977 1.5 Sparta, NJ N/A N/A No reference and/or no damage reported. NJGS 11/27/1977 1.8 Oakland, NJ N/A N/A No reference and/or no damage reported. NJGS Schooley's Mountain, 5 foreshocks 12/4 to12/8 and 5 aftershocks 12/23/1977 2.3 N/A N/A NJGS NJ 12/23 2/15/1978 1.6 Boonton, NJ N/A N/A No reference and/or no damage reported. NJGS 4/3/1978 2.0 Off Sandy Hook N/A N/A No reference and/or no damage reported. NJGS 5/18/1978 1.5 Bloomingdale, NJ N/A N/A No reference and/or no damage reported. NJGS 6/16/1978 0.0 Sparta, NJ N/A N/A No reference and/or no damage reported. NJGS 6/30/1978 2.9 Mahwah-Oakland, NJ N/A N/A 1 aftershock on same day. NJGS 1/30/1979 3.5 Cheesequake, NJ N/A N/A No reference and/or no damage reported. NJGS

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FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 2/2/1979 1.9 Chester, NJ N/A N/A No reference and/or no damage reported. NJGS 2/23/1979 2.9 Chester, NJ N/A N/A No reference and/or no damage reported. NJGS 3.1 Bernardsville, NJ NJGS, Lamont- 3/10/1979 “Cheesequake (epicenter in Morris N/A N/A Felt by some people in Manhattan Doherty Earthquake” County) 3/25/1980 2.8 Hainesburg, NJ N/A N/A No reference and/or no damage reported. NJGS 4/5/1980 2.9 S. of Seaside, NJ N/A N/A No reference and/or no damage reported. NJGS 8/2/1980 2.8 Keyport, NJ N/A N/A No reference and/or no damage reported. NJGS 8/30/1980 3.0 Medford Lakes, NJ N/A N/A No reference and/or no damage reported. NJGS 3/19/1981 2.0 Boonton, NJ N/A N/A No reference and/or no damage reported. NJGS 5/18/1981 2.1 Ramsey, NJ N/A N/A No reference and/or no damage reported. NJGS 6/21/1981 1.8 Denville, NJ N/A N/A No reference and/or no damage reported. NJGS 4/12/1982 2.4 Mt Holly, NJ N/A N/A No reference and/or no damage reported. NJGS 7/29/1982 2.4 Seaside Heights, NJ N/A N/A No reference and/or no damage reported. NJGS 9/16/1982 1.6 Franklin, NJ N/A N/A No reference and/or no damage reported. NJGS 2/19/1983 2.7 Oldwick, NJ N/A N/A No reference and/or no damage reported. NJGS 6/1/1983 1.5 Dover, NJ N/A N/A No reference and/or no damage reported. NJGS 9/6/1983 1.5 Fort Lee, NJ N/A N/A No reference and/or no damage reported. NJGS 9/15/1983 1.5 Ringwood, NJ N/A N/A No reference and/or no damage reported. NJGS 3/12/1984 2.0 Asbury Park, NJ N/A N/A No reference and/or no damage reported. NJGS 5/13/1984 2.1 Mount Hope, NJ N/A N/A No reference and/or no damage reported. NJGS 6/3/1984 1.3 Kinnelon, NJ N/A N/A No reference and/or no damage reported. NJGS 6/6/1984 1.7 Near Morristown, NJ N/A N/A No reference and/or no damage reported. NJGS 8/2/1984 1.7 Mount Olive, NJ N/A N/A No reference and/or no damage reported. NJGS 8/12/1984 2.4 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS 8/12/1984 2.1 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS 10/25/1984 2.0 Near Mt. Olive, NJ N/A N/A No reference and/or no damage reported. NJGS 12/3/1984 1.5 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS 12/13/1984 1.7 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS 12/14/1984 1.7 N of Milford, NJ N/A N/A No reference and/or no damage reported. NJGS 12/15/1984 1.8 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS 12/17/1984 1.6 Byram, NJ N/A N/A No reference and/or no damage reported. NJGS Many people in the NYC area felt this 10/19/1985 4 Ardsley, NY N/A N/A Lamont-Doherty earthquake 2/8/1986 1.7 Flanders, NJ N/A N/A No reference and/or no damage reported. NJGS 2/23/1986 1.8 Port Murray, NJ N/A N/A No reference and/or no damage reported. NJGS

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-18 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 6/29/1986 1.5 Kinnelon, NJ N/A N/A No reference and/or no damage reported. NJGS 7/15/1986 1.5 Franklin, NJ N/A N/A No reference and/or no damage reported. NJGS 9/15/1986 2.3 Near New Egypt, NJ N/A N/A No reference and/or no damage reported. NJGS 9/15/1986 1.9 Near Roebling, NJ N/A N/A No reference and/or no damage reported. NJGS 11/23/1986 2.8 Tranquility, NJ N/A N/A Felt in Sussex and Warren. NJGS South of Lake 4/24/1987 1.9 N/A N/A No reference and/or no damage reported. NJGS Mohawk, NJ 5/16/1987 1.4 Near Paterson, NJ N/A N/A No reference and/or no damage reported. NJGS 8/5/1987 1.7 SW of Newton N/A N/A No reference and/or no damage reported. NJGS 8/6/1987 1.1 SW of Newton N/A N/A No reference and/or no damage reported. NJGS 8/6/1987 1.1 SW of Newton, NJ N/A N/A No reference and/or no damage reported. NJGS 12/6/1987 2.1 Burlington, NJ N/A N/A No reference and/or no damage reported. NJGS 4/13/1988 1.4 Dover, NJ N/A N/A No reference and/or no damage reported. NJGS 10 KM NW of 8/20/1988 1.0 N/A N/A No reference and/or no damage reported. NJGS Morristown, NJ 12/22/1988 1.0 Wanaque, NJ N/A N/A No reference and/or no damage reported. NJGS 12/23/1988 1.1 Wanaque, NJ N/A N/A No reference and/or no damage reported. NJGS 1/22/1989 2.0 Englewood, NJ N/A N/A No reference and/or no damage reported. NJGS 1/27/1989 1.1 NY-NJ Border N/A N/A No reference and/or no damage reported. NJGS 9/3/1989 2.0 S of Staten Island N/A N/A No reference and/or no damage reported. NJGS 9/3/1989 2.5 S of Staten Island N/A N/A No reference and/or no damage reported. NJGS 1/26/1990 1.0 Franklin, NJ N/A N/A No reference and/or no damage reported. NJGS 5/10/1990 1.8 Mt. Freedom, NJ N/A N/A No reference and/or no damage reported. NJGS 8/21/1990 0.7 Wanaque, NJ N/A N/A No reference and/or no damage reported. NJGS 10/23/1990 2.9 Hancock's Bridge, NJ N/A N/A Felt in NJ, DE and PA. NJGS 5/12/1991 1.3 Wanaque, NJ N/A N/A No reference and/or no damage reported. NJGS 7/5/1991 1.3 Pompton Plains, NJ N/A N/A No reference and/or no damage reported. NJGS 9/29/1991 2.2 Somerdale Boro, NJ N/A N/A No reference and/or no damage reported. NJGS 1/9/1992 3.1 New Brunswick, NJ N/A N/A No reference and/or no damage reported. NJGS 3/4/1992 1.4 Kinnelon, NJ N/A N/A No reference and/or no damage reported. NJGS Jefferson Township, 6/7/1992 0.4 N/A N/A No reference and/or no damage reported. NJGS NJ 10/13/1992 1.0 West Milford, NJ N/A N/A No reference and/or no damage reported. NJGS 2/26/1993 2.5 Cherry Hill, NJ N/A N/A No reference and/or no damage reported. NJGS 5/15/1993 2.6 Perrineville, NJ N/A N/A No reference and/or no damage reported. NJGS 5/23/1994 1.6 Butler, N.J. N/A N/A No reference and/or no damage reported. NJGS

