Years participated in RESESS:
Influence of lithology, proximity to fault rupture, and ground motion on the distribution of landslides generated by the May 12th, 2008, Mw 7.9 China earthquake
Academic Affiliation: Senior, University of Puerto Rico at Mayaqüez, Geology
Science Research Mentors: Jonathon Godt, USGS, Valerie Sloan, UNAVCO
Writing Mentor: Beth Bartel, UNAVCO
Habib Bravo Ruíz lives in Aguadilla, Puerto Rico, and is a college senior. Habib's love of nature and science led him to study geology. Habib has excelled at the University of Puerto Rico in Mayaqüez and has received multiple academic awards and scholarships. Habib's goal is to attend graduate school in the field of hydrology and to teach geology. Habib is known amongst his friends for his appreciation of pastry chefs.
The magnitude 7.9 earthquake in Wenchuan, China, on May 12th, 2008, triggered tens of thousands of landslides. Landslides were responsible for 20,000 of the nearly 90,000 fatalities. Landslides also dammed several rivers and heavily damaged public infrastructure and private property in the region. This paper examines the effect of the geologic setting on the number and area of the landslides in a 325-km2 area near the epicenter. A total of 3,561 landslides were digitized using ArcGIS 9.3 from 60-cm resolution Quickbird optical satellite imagery. The distribution and density of landslides were compared with mapped lithology, fault rupture, and with estimates of distribution of peak ground acceleration (PGA), peak ground velocity (PGV), and Modified Mercali Index (MMI) from the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) project. Thematic data layers of lithology and proximity to fault rupture were prepared using a 1:1,000,000 geologic map. The results indicate that the abundance of landslides does not decrease linearly with distance from the fault rupture, as expected, but are more common 10-15 km away from the main fault rupture where the lithology consists of weaker rock types. This area is underlain by weathered Proterozoic metamorphic and Silurian sedimentary rocks. In terms of the relationship between ground motion and abundance of landslides, we found that the results of the PAGER system are moderately correlated with landslide distribution. These findings are being used to test a regional landslide model under development in the PAGER system and to manage future earthquake-induced landslide hazards in the region.