2010 Alum

Arlenys Ramirez

Arlenys Ramírez

Years participated in RESESS:

An Overview

Topographic influence on the distribution of landslides triggered by the 2008 Wenchuan earthquake, China

Academic Affiliation: Senior, University of Puerto Rico, Mayaqüez, Geology
Science Mentors: Jonathan Godt, USGS, and Valerie Sloan, UNAVCO
Writing Mentor: Sharon Diehl, USGS


Arlenys Ramirez was born in San Juan, Puerto Rico, and grew up in Carolina, Puerto Rico. While fashion modeling was her passion, she decided to leave that world to become a geoscientist. Her interest in geology began when she was young but internsified when she took an introductory science course at college with a chapter about general geology. The next year she transferred to the University of Puerto Rico at Mayaüez to study geology. Arlenys plans to attend graduate school next year, and one of her goals is to do research in the mainland U.S. Her research interests are in landslides and field-based research related to geophysics, geological hazards, and GPS geodesy.


On May 12, 2008, a major earthquake occurred at the eastern margin of the Tibetan plateau in the province of Sichuan, China. The Mw 7.9 earthquake generated fault ruptures that extended more than 270 km along the Yingxui-Beinchuan fault system and produced tens of thousands of landslides. The landslides caused massive destruction and were responsible for about 20,000 of the nearly 90,000 deaths attributed to the earthquake. We examined the influence of topographic slope and aspect as well as distance from the epicenter on the distribution and density of landslides in two study areas in the epicentral region.

Landslides triggered by the earthquake were mapped from optical satellite imagery with 60-cm resolution. Topographic slope and aspect were calculated from Shuttle Radar Topography Mission (SRTM) 90-m digital elevation data.

We also compared landslide density with a model that predicts the distribution of landslides produced by large earthquakes in mountainous regions. The model is being developed as part of the U.S. Geological Survey Prompt Assessment of Global Earthquakes for Response (PAGER) system. Results show that the number and density of landslides decreases with distance from the epicenter. In the study area the density of landslides tends to be greatest on southeast facing slopes that are inclined between 30° and 50°.

Comparisons of mapped landslides with preliminary results from the PAGER landslide module showed that the accuracy of this landslide module to predict the likelihood of the landslides was only 30% in the northern region and 28% in the southern region.