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-19 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 1/27/1995 2.3 Rockaway, NJ N/A N/A No reference and/or no damage reported. NJGS 4/1/1995 1.5 Rockaway, NJ N/A N/A No reference and/or no damage reported. NJGS 5/26/1995 1.5 Kinnelon, NJ N/A N/A No reference and/or no damage reported. NJGS 10/27/1995 1.3 NE of Newton, NJ N/A N/A No reference and/or no damage reported. NJGS 10/27/1995 1.4 NE of Newton, NJ N/A N/A No reference and/or no damage reported. NJGS 2/18/1996 1.5 Ringwood N/A N/A No reference and/or no damage reported. NJGS 2/19/1996 1.7 Ringwood, NJ N/A N/A 1 aftershock 22 minutes later. NJGS 5 km W Ringwood, 2/19/1996 0.8 N/A N/A No reference and/or no damage reported. NJGS NJ 6.4 km W of 2/23/1996 0.8 N/A N/A No reference and/or no damage reported. NJGS Ringwood, NJ Near Mt. Arlington, 2/26/1996 0.0 N/A N/A No reference and/or no damage reported. NJGS NJ 9 km S Crestwood 10/24/1996 2.0 N/A N/A No reference and/or no damage reported. NJGS Village, NJ 21 km NE Newton, 11/12/1996 1.3 N/A N/A No reference and/or no damage reported. NJGS NJ 21 km NE Newton, 11/12/1996 0.8 N/A N/A No reference and/or no damage reported. NJGS NJ 3 km W of Rendall 3/11/1997 0.0 N/A N/A No reference and/or no damage reported. NJGS Park, NJ 5/25/1997 0.5 1 km NE Fort Lee, NJ N/A N/A No reference and/or no damage reported. NJGS 4.6 km N of 6/27/1997 1.6 N/A N/A No reference and/or no damage reported. NJGS Rockaway, NJ 12 km NE of 7/15/1997 2.3 N/A N/A No reference and/or no damage reported. NJGS Princeton, NJ 3 km SW Woodcliff 10/21/1997 0.5 N/A N/A No reference and/or no damage reported. NJGS Lake, NJ 3 km SW Secaucus, 10/24/1997 0.5 N/A N/A No reference and/or no damage reported. NJGS NJ 3/25/1998 1.9 13 km S Salem, NJ N/A N/A No reference and/or no damage reported. NJGS 6/20/1998 1.2 2 km SE Kinnelon, NJ N/A N/A No reference and/or no damage reported. NJGS 6/30/1998 1.9 3 km S Butler, NJ N/A N/A No reference and/or no damage reported. NJGS 1 km NW of Clifton, 1/12/1999 1.4 N/A N/A No reference and/or no damage reported. NJGS NJ 2 km W of Emerson, 1/31/1999 1.5 N/A N/A No reference and/or no damage reported. NJGS NJ

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-20 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number 8 km W of Fort Dix, 5/31/1999 2.3 N/A N/A No reference and/or no damage reported. NJGS NJ Felt in the Upper East Side of Manhattan, 1/17/2001 2.4 Manhattan N/A N/A Lamont-Doherty Long Island City, and Queens 7.1 km NE of 7/14/2001 1.9 N/A N/A No reference and/or no damage reported. NJGS Boonton, NJ Felt in the Upper East Side of Manhattan, 10/17/2001 2.6 Manhattan N/A N/A Lamont-Doherty Long Island City, Astoria, and Queens 5.4 km N of Somerville, NJ 8/9/2002 1.5 N/A N/A No reference and/or no damage reported. NJGS (epicenter in Bridgewater) 6 km SW of Morris 8/24/2003 1.5 N/A N/A No reference and/or no damage reported. NJGS Plains, 3 km North of Milford, 8/26/2003 3.5 N/A N/A No reference and/or no damage reported. NJGS NJ 2km NE from 3/22/2004 2.1 N/A N/A No reference and/or no damage reported. NJGS Runnemede, NJ 6km ESE from 12/17/2004 2.0 N/A N/A No reference and/or no damage reported. NJGS Pennsville, NJ 1.3 Km East of Lodi, 04/23/2005 1.9 N/A N/A No reference and/or no damage reported. NJGS NJ 16 km W of Franklin 12/09/2005 2.1 N/A N/A Aftershock 55 min later, 1.3 M NJGS Lakes, NJ 22km NE of Newton, 02/16/2006 2.6 N/A N/A No reference and/or no damage reported. NJGS NJ 20km NE of Newton, 02/17/2006 0.9 N/A N/A No reference and/or no damage reported. NJGS NJ 20.4km NE of 02/21/2006 1.3 N/A N/A No reference and/or no damage reported. NJGS Newton, NJ 9 km S of Fair Lawn, 05/15/2006 2.0 N/A N/A No reference and/or no damage reported. NJGS NJ 7 km E of Fairfield, 06/28/2007 2.1 N/A N/A No reference and/or no damage reported. NJGS NJ There were reports of people having felt this 3.5km SSW of 02/03/2009 3.0 N/A N/A earthquake throughout New Jersey, including NJGS, USGS Rockaway, NJ reports in Somerset County. 02/14/2009 2.4 5 km NNE of N/A N/A There were reports of people having felt this NJGS, USGS

