Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures 3.11 Geology/Soils/Seismic/Topography The information in this section is based on the Preliminary Geotechnical Design Report (Kleinfelder, 2008.) 3.11.1 Regulatory Setting For geologic and topographic features, the key federal law is the Historic Sites Act of 1935, which establishes a national registry of natural landmarks and protects “outstanding examples of major geological features.” Topographic and geologic features are also protected under the California Environmental Quality Act. This section also discusses geology, soils, and seismic concerns as they relate to public safety and project design. Earthquakes are prime considerations in the design and retrofit of structures. The Department’s Office of Earthquake Engineering is responsible for assessing the seismic hazard for Department projects. The current policy is to use the anticipated Maximum Credible Earthquake (MCE), from young faults in and near California. The MCE is defined as the largest earthquake that can be expected to occur on a fault over a particular period of time. The Alquist-Priolo Earthquake Fault Zoning Act was passed by the State of California in 1972 to mitigate the hazard of surface faulting to structures for human occupancy. The Alquist-Priolo Earthquake Fault Zoning Act’s main purpose is to prevent the construction of buildings used for human occupancy on the surface trace of active faults. The Act only addresses the hazard of surface fault rupture and is not directed toward other earthquake hazards. The Seismic Hazards Mapping Act, passed in 1990, addresses nonsurface fault rupture earthquake hazards, including liquefaction and seismically induced landslides. The law requires the State Geologist to establish regulatory zones (known as Earthquake Fault Zones1) around the surface traces of active faults and to issue appropriate maps. The maps are distributed to all affected cities and counties and state agencies for their use in planning and controlling new or renewed construction. 1 “Earthquake Fault Zones” were called “Special Studies Zones” prior to January 1, 1994. Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation 3.11-1 Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures 3.11.2 Affected Environment California comprises 11 geomorphic provinces as defined by the California Department of Mining. The MCP study area is located within the Peninsular Ranges Geomorphic Province. The Peninsular Range province is a series of mountain ranges separated by northwest-trending valleys running parallel to faults branching from the San Andreas fault. The Peninsular Ranges extend south to Mexico and are bordered by the Transverse Ranges on the north, the Colorado Desert on the east, and the Pacific Ocean on the west. 3.11.2.1 Local Geology/Topography There are no designated National Natural Landmarks within the MCP study area. As shown in Figure 3.11.1, the far western portion of the MCP study area is located within the northwest-trending Temescal Valley, bounded by the Santa Ana Mountains on the west and the east by the Perris Block (a structural geologic block bounded by faults and fault systems). Natural landmarks help define the topography of the MCP study area, which ranges from moderately rugged to gently rolling hills in the west, transitioning to flat, open, ruderal and agricultural lands in the east. The most distinct landmarks within the western portion of the MCP study area include Monument Peak and Gavilan Peak, part of the Gavilan Hills. Monument Peak is 744 meters (m) (2,442 feet [ft]) above sea level, while Gavilan Peak, which is about 5 kilometers (km) (3 miles [mi]) east of Monument Peak, is 711 m (2,333 ft) above sea level. Continuing east in the MCP study area, the Bernasconi Hills are a distinct natural landmark of the Lake Perris area. Trending northeast and located approximately 9 km (6 mi) northeast of Perris, the elevation of the Bernasconi Hills is approximately 808 m (2,647 ft) above sea level. The McCanna Hills lie south of Lake Perris, directly south of the Ramona Expressway. These are relatively low lying hills with an elevation of approximately 518 m (1,700 ft) above sea level. The northern portion of the Lakeview Mountains is one of the most distinctive landmarks in the eastern MCP study area. Mount Rudolph, a prominent feature at the northerly end of the range, rises to an elevation of 791 m (2,595 ft) above sea level. 3.11-2 Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation ?¼E ?zE ?«E ?ÆE a River Santa An S a n J a ?zE c i n t o M o !"a$ u n t e y a a l l Mount Russell i n V s o M n Mount Eden oc e ki r n o ?ÆE gb on ir M ny d a Arlington Mountain C C a Three Sisters e on ny %&h( rd y n o o an o n b y a C n n s L b o a y l y n l m e n i i a C l Lake L a l l a H C a r i !"a$ P a n re sc V Perris D o c e Mead Valley e c a Lake s s m i s s r m a e r a r T Mathews r Coney Hill n r o r M e Colo t e rado River Aque i d P uc S t B s ?