EERI Special Earthquake Report — April 2010 Learning from Earthquakes The Mw 7.0 Haiti Earthquake of January 12, 2010: Report #1 This is the first of multipleNewsletter The EERI contribution was funded Rico to the east and Jamaica and inserts on the Haiti earthquake of by the Learning from Earthquakes Cuba to the west, and has a total January 12, 2010. It summarizes project of the National Science Foun- population of approximately 9 mil- observations from the advance dation under Award #CMMI-0758529. lion. Its largest city, Port-au-Prince, team organized by the U.S. Geo- with an estimated population of be- logical Survey (USGS) and EERI Introduction tween 2.5 and 3 million people, is that traveled to Haiti January 26 to located 25 km ENE of the epicen- The Mw 7.0 earthquake that struck February 3, 2010. The multidiscip- ter. Haiti is the poorest country in the Republic of Haiti on January 12, linary team included Marc Eberhard, the Western Hemisphere, with an 2010, is among the most destructive University of Washington (team estimated 80% of its people living earthquakes in recorded history. As leader); Steve Baldridge, Baldridge under the poverty line, 54% in ab- of March 2010, the death toll report- & Associates Structural Engineer- ject poverty (CIA, 2010). In 2008, ed by the Government of Haiti ex- ing, Inc.; Justin Marshall, Auburn more than 800 people were killed ceeded 233,000, with an additional University; Walter Mooney, USGS; by four hurricanes and tropical 300,000 injuries. More than 5 million and Glenn Rix, Georgia Institute of storms that struck during a two- people live in the area affected by the Technology. month period. earthquake, 1.2 million of whom are In addition to earthquake damage now in temporary shelters (United reconnaissance, the team installed Nations, 2010). Humanitarian relief Seismology four seismograph stations; partici- agencies continue to be challenged Despite recent seismic quiescence, pated in assessments of numerous by the scale of the disaster. Haiti has suffered similar devastat- buildings, bridges, and port facilities; ing earthquakes in the historic past The Republic of Haiti occupies the and trained engineers in post-earth- (1701, 1751, 1770, and 1860). Haiti western third (27,750 km2) of the quake damage assessment. had no seismograph stations during island of Hispaniola, located in the the main earthquake, so it is difficult The reconnaissance effort was NE Caribbean between Puerto made possible by the logistical support of the U.S. Southern Com- mand and the officers, soldiers, marines, airmen, and civilians of Joint Task Force Haiti. The institu- tional support of the U.S. Embassy and U.S. Agency for International Development was also crucial. Travel funding for the team was provided by the USGS, EERI, Net- work for Earthquake Engineering Simulation (NEES), Geo-Engineer- ing Extreme Events Reconnais- sance (GEER) Association, and Applied Technology Council (ATC). This insert also includes a section on search and rescue operations by Mikaël Gartner, Donny Harris, Bruce Cook, and Keith Martin, structural specialists with the USAID/OFDA Urban Search and Rescue Team (US-2 / CA-TF2), Figure 1. Topographic map of Haiti with the January 12, 2010, main shock operated by the Los Angeles (M7 star) and aftershocks (M5-6 orange and M4-5 yellow) in the first two County Fire Department. weeks. Many aftershocks struck 40-50 km west of the main shock, at the west end of the subsurface fault rupture (USGS, 2010). 1 EERI Special Earthquake Report — April 2010 to estimate accurately the intensity 2). The earthquake source zone (the field investigations failed to find of ground motions. Nonetheless, surface area of the fault that slipped) any evidence of surface faulting. the wide range of buildings dam- is quite compact, with a down-dip Numerous cracks in roadways aged suggests that the ground mo- dimension of approximately 15 km could all be attributed to slumping tions contained seismic energy and an along-strike dimension of 30 of road embankments, which rise over a wide range of frequencies. km. This source dimension is about as much as 3 m (9.8 ft) above the Another earthquake of similar mag- one-third the size of a typical Mw 7.0 adjoining fields. We concluded that nitude could strike at any time on earthquake. The earthquake rupture surface faulting is unlikely in the the eastern end of the Enriquillo was very abrupt and sharp; maximum region west of the epicentral zone fault, directly to the south of Port- moment release occurred in the first near the town of Fayette and up to, au-Prince. Reconstruction must 10 seconds of the fault slip. and including the coastline west of take this hazard into account. the town of Dufort. The four portable seismographs in- Main Shock and Aftershocks. stalled by the team recorded a series The January 12 quake struck at of small aftershocks. As expected, the Geotechnical Aspects 04:53 PM local time. The