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-21 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number Boonton, NJ earthquake throughout New Jersey, including reports in Somerset County. 3 km SSW of 2/18/2009 1.1 N/A N/A No reference and/or no damage reported. NJGS Kinnelon, NJ 1 km ESE of Oradell, 2/16/2009 1.4 N/A N/A No reference and/or no damage reported. NJGS NJ 2 km SSE of Dover, 2/16/2009 2.3 N/A N/A No reference and/or no damage reported. NJGS NJ There were reports of people having felt this 2.25km ESE of 07/01/2009 2.8 N/A N/A earthquake throughout New Jersey, including NJGS, USGS Pennsville, NJ reports in Somerset County. 13 km S of 12/21/2009 2.3 N/A N/A No reference and/or no damage reported. NJGS Phillipsburg, NJ 8 km NW of Morris 12/26/2009 2.0 N/A N/A No reference and/or no damage reported. NJGS Plains, NJ 3 km NW of Far Hills, 02/05/2010 1.5 N/A N/A No reference and/or no damage reported. NJGS NJ 3 km NW of far Hills, 02/07/2010 1.2 N/A N/A No reference and/or no damage reported. NJGS NJ 02/10/2010 2.2 1 km W of Wanaque N/A N/A No reference and/or no damage reported. NJGS This earthquake hit just before 9am and prompted numerous phone calls to police. No damages were reported. Many people in New Jersey reported having felt this NJGS, USGS, 02/21/2010 2.6 Gladstone, NJ N/A N/A earthquake, including reports in Somerset NJ.com County. In Bernardsville, approximately 100 people called the police stating they felt/heard the earthquake. This event was most likely an aftershock from the morning’s earthquake. Numerous people NJGS, USGS, 02/21/2010 2.3 Gladstone, NJ N/A N/A in New Jersey reported having felt this NJ.com earthquake, including reports in Somerset County. 6 km SE of People reported having felt this earthquake, 06/06/2010 2.3 N/A N/A NJGS, USGS Sayreville, NJ including reports in Somerset County. 12/25/2010 2.1 1 km W of Clifton, NJ N/A N/A No reference and/or no damage reported. NJGS 1 km SW of Clifton, 05/08/2011 1.2 N/A N/A No reference and/or no damage reported. NJGS NJ 05/10/2011 1.9 2 km N of Mt. Holly, N/A N/A No reference and/or no damage reported. NJGS

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-22 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

FEMA Date(s) of County Magnitude Location Declaration Losses/Impacts Source(s) Event Designated? Number NJ 3 km S of Fort Lee, 05/29/2011 1.3 N/A N/A No reference and/or no damage reported. NJGS NJ 24 km SSW of 05/29/2011 1.9 N/A N/A No reference and/or no damage reported. NJGS Lakehurst, NJ 2 km SE of S. 06/09/2011 1.6 N/A N/A No reference and/or no damage reported. NJGS Plainfield, NJ 16 km NW of 07/17/2012 1.1 N/A N/A No reference and/or no damage reported. NJGS Morristown, NJ 18 km NW of 07/18/2012 1.1 N/A N/A No reference and/or no damage reported. NJGS Morristown, NJ 1.4 km E of 08/23/2012 1.2 N/A N/A No reference and/or no damage reported. NJGS Ringwood, NJ People reported having felt this earthquake in 3 km SW of Mahwah, 11/05/2012 2.0 N/A N/A various parts of New Jersey, including reports NJGS, USGS NJ in Somerset County. Greater Philadelphia Numerous reports of people having felt the 11/23/2012 2.2 N/A N/A NJGS, USGS Area/New Jersey earthquake in southwestern New Jersey. Source: NJGS, 2013; USGS, 2013; Won-Young Kim, Lamont-Doherty Earth Observatory of Columbia University, 1999 Note: Yellow shading indicates an event that occurred in Somerset County. * Location very poorly determined; may be uncertain by 50 miles. E East NYC New York City FEMA Federal Emergency Management Agency NYSDPC New York State Disaster Preparedness Commission Km Kilometers S South N North USGS U.S. Geological Survey N/A Not Applicable W West NJ New Jersey NJGS New Jersey Geologicaly Survey

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-23 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

Earthquakes in Somerset County are not common, with documented information on earthquake events and their location being relatively scarce. According to Planning Area officials, there is no record of earthquake occurrences within the Planning Area. However, depending on the magnitude, the impacts of earthquake events can be far-reaching; therefore, reported incidences within the surrounding counties or states could have created indirect impacts upon the Planning Area.

Probability of Future Events

Earthquake hazard maps illustrate the distribution of earthquake shaking levels that have a certain probability of occurring over a given time period. According to the USGS, in 2008, Somerset County had a PGA of 3-4%g for earthquakes with a 10-percent probability of occurring within 50 years.

Earlier in this section, the identified hazards of concern for Somerset County were ranked. The probability of occurrence, or likelihood of the event, is one parameter used for ranking hazards. Based on historical records and input from the Planning Committee, the probability of occurrence for earthquakes in the County is considered “frequent” (is likely to occur within 25 years as presented in Table 5.3-3). Although no reported incidences have occurred within Somerset County, it is anticipated that the County will experience indirect impacts from earthquakes that may affect the general building stock, local economy and may induce secondary hazards such ignite fires and cause utility failure.

Climate Change

The impacts of global climate change on earthquake probability are unknown. Some scientists say that melting glaciers could induce tectonic activity. As ice melts and water runs off, tremendous amounts of weight are shifted on the earth’s crust. As newly freed crust returns to its original, pre-glacier shape, it could cause seismic plates to slip and stimulate volcanic activity according to research into prehistoric earthquakes and volcanic activity. NASA and USGS scientists found that retreating glaciers in southern Alaska may be opening the way for future earthquakes (NASA, 2004).

Secondary impacts of earthquakes could be magnified by climate change. Soils saturated by repetitive storms could experience liquefaction during seismic activity due to the increased saturation. Dams storing increased volumes of water due to changes in the hydrograph could fail during seismic events. There are currently no models available to estimate these impacts

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-24 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

VULNERABILITY ASSESSMENT

To understand risk, a community must evaluate what assets are exposed or vulnerable in the identified hazard area. For the earthquake hazard, the entire County has been identified as the exposed hazard area. Therefore, all assets in Somerset County (population, structures, critical facilities and lifelines), as described in the County Profile (Section 4), are vulnerable. The following section includes an evaluation and estimation of the potential impact of the earthquake hazard on Somerset County including the following:  Overview of vulnerability  Data and methodology used for the evaluation  Impact on: (1) life, safety and health of residents, (2) general building stock, (3) critical facilities, (4) economy and (5) future growth and development  Effect of climate change on vulnerability  Change of vulnerability as compared to that presented in the 2008 Somerset County Hazard Mitigation Plan  Further data collections that will assist understanding of this hazard over time

Overview of Vulnerability

Earthquakes usually occur without warning and can impact areas a great distance from their point of origin. The extent of damage depends on the density of population and building and infrastructure construction in the area shaken by the quake. Some areas may be more vulnerable than others based on soil type, the age of the buildings and building codes in place. Compounding the potential for damage – historically, Building Officials Code Administration (BOCA) used in the Northeast were developed to address local concerns including heavy snow loads and wind; seismic requirements for design criteria are not as stringent compared to the west coast’s reliance on the more seismically-focused Uniform Building Code). As such, a smaller earthquake in the Northeast can cause more structural damage than if it occurred out west.

