The 2008 Wenchuan earthquake in Sichuan, China, killed tens of thousands of people and left millions homeless. About 20,000 deaths -- nearly 30 percent of the total -- resulted not from the ground shaking itself but from the landslides that it triggered.
A model developed by a team of researchers, including PhD candidate Hakan Tanyas of the ITC Faculty of Geo-information Science and Earth Observation of the University of Twente, can help experts address such risks by estimating the likelihood of landslides that will be caused by earthquakes anywhere in the world. The estimates can be available within minutes, providing potentially life-saving information to people who are affected by earthquakes and the agencies and organizations charged with responding to them.
"Earthquakes can be devastating, horrific and stressful events," said Anna Nowicki Jessee, postdoctoral research fellow at the Indiana University’s Bloomington College of Arts and Sciences'. "The ultimate goal of this work is that fast, regional estimates of landslide occurrence would provide a way for those who are affected to receive the aid they need more quickly and efficiently."
U.S. GEOLOGICAL SURVEY'S GROUND FAILURE TOOL
The model, based on data from past earthquakes and landslides, will be incorporated into the U.S. Geological Survey's Ground Failure tool, which will be part of the USGS earthquake reporting system. A paper describing the model has been published in the Journal of Geophysical Research: Earth Surface.
The model describes a mathematical relationship between where landslides happen and five key variables: how much the ground shook during an earthquake; the steepness of the ground; the type of rock affected; an estimate of how wet the ground is; and what type of land cover is present. The researchers tested multiple versions based on past earthquake-triggered landslides and selected the model with predictions that best matched where landslides occurred.
By entering data for ground shaking for a specific earthquake -- available anywhere around the globe from the U.S. Geological Survey ShakeMap tool -- scientists will be able to use the model to produce a map showing the probability of landslides in areas near the quake. Available within minutes, the results could provide this information quickly to agencies that assist affected populations.
The model has been built based on the worldwide database of earthquake‐induced landslide inventories, which was presented last year by Hakan Tanyas and his colleagues. Tanyas: “We have been collaborating for a while and we gathered the largest database regarding earthquake-induced landslides. We also developed a web-based platform to make the data publicly available. The database we gathered helped us to develop such a model. This may become a useful tool for near real-time hazard assessment regarding earthquake-induced landslide in the near future .”
Landslides are the third-largest contributor to earthquake deaths, after building collapse and tsunamis. From 2004 to 2010, earthquake-induced landslides caused an estimated 47,000 deaths. Damaging quakes often occur in remote and mountainous regions with limited transportation and communication networks, where landslides can block roads and impede emergency-response and relief efforts.
"The best part for me," Jessee said, "is the idea that this product can be used to actually help people who are impacted by landslides caused by earthquakes."