¹E Cajalco Canyon V a S l a l r Mount Rudolph e n e v McCanna Hills J y Ri a T Gavilan Peak o t c e in i m c n a t e Monument Peak J o S a n s a V c S n San Jacinto a t a l a l Lakeview Mountains Reservoir l V e A y n a ?±E a l Estelle Mountain l M e o y u n Steele Peak t a i n s ?±E Canyon Lake M e n i f e e V a l l e y Diamond Valley Lake AHÎ Legend Elevation Figure 3.11.1 Study Area Right-of-Way (Alternative 9) ft ft Right-of-Way (Alternatives 4,5,6 and 7) 00 ft 00 00 ft 00 ,2 ,0 0-400 ft -1,6 -3,2 401-800 ft 1 800-1 01 01-2 001-2,400 ft 1,2 1,6 2, 2,401-2,8002,80 ft SOURCE: USGS (2006), Jacobs Engineering (2/2007), TBM (2007) 0361.5 Miles Landforms and Topographic Features 0512.5 0Kilometers KP 0.0/51.0 (PM 0.0/31.7) EA 08-0F3200 I:\JCV531\GIS_Final\EIR_EIS\20080402_EIR_EIS_Final\Landforms_TopograpihcFeatures_100807.mxd (8/6/2008) Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures This page intentionally left blank 3.11-4 Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures The topography from Temescal Valley eastward to Lake Mathews is characterized as mountainous terrain with moderately rugged slopes and well-cut drainage channels. Lake Mathews is a man-made lake formed by damming a naturally occurring valley at the head of Cajalco Canyon. The area surrounding the lake is an irregular plateau with gently rolling hills and tributary channels. The area just east of Lake Mathews and on the western side of Perris Valley is characterized by moderate relief and gently rolling hills. Mead Valley is located in this area, separated from the Perris Valley by low hills along the eastern margin. Perris Valley is a 6 to 8 km (4 to 5 mi) wide, alluvial-filled basin that extends from Moreno Valley on the north to Menifee Valley on the south. The Bernasconi Hills define the eastern border of the Perris Valley, separating it from the San Jacinto Valley. The San Jacinto River floodplain is located within a northeast-trending valley between Perris Valley and the San Jacinto Valley, bordered by the Bernasconi Hills on the west and the Lakeview Mountains on the southeast. The San Jacinto River flows toward the Elsinore Valley approximately 32 km (20 mi) to the southwest. The eastern end of the MCP study area is within the San Jacinto Valley. The San Jacinto Valley is an alluvial valley along the San Jacinto fault zone. 3.11.2.2 Faulting/Seismicity The entire southern California region is seismically active due to the influence of several earthquake fault systems resulting from interaction between the Pacific and North American crustal plates. An active fault is defined by the State of California as a “sufficiently active and well defined fault that has exhibited surface displacement within the last 11,000 years.” A potentially active fault is defined by the State as a “fault with a history of movement between 11,000 and 1.6 mya” (million years ago). These active and potentially active faults are capable of producing seismic shaking within the MCP study area that could be damaging to bridges and other structures. Figure 3.11.2 illustrates the major fault zones in the MCP study area. Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation 3.11-5 Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures This page intentionally left blank 3.11-6 Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation San Bernardino County Los Angeles County Cucamonga Fault Zone %&h( ?àE Sa n An drea s Fa %&g( %&g( %&g( ult Z IÀ one !"`$ S %&h( an ?zE J ac ?zE in ?¼E to F C ?«E au hin lt o F Z a o ?uE ult ?ÆE %&h( ?zE n Zo e ne ?àE !"`$ ?¹E ?ÆE C a AHÎ W sa ?sE h it L t o ier m ?ìE / a !"^$ E ?àE ?±E F AHÝ ls au ?±E l in t Z o o %&l( ?sE re n ?±E F e au lt y Z AìH AHÎ t o %&h( n n ou y e C t n e u !"^$ g o ?¹E ?°E n a C r e O id s ?±E r e iv R ?¹E Legend Figure 3.11.2 Fault Zone Mid County Parkway Study Area County Boundary SOURCE: California Department of Conservation (1997 ), ESRI (2006), Jacobs Engineering (2/2007), LSA (2007) 05102.5 Miles Fault Zones 08164Kilometers KP 0.0/51.0 (PM 0.0/31.7) EA 08-0F3200 I:\JCV531\GIS_Final\EIR_EIS\20080402_EIR_EIS_Final\GeologicFaults_100807.mxd (4/23/2008) Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures This page intentionally left blank 3.11-8 Draft Mid County Parkway EIR/EIS and Section 4(f) Evaluation Chapter 3 Affected Environment, Environmental Consequences, and Mitigation Measures There are several major active fault zones capable of generating ground shaking during a seismic event which could impact the MCP study area: the San Jacinto fault zone (which includes the Casa Loma fault), located near the eastern end of the MCP study area; and the Whittier/Elsinore fault zone, located near the western end of the MCP study area.