The level of seismic hazard, the frequency and severity of earthquakes, is substantially lower in New Jersey than in more seismically active states such as California or Alaska. The level of seismic risk, the threat to buildings, infrastructure, and people, is significant in the State, especially in northern New Jersey. The level of seismic risk (potential damages) in the State is higher than might be expected because the vast majority of the buildings and infrastructure in New Jersey have been built with minimal or no consideration of earthquakes; therefore, the majority of buildings and infrastructure in the State is more vulnerable to earthquake damage than the buildings and infrastructure in more seismically active states where inventory has been built with consideration of earthquakes (NJOEM, 2011). The entire population and general building stock inventory of the County is at risk of being damaged or experiencing losses due to impacts of an earthquake. Potential losses associated with the earth shaking were calculated for Somerset County for three probabilistic earthquake events, the 100-year, 500- and 2,500-year mean return periods (MRP). The impacts on population, existing structures, critical facilities and the economy within Somerset County are presented below, following a summary of the data and methodology used.

Data and Methodology

A probabilistic assessment was conducted for Somerset County for the 100-, 500- and 2,500-year MRPs through a Level 2 analysis in HAZUS-MH 2.1 to analyze the earthquake hazard and provide a range of loss estimates for Somerset County. The probabilistic method uses information from historic earthquakes

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-25 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE and inferred faults, locations and magnitudes, and computes the probable ground shaking levels that may be experienced during a recurrence period by Census tract. According to the New York City Area Consortium for Earthquake Loss Mitigation (NYCEM), probabilistic estimates are best for urban planning, land use, zoning and seismic building code regulations (NYCEM, 2003). The default assumption is a magnitude 7 earthquake for all return periods. In addition, an annualized loss run was also conducted in HAZUS-MH 2.1 to estimate the annualized general building stock dollar losses for Somerset County.

Ground shaking is the primary cause of earthquake damage to man-made structures and soft soils amplify ground shaking. One contributor to the site amplification is the velocity at which the rock or soil transmits shear waves (S-waves). The NEHRP developed five soil classifications defined by their shear- wave velocity that impact the severity of an earthquake. The soil classification system ranges from A to E, where A represents hard rock that reduces ground motions from an earthquake and E represents soft soils that amplify and magnify ground shaking and increase building damage and losses.

As illustrated in Figure 5.4.7-3 as depicted by the New Jersey Geologic and Water Survey, Somerset County is made up of dense soil/soft rock (C), stiff/soft soils (D) with a small area of soft soils (E) in the northeastern portion of the county. When unchanged, HAZUS-MH default soil types are class “D”. To more closely reflect the soils of the County as indicated by the New Jersey Geological and Water Survey (not available in time for this analysis), HAZUS-MH was updated with the approximate locations of NEHRP soil classes C and D, as illustrated in Figure 5.4.7-12 below, with the class ‘D’ soils closely following riverine reaches and floodplains.

In addition to the probabilistic scenarios mentioned, an annualized loss run was conducted in HAZUS 2.1 to estimate the annualized general building stock dollar losses for the County. The annualized loss methodology combines the estimated losses associated with ground shaking for eight return periods: 100, 250, 500, 750, 1000, 1500, 2000, 2500-year, which are based on values from the USGS seismic probabilistic curves. Annualized losses are useful for mitigation planning because they provide a baseline upon which to 1) compare the risk of one hazard across multiple jurisdictions and 2) compare the degree of risk of all hazards for each participating jurisdiction.

As noted in the HAZUS-MH Earthquake User Manual ‘Uncertainties are inherent in any loss estimation methodology. They arise in part from incomplete scientific knowledge concerning earthquakes and their effects upon buildings and facilities. They also result from the approximations and simplifications that are necessary for comprehensive analyses. Incomplete or inaccurate inventories of the built environment, demographics and economic parameters add to the uncertainty. These factors can result in a range of uncertainly in loss estimates produced by the HAZUS Earthquake Model, possibly at best a factor of two or more.’ However, HAZUS’ potential loss estimates are acceptable for the purposes of this HMP.

The occupancy classes available in HAZUS-MH 2.1 were condensed into the following categories (residential, commercial, industrial, agricultural, religious, government, and educational) to facilitate the analysis and the presentation of results. Residential loss estimates address both multi-family and single family dwellings. Impacts to critical facilities and utilities were also evaluated.

Data used to assess this hazard include data available in the HAZUS-MH 2.1 earthquake model, USGS data, data provided by NJOEM, professional knowledge, and information provided by the County’s Planning Committee. All exposure and loss estimates discussed in the assessment below are for Somerset County.

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-26 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE

Figure 5.4.7-12. Estimated NEHRP Soil Classes in Somerset County Used for the Earthquake Analysis

Source: FEMA, 2009 Note: To estimate the location of the NEHRP soils, FEMA floodplains were classified as soil type D with the remainder of the County soil type C for the purposes of this risk assessment.

Impact on Life, Health and Safety

Overall, the entire population of Somerset County is exposed to the earthquake hazard event. According to the 2010 U.S. Census, Somerset County had a population of 323,444 people. The impact of earthquakes on life, health and safety is dependent upon the severity of the event. Risk to public safety and loss of life from an earthquake in Somerset County is minimal with higher risk occurring in buildings as a result of damage to the structure, or people walking below building ornamentation and chimneys that may be shaken loose and fall as a result of the quake.

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Populations considered most vulnerable are located in the built environment, particularly near unreinforced masonry construction. In addition, the vulnerable population includes the elderly (persons over the age of 65) and individuals living below the Census poverty threshold. These socially vulnerable populations are most susceptible, based on a number of factors including their physical and financial ability to react or respond during a hazard and the location and construction quality of their housing. Table 5.4.7-7 summarizes the County population over the age of 65 and individuals living below the Census poverty threshold.

Table 5.4.7-7. Somerset County Population Statistics (2010 U.S. Census) U.S. Census 2010 U.S. Census 2010 Census Low- U.S. Census 2010 Population Population Income Population Over 65 Under 5 Households * 323,444 40,002 19,237 10,113 Source: U.S. Census, 2010 Note: *2007-2011 American Community Survey (5-Year Estimates) - Households with an income of less than $24,999

Residents may be displaced or require temporary to long-term sheltering due to the event. The number of people requiring shelter is generally less than the number displaced as some displaced persons use hotels or stay with family or friends following a disaster event. Table 5.4.7-8 summarizes the households HAZUS-MH 2.1 estimates will be displaced and population that may require short-term sheltering as a result of the 100-, 500- and 2,500-year MRP earthquake events.