USGS ground motions recorded at a hard Soil liquefaction, landslides and epicenter was 18.457° N, 72.533° rock site had a greater proportion of rockslides in cut slopes, and road W, 25 km WSW of Port-au-Prince high frequencies than the motions embankment failures contributed to on or near the Enriquillo fault (Fig- recorded at a soil site. Two of the extensive damage in Port-au-Prince ure 1). The estimated depth was stations continue to monitor seismic and elsewhere. More complete 13 km, but the lack of local seismic activity. coverage of these aspects can be data makes the precise depth un- found in the GEER report, men- Surface Faulting. Many crustal certain. The USGS assigned a tioned at the end of this insert. earthquakes of Mw 7.0 or greater are horizontal uncertainty of +/- 3.4 accompanied by surface rupture that Liquefaction-induced lateral km. The focal mechanism for the can be traced for tens of kilometers. spreading contributed greatly to the main shock indicates left-lateral However, U.S.-based remote sensing extensive damage in Port de Port- oblique-slip motion on an east-west experts have reported no success au-Prince, especially the collapse oriented fault. The fault ruptured in identifying surface rupture from of a pile-supported marginal wharf. from east to west, away from Port- satellite imagery. Land-based inves- The liquefaction features and au-Prince and towards the cities of tigations by other scientists conduct- resulting damage are described in Léogâne, Grand Goâve, and Petite ed between January 22 and 26 more detail in a subsequent section Goâve. The USGS finite-fault mod- identified only roadway cracking and of this report on the port. el shows a maximum slip of 5 m slumping, no surface ruptures. Our up-dip from the hypocenter (Figure Other less severe liquefaction- related features were observed in the alluvial plain surrounding the city of Léogâne. Figure 3 shows the failure of a structure located about 75 m (246 ft) from the shoreline at 18.446323° N, 72.686259° W. There were several sand boils nearby, the largest of which mea- sured approximately 4 m (13 ft) in diameter. Based on discussions with others who observed this structure (Rathje and Green, 2010), it is likely that a combination of structural and foundation failures contributed to the collapse. A lack of detailed knowledge about soil physical conditions (lithology, stiffness, density, and thickness) made it difficult for us to assess quantitatively the role of ground- Figure 2. USGS finite-fault model indicates the amount of slip on the fault motion amplification in the wide- plane during the earthquake. West is to the right (Hayes, 2010). spread damage. 2 EERI Special Earthquake Report — April 2010 indicated that 28% had collapsed and another 33% were damaged enough to require repairs. A similar survey of 52 buildings in Léogâne, the closest large population center to the epicenter, found that 62% had collapsed and another 31% required repairs. It appears that the widespread damage to residences and com- mercial and government buildings was largely attributable to the lack of attention to seismic risk in design and construction. In a country as poor as Haiti, typical residences and commercial buildings are con- structed informally, with whatever materials and procedures can be afforded. Such structures have not Figure 3. Combined structural and foundation failure southwest of Léogâne. usually been designed formally. For most larger commercial and Structures ed is a discussion of prefabricated government buildings that were steel frame performance and a quan- more likely to have been designed The earthquake caused extensive titative survey of distributed damage by an engineer, the structural types, damage to buildings throughout the for two sample areas. Below are high- member dimensions, and detailing Port-au-Prince region, and in the lights from the more comprehensive practices were inadequate to resist rural areas and towns to the west report. strong ground motions. These of the city. The larger report pre- vulnerabilities may have been ex- pared by this team and available The Haitian Ministry of Statistics and acerbated by poor construction on the web (http://www. Informatics reported that one-story practices and difficulties in the eqclearinghouse.org/20100112- buildings represent 73% of the build- procurement of consistent quality haiti/published-reports) provides ing inventory. Most typical one-story construction materials (Figures 4 an overview of Haitian building houses have roofs made of sheet and 5). and housing statistics, typical con- metal (82%), whereas most multi- Reinforced concrete frames with struction practices, and damage to story houses and apartments have concrete block masonry infill ap- residential construction. It de- roofs made of concrete (71%). Walls peared to perform particularly poor- scribes the performance of rein- made of concrete/block/stone pre- ly.