Table 5.4.7-8. Summary of Estimated Sheltering Needs for Somerset County

Displaced Persons Seeking Scenario Households Short-Term Shelter 100-Year Earthquake 0 0 500-Year Earthquake 12 7 2,500-Year Earthquake 269 159 Source: HAZUS-MH 2.1

Table 5.4.7-9. Estimated Displaced Households and Population Seeking Short-Term Shelter from the 500- and 2,500-year MRP Events per Municipality

500-Year MRP Event 2,500-Year MRP Event Persons Persons Seeking Displaced Seeking Short- Displaced Short-Term Municipality Households Term Sheltering Households Sheltering Bedminister (T) 0 0 3 1 Bernards (T) 1 0 13 5 Bernardsville (B) 0 0 5 2 Bound Brook (B) 1 1 19 14 Branchburg (T) 0 0 6 3 Bridgewater (T) 1 1 28 15 Far Hills (B) 0 0 1 0 Franklin (T) 2 1 49 27 Green Brook (T) 0 0 3 2 Hillsborough (T) 1 1 24 12

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500-Year MRP Event 2,500-Year MRP Event Persons Persons Seeking Displaced Seeking Short- Displaced Short-Term Municipality Households Term Sheltering Households Sheltering Manville (B) 1 0 19 10 Millstone (B) 0 0 0 0 Montgomery (T) 0 0 7 4 North Plainfield (B) 2 2 46 34 Peapack Gladstone (B) 0 0 1 1 Raritan (B) 0 0 7 4 Rocky Hill (B) 0 0 0 0 Somerville (B) 1 1 23 15 South Bound Brook (B) 0 0 7 5 Warren (T) 0 0 2 1 Watchung (B) 0 0 5 2 Somerset County (Total) 12 7 269 159 Source: HAZUS-MH 2.1 Note: The population displaced and seeking shelter was calculated using the 2000 U.S. Census data (HAZUS-MH 2.1 default demographic data).

According to the 1999-2003 NYCEM Summary Report (Earthquake Risks and Mitigation in the New York / New Jersey / Connecticut Region), there is a strong correlation between structural building damage and the number of injuries and casualties from an earthquake event. Further, the time of day also exposes different sectors of the community to the hazard. For example, HAZUS considers the residential occupancy at its maximum at 2:00 a.m., where the educational, commercial and industrial sectors are at their maximum at 2:00 p.m., and peak commute time is at 5:00 p.m. Whether directly impacted or indirectly impact, the entire population will have to deal with the consequences of earthquakes to some degree. Business interruption could keep people from working, road closures could isolate populations, and loss of functions of utilities could impact populations that suffered no direct damage from an event itself.

There are no injuries or casualties estimated for the 100-year event. An estimated 6 to 7 injuries that require medical attention (no hospitalization), and one injury which requires hospitalization are estimated for the 500-year event. There are zero casualties estimated for the 500-year event.

Table 5.4.7-10 summarizes the injuries and casualties estimated for the 2,500-year MRP earthquake event.

Table 5.4.7-10. Estimated Number of Injuries and Casualties from the 2,500-Year MRP Earthquake Event

Time of Day Level of Severity 2:00 AM 2:00 PM 5:00 PM Injuries 95 114 99 Hospitalization 13 19 18 Casualties 2 3 3 Source: HAZUS-MH 2.1

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Impact on General Building Stock

After considering the population exposed to the earthquake hazard, the value of general building stock exposed to and damaged by 100-, 500- and 2,500-year MRP earthquake events was evaluated. In addition, annualized losses were calculated using HAZUS-MH 2.1. The entire study area’s general building stock is considered at risk and exposed to this hazard.

As stated earlier, soft soils (NEHRP soil classed D and E) can amplify ground shaking to damaging levels even in a moderate earthquake (NYCEM, 2003). Therefore, buildings located on NEHRP soil classes D and E have an increased risk of damages from an earthquake. Table 5.4.7-11 summarizes the number of buildings in Somerset County on the approximately located NEHRP soils classed D.

Table 5.4.7-11. Buildings Located on NEHRP Soils Classed D in Somerset County

Number of Total Buildings on Percent Buildings Building NEHRP Soil on NEHRP Soil Municipality Count Class D Class D Bedminister (T) 2,531 86 3.4 Bernards (T) 7,576 101 1.3 Bernardsville (B) 3,282 71 2.2 Bound Brook (B) 3,011 874 29.0 Branchburg (T) 5,369 123 2.3 Bridgewater (T) 14,316 380 2.7 Far Hills (B) 536 40 7.5 Franklin (T) 15,592 184 1.2 Green Brook (T) 2,465 162 6.6 Hillsborough (T) 10,812 170 1.6 Manville (B) 4,250 909 21.4 Millstone (B) 221 32 14.5 Montgomery (T) 6,899 129 1.9 North Plainfield (B) 5,781 801 13.9 Peapack Gladstone (B) 1,118 77 6.9 Raritan (B) 2,418 36 1.5 Rocky Hill (B) 352 9 2.6 Somerville (B) 3,799 98 2.6 South Bound Brook (B) 1,420 85 6.0 Warren (T) 5,999 113 1.9 Watchung (B) 2,206 58 2.6 Somerset County (Total) 99,953 4,538 4.5

The HAZUS-MH 2.1 model estimates the value of the exposed building stock and the loss (in terms of damage to the exposed stock). Refer to Table 4-3 in the County Profile (Section 4) for general building stock data replacement value statistics (structure and contents).

For this plan update and using HAZUS-MH 2.1, a probabilistic model was run for the purposes of this Plan to estimate annualized dollar losses for Somerset County, also factoring in approximate location of NEHRP soil classes C and D. Annualized losses are useful for mitigation planning because they provide a baseline upon which to 1) compare the risk of one hazard across multiple jurisdictions and 2) compare the degree of risk of all hazards for each participating jurisdiction. Please note that annualized loss does

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-30 August 2013 SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE not predict what losses will occur in any particular year. The estimated annualized losses are approximately $949,314 per year (building and contents) for the County.

According to NYCEM, where earthquake risks and mitigation were evaluated in the New York, New Jersey and Connecticut region, most damage and loss caused by an earthquake is directly or indirectly the result of ground shaking (NYCEM, 2003). NYCEM indicates there is a strong correlation between PGA and the damage a building might experience. The HAZUS-MH model is based on the best available earthquake science and aligns with these statements. HAZUS-MH 2.1 methodology and model were used to analyze the earthquake hazard for the general building stock for Somerset County. See Figure 5.4.7-4 through 5.4.7-6 earlier in this profile that illustrates the geographic distribution of PGA (g) across the County for 100-, 500- and 2,500-year MRP events at the Census-Tract level.

In addition, according to NYCEM, a building’s construction determines how well it can withstand the force of an earthquake. The NYCEM report indicates that un-reinforced masonry buildings are most at risk during an earthquake because the walls are prone to collapse outward, whereas steel and wood buildings absorb more of the earthquake’s energy. Additional attributes that contribute to a building’s capability to withstand an earthquake’s force include its age, number of stories and quality of construction. HAZUS-MH considers building construction and the age of buildings as part of the analysis. Because the default general building stock was used for this HAZUS-MH analysis, the default building ages and building types already incorporated into the inventory were used.

Potential building damage was evaluated by HAZUS-MH 2.1 across the following damage categories (none, slight, moderate, extensive and complete). Table 5.4.7-12 provides definitions of these five categories of damage for a light wood-framed building; definitions for other building types are included in HAZUS-MH technical manual documentation. General building stock damage for these damage categories by occupancy class and building type on a County-wide basis is summarized for the 100-, 500- and 2,500-year events in 3, 4, and 5.

Table 5.4.7-12. Example of Structural Damage State Definitions for a Light Wood-Framed Building

Damage Category Description Small plaster or gypsum-board cracks at corners of door and window openings and wall-ceiling Slight intersections; small cracks in masonry chimneys and masonry veneer. Large plaster or gypsum-board cracks at corners of door and window openings; small diagonal Moderate cracks across shear wall panels exhibited by small cracks in stucco and gypsum wall panels; large cracks in brick chimneys; toppling of tall masonry chimneys. Large diagonal cracks across shear wall panels or large cracks at plywood joints; permanent lateral movement of floors and roof; toppling of most brick chimneys; cracks in foundations; Extensive splitting of wood sill plates and/or slippage of structure over foundations; partial collapse of room- over-garage or other soft-story configurations. Structure may have large permanent lateral displacement, may collapse, or be in imminent danger Complete of collapse due to cripple wall failure or the failure of the lateral load resisting system; some structures may slip and fall off the foundations; large foundation cracks. Source: HAZUS-MH Technical Manual

HAZUS-MH 2.1 estimates $0 in damage to Somerset County’s general building stock as a result of a 100-year MRP event. Table 5.4.7-13 through Table 5.4.7-15 summarizes the damage estimated for the 100-, 500- and 2,500-year MRP earthquake events. Damage loss estimates include structural and non- structural damage to the building and loss of contents.

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Table 5.4.7-13. Estimated Buildings Damaged by General Occupancy for 100-year, 500-year and 2,500-year MRP Earthquake Events

Average Damage State Category 100-Year MRP 500-Year MRP 2,500-Year MRP None Slight Moderate Extensive Complete None Slight Moderate Extensive Complete None Slight Moderate Extensive Complete

Residential 88,548 0 0 0 0 86,916 1,389 224 17 1 72,337 12,375 3,383 408 46

Commercial 5,204 0 0 0 0 5,059 111 31 3 0 3,911 766 438 80 9

Industrial 850 0 0 0 0 827 17 5 0 0 637 121 77 14 1

Education, Government, 5,282 0 0 0 0 5,134 113 30 2 0 3,950 831 416 79 7 Religious and Agricultural Source: HAZUS-MH 2.1 Note: Based on an inventory of 99,884 buildings.

Table 5.4.7-14. Estimated Number of Buildings Damaged by Building Type for 100-year, 500-year and 2,500-year MRP Earthquake Events

Average Damage State Category 100-Year MRP 500-Year MRP 2,500-Year MRP None Slight Moderate Extensive Complete None Slight Moderate Extensive Complete None Slight Moderate Extensive Complete

Wood 82,933 0 0 0 0 81,688 1,124 118 3 0 68,683 11,423 2,619 196 12

Steel 5,406 0 0 0 0 5,271 104 29 2 0 4,090 735 484 88 8

Concrete 819 0 0 0 0 798 15 5 0 0 571 84 88 16 1

Reinforced Masonry 803 0 0 0 0 782 14 6 1 0 631 81 73 18 0

Un-reinforced Masonry 9,920 0 0 0 0 9,393 375 133 17 2 6,827 1,739 1,048 263 43

Manufactured housing 4 0 0 0 0 4 0 0 0 0 3 1 1 0 0 Source: HAZUS-MH 2.1 Note: Based on an inventory of 99,884 buildings.

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Table 5.4.7-15. Estimated Building Value (Building and Contents) Damaged by the 500- and 2,500-Year MRP Earthquake Events Percent of Total Building Estimated Residential Estimated Commercial Estimated Total Damages* and Contents Damage Damage Municipality RV** Annualized 500- 2,500- 500-Year 2,500-Year 500-Year 2,500-Year 500-Year 2,500-Year Loss Year Year Bedminister (T) $56,989 $3,290,664 $54,765,262 0.1 2.0 $1,482,952 $24,568,713 $656,582 $10,466,411 Bernards (T) $97,546 $5,490,480 $102,639,178 0.1 1.5 $3,830,875 $72,151,946 $930,711 $16,021,885 Bernardsville (B) $24,303 $1,259,453 $26,838,365 0.1 1.1 $897,057 $19,248,439 $138,186 $2,779,314 Bound Brook (B) $16,890 $859,307 $18,624,265 0.1 1.2 $540,619 $12,014,404 $198,429 $4,078,078 Branchburg (T) $95,778 $5,473,097 $94,138,385 0.1 1.7 $2,363,848 $42,757,801 $511,651 $8,370,261 Bridgewater (T) $118,657 $5,893,499 $129,690,154 0.1 1.1 $3,471,039 $76,779,511 $1,048,726 $21,929,530 Far Hills (B) $5,296 $260,580 $5,626,142 0.1 1.1 $118,958 $2,551,132 $35,403 $712,525 Franklin (T) $160,962 $7,780,883 $175,600,928 0.1 1.1 $4,102,040 $92,521,193 $1,340,749 $28,566,376 Green Brook (T) $19,270 $991,528 $21,487,887 0.1 1.2 $664,825 $14,715,367 $235,833 $4,848,679

Hillsborough (T) $97,035 $4,748,059 $105,490,681 0.0 1.1 $2,688,104 $59,981,007 $472,545 $9,991,329

Manville (B) $21,100 $1,169,238 $22,055,365 0.1 1.4 $758,057 $14,410,826 $258,181 $4,763,235

Millstone (B) $882 $45,153 $1,010,449 0.0 1.0 $39,305 $882,759 $2,711 $57,329

Montgomery (T) $62,660 $3,133,328 $69,227,690 0.0 1.0 $2,208,202 $49,178,491 $428,667 $9,116,240

North Plainfield $35,431 $1,868,156 $38,702,152 0.1 1.4 $1,328,197 $28,066,479 $364,440 $7,362,161 (B)

Peapack $8,968 $451,572 $9,679,269 0.1 1.1 $259,552 $5,566,242 $75,000 $1,509,453 Gladstone (B)

Raritan (B) $18,189 $861,938 $19,468,703 0.0 1.1 $353,965 $7,895,997 $184,949 $3,921,117

Rocky Hill (B) $2,137 $105,127 $2,354,074 0.0 1.0 $67,801 $1,521,058 $18,672 $397,013

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Percent of Total Building Estimated Residential Estimated Commercial Estimated Total Damages* and Contents Damage Damage Municipality RV** Annualized 500- 2,500- 500-Year 2,500-Year 500-Year 2,500-Year 500-Year 2,500-Year Loss Year Year

Somerville (B) $24,608 $1,218,753 $26,585,300 0.1 1.1 $640,387 $14,269,401 $377,667 $7,959,393

South Bound $5,575 $284,593 $6,196,581 0.1 1.2 $199,973 $4,443,605 $51,283 $1,053,959 Brook (B)

Warren (T) $54,257 $2,782,554 $60,656,611 0.1 1.1 $1,955,909 $43,426,141 $397,026 $8,160,633

Watchung (B) $22,783 $1,144,069 $25,427,158 0.1 1.2 $738,338 $16,874,711 $321,214 $6,751,946

Somerset County $949,314 $49,112,032 $1,016,264,597 0.1 1.2 $28,710,001 $603,825,222 $8,048,624 $158,816,866 (Total) Source: HAZUS-MH 2.1 RV: Replacement Value *Total is sum of damages for all occupancy classes (residential, commercial, industrial, agricultural, educational, religious and government). **Total replacement value (building and contents) for the County is greater than $83 billion.

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It is estimated that there would be nearly $49 million in damages to buildings in the County during a 500- year earthquake event. This includes structural damage, non-structural damage and loss of contents, representing less than one-percent of the total replacement value for general building stock in Somerset County. For a 2,500-year MRP earthquake event, HAZUS-MH estimates 4,957 buildings will be at least moderately damaged. The estimated total building damage is greater than $603 million, less than one- percent of the total general building stock replacement value (total replacement value is greater than $83 billion for the County). Residential and commercial buildings account for most of the damage for earthquake events.

Earthquakes can cause secondary hazard events such as fires. No fires are anticipated as a result of the 100-, 500- or 2,500-year MRP events.

Impact on Critical Facilities

After considering the general building stock exposed to, and damaged by, 100-, 500- and 2,500-year MRP earthquake events, critical facilities were evaluated. All critical facilities (essential facilities, transportation systems, lifeline utility systems, high-potential loss facilities and user-defined facilities) in Somerset County are considered exposed and vulnerable to the earthquake hazard. Refer to subsection “Critical Facilities” in Section 4 (County Profile) of this Plan for a complete inventory of critical facilities in the County.

HAZUS-MH 2.1 estimates the probability that critical facilities may sustain damage as a result of 100-, 500- and 2,500-year MRP earthquake events. Additionally, HAZUS-MH estimates percent functionality for each facility days after the event. For the 100-Year MRP event, HAZUS-MH 2.1 estimates it is 99% probable that emergency facilities (police, fire, EMS and medical facilities), schools and specific facilities identified by Somerset County as critical (i.e., user-defined facilities such shelters, municipal buildings and Departments of Public Works) will not experience any structural damage. These facilities are estimated to be nearly 100% functional on day one of the 100-year MRP earthquake event. Therefore, the impact to critical facilities is not significant for the 100-year event.

Table 5.4.7-16 and 5.4.7-17 list the percent probability of critical facilities sustaining the damage category as defined by the column heading and percent functionality after the event for the 500-year and 2,500- year MRP earthquake events.

Table 5.4.7-16. Estimated Damage and Loss of Functionality for Critical Facilities and Utilities in Somerset County for the 500-Year MRP Earthquake Event

Percent Probability of Sustaining Damage Percent Functionality Day Day Day Day None Slight Moderate Extensive Complete Name 1 7 30 90 Critical Facilities 93 - EOC 93 - 97 3- 5 < 1 - 2 < 1 0 99 100 100 96 > Medical 99 <1 < 1 0 0 999 100 100 9 93 - Police 96 2 - 5 < 1 - 2 < 1 0 99 100 100 96 93 - Fire 93 - 97 2 - 5 < 1 - 2 < 1 0 99 100 100 97 93 - 98 - Schools 93 - 97 3 - 5 1 - 2 < 1 0 100 100 95 99 93 97 - User Defined 93 - 97 3 - 5 < 1 - 2 < 1 0 100 100 – 99

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Percent Probability of Sustaining Damage Percent Functionality Day Day Day Day None Slight Moderate Extensive Complete Name 1 7 30 90 96 Utilities 99 - Potable Water 97 - 99 < 1 - 2 < 1 0 0 100 100 100 100 98 - Wastewater 97 - 99 < 1 - 2 < 1 0 0 100 100 100 99 98 - Electric Power 97 - 99 < 1 - 2 < 1 0 0 100 100 100 99 Communication 99 < 1 < 1 0 0 99 100 100 100 Source: HAZUS-MH 2.1

Table 5.4.7-7. Estimated Damage and Loss of Functionality for Critical Facilities and Utilities in Somerset County for the 2,500-Year MRP Earthquake Event

Percent Probability of Sustaining Damage Percent Functionality Day Day Day Day None Slight Moderate Extensive Complete Name 1 7 30 90 Critical Facilities 58 - 80– 95 - 97 - EOC 60 - 72 16 - 17 9 - 15 2 - 4 < 1 74 89 98 99 58 - 80 - 97 - Medical 88 80 - 83 34 - 36 < 1 < 1 98 73 88 99 58 - 80 - 97 - Police 60 - 73 16 - 21 9 - 15 2 – 4 < 1 98 73 88 99 60 - 81 - 95 - 98 - Fire 60 - 74 16 - 21 8 - 15 2 - 4 < 1 73 89 98 99 60 - 81 - 95 - 97 - Schools 60 - 74 16 - 21 9 - 15 2 - 4 < 1 74 89 98 99 60 - 81 - 95 - User Defined 58 - 74 16 - 22 2 - 15 2 - 4 < 1 99 74 89 98 Utilities 83 - 98– Potable Water 70 - 85 10 - 16 5 - 12 0 - 1 0 - < 1 100 100 92 99 77 - 97 - Wastewater 70 - 85 10 - 16 5 - 12 0 - 1 0 - < 1 100 100 88 99 77 - 97 - Electric Power 70 - 85 10 - 16 5 - 12 0 - 1 0 - < 1 100 100 88 99 Communication 83 - 84 9 - 10 5 < 1 < 1 97 99 100 100 Source: HAZUS-MH 2.1

Impact on Economy

Earthquakes also have impacts on the economy, including: loss of business function, damage to inventory, relocation costs, wage loss and rental loss due to the repair/replacement of buildings. A Level 2 HAZUS-MH analysis estimates the total economic loss associated with each earthquake scenario, which includes building- and lifeline-related losses (transportation and utility losses) based on the available inventory (facility [or GIS point] data only). Direct building losses are the estimated costs to repair or replace the damage caused to the building. This is reported in the “Impact on General Building Stock” section discussed earlier. Lifeline-related losses include the direct repair cost to transportation and utility systems and are reported in terms of the probability of reaching or exceeding a specified level of damage when subjected to a given level of ground motion. Additionally, economic loss includes business interruption losses associated with the inability to operate a business due to the damage sustained during the earthquake as well as temporary living expenses for those displaced. These losses are discussed below.

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It is significant to note that for the 500-year event, HAZUS-MH 2.1 estimates the County will incur approximately $7.54 million in income losses (wage, rental, relocation and capital-related losses) in addition to the 500 –year event structural, non-structural and content building stock losses ($49 million). For the 2,500-year event, HAZUS-MH 2.1 estimates the County will incur nearly $123 million in income losses, mainly to the residential and commercial occupancy classes associated with wage, rental, relocation and capital-related losses.

The HAZUS-MH analysis conducted did not compute any damage estimates for roadway segments and railroad tracks. However, it is assumed these features may experience damage due to ground failure and regional transportation and distribution of these materials will be interrupted as a result of an earthquake event. Losses to the community that result from damages to lifelines can be much greater than the cost of repair (HAZUS-MH 2.1 Earthquake User Manual, 2012).

Earthquake events can significantly impact road bridges. These are important because they often provide the only access to certain neighborhoods. Since softer soils can generally follow floodplain boundaries, bridges that cross watercourses should be considered vulnerable. A key factor in the degree of vulnerability will be the age of the facility, which will help indicate to which standards the facility was built.HAZUS-MH estimates the long-term economic impacts to the County for 15-years after the earthquake event. In terms of the highway transportation infrastructure, HAZUS-MH estimtes $22 Million in direct repair costs to bridges in the County as a result of a 2,500-year event. No loss is estimated for highway segments

It is estimated that the rail stations and airports in Somerset County will be 70 - 85% functional on day one of the 2,500-year event and an estimated 11- to 15-percent probability they will experience slight damage.

HAZUS-MH 2.1 also estimates the volume of debris that may be generated as a result of an earthquake event to enable the study region to prepare and rapidly and efficiently manage debris removal and disposal. Debris estimates are divided into two categories: (1) reinforced concrete and steel that require special equipment to break it up before it can be transported, and (2) brick, wood and other debris that can be loaded directly onto trucks with bulldozers (HAZUS-MH Earthquake User’s Manual).

For the 100-year MRP event, HAZUS-MH 2.1 estimates 0 tons of debris will be generated. For the 500- year MRP event, HAZUS-MH 2.1 estimates more than 20,000 tons of debris will be generated. For the 2,500-year MRP event, HAZUS-MH 2.1 estimates greater than 265,006 tons of debris will be generated.

Table 5.4.7-17. Estimated Debris Generated by the 500- and 2,500-year MRP Earthquake Events

500-Year 2,500-Year Brick/Wood Concrete/Steel Brick/Wood Concrete/Steel Municipality (tons) (tons) (tons) (tons) Bedminister (T) 929 375 8,934 7,713 Bernards (T) 1,686 429 16,684 8,460 Bernardsville (B) 435 106 4,477 2,012 Bound Brook (B) 298 77 3,100 1,533 Branchburg (T) 1,503 604 15,091 13,599 Bridgewater (T) 2,027 578 21,349 11,938 Far Hills (B) 90 32 926 639 Franklin (T) 2,696 851 28,651 18,093 Green Brook (T) 334 84 3,525 1,692 Hillsborough (T) 1,611 474 17,165 9,748

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500-Year 2,500-Year Brick/Wood Concrete/Steel Brick/Wood Concrete/Steel Municipality (tons) (tons) (tons) (tons) Manville (B) 362 97 3,629 2,002 Millstone (B) 16 3 169 53 Montgomery (T) 1,120 267 11,681 5,105 North Plainfield (B) 604 153 6,247 3,155 Peapack Gladstone (B) 157 47 1,614 931 Raritan (B) 299 108 3,167 2,279 Rocky Hill (B) 37 10 394 191 Somerville (B) 432 126 4,507 2,628 South Bound Brook (B) 98 24 1,019 474 Warren (T) 939 220 9,894 4,370 Watchung (B) 389 99 4,170 2,056 Somerset County (Total) 16,065 4,764 166,394 98,672 Source: HAZUS-MH 2.1

Future Growth and Development

As discussed in Section 4, areas targeted for future growth and development have been identified across the County. It is anticipated that the human exposure and vulnerability to earthquake impacts in newly developed areas will be similar to those that currently exist within the County. Current building codes require seismic provisions that should render new construction less vulnerable to seismic impacts than older, existing construction that may have been built to lower construction standards.

New development located in areas with softer NEHRP soil classes may be more vulnerable to the earthquake hazard. Refer to 3 for potential new development and approximate NEHRP soil class areas in Somerset County. Some potential new development is located with approximate NEHRP soil class ‘D’.

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Figure 5.4.7-1. Potential New Development in Somerset County and NEHRP Soil Types

Source: FEMA, 2009 Note: To estimate the location of the NEHRP soils, FEMA floodplains were classified as soil type D with the remainder of the County soil type C for the purposes of this risk assessment.

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Change of Vulnerability

The earthquake hazard was not evaluated as part of the 2008 original HMP. As summarized in Section 5.2 (Hazards of Concern) the NJ State HMP identifies earthquake as a hazard of concern for the state of New Jersey. According to the USGS online seismic hazard maps, the peak ground acceleration with a 10% probability of exceedance over 50 years for Somerset County is between 2 and 3% g. FEMA guidance recommends earthquakes are evaluated further if an area has a 3% g peak acceleration or more. Somerset County decided to evaluate the earthquake hazard as part of their HMP update.

Effect of Climate Change on Vulnerability

The impacts of global climate change on earthquake probability are unknown. Some scientists say that melting glaciers could induce tectonic activity. As ice melts and water runs off, tremendous amounts of weight are shifted on the earth’s crust. As newly freed crust returns to its original, pre-glacier shape, it could cause seismic plates to slip and stimulate volcanic activity according to research into prehistoric earthquakes and volcanic activity. NASA and USGS scientists found that retreating glaciers in southern Alaska may be opening the way for future earthquakes (NASA, 2004).

Secondary impacts of earthquakes could be magnified by climate change. Increased saturation of soils by more frequent and/or intense storms could increase the risk for liquefaction. Dams storing increased volumes of water due to changes in the hydrograph could fail during seismic events. There are currently no models available to estimate these impacts. Additional Data and Next Steps

A Level 2 HAZUS-MH earthquake analysis was conducted for Somerset County using the default model data, with the exception of the updated building and critical facility inventories which included user- defined data, and estimated modification to the NEHRP soil data. Additional data needed to further refine the County’s vulnerability assessment include: (1) updated demographic data to update the default data in HAZUS-MH; (2) soil liquefaction data; and (3) the NEHRP soil data from the New Jersey Geologic and Water Survey. Additionally, the County can identify un-reinforced masonry critical facilities and privately-owned buildings (i.e., residences) using local knowledge and/or pictometry/orthophotos. These buildings may not withstand earthquakes of certain magnitudes and plans to provide emergency response/recovery efforts for these properties can be set in place. Further mitigation actions include training of County and municipal personnel to provide post-hazard event rapid visual damage assessments, increase of County and local debris management and logistic capabilities, and revised regulations to prevent additional construction of non-reinforced masonry buildings.

DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey 5.4.7-40 August 2013