Fresh Fault Ruptures Studied with 3D Models

By comparing pictures and computer models of areas neighboring fault lines – taken both before and after a major earthquake occurs – scientists can now gain a deeper understanding of how these sectors of Earth's crust move and interact during seismic events.

Such investigations could come in very handy in the long run, experts say, primarily because the movement of tectonic plates at and around fault lines is not very well understood. Until now, the necessary means to conduct such investigations were lacking.

At this time, geologists can use GPS measurements that are so precise they can reveal even minute ground motions. Similar systems are already in use in certain areas of the world where landslide risk is enormous. They are also used to measure how fast continents drift apart from each other.

The new approach is detailed in this week's issue of the top journal Science. The work was carried out by a group of investigators in China, the United States and Mexico. Their data covered an earthquake that occurred in 2010, near Mexicali, Mexico. The event had a magnitude of 7.2.

Thankfully, investigators were able to collect images of the fault line that ruptured both before and after the actual event. “We can learn so much about how earthquakes work by studying fresh fault ruptures,” explains University of California in Davis (UCD) geologist and leaf paper author Michael Oskin.

The photos and 3D models were compiled from advanced light detection and ranging (LIDAR) measurements. A LIDAR instrument was provided by the National Center for Airborne Laser Mapping (NCALM). The Mexican fault line was chosen for a practical reason.

Scientists knew that the Mexican government had conducted a LIDAR study campaign of its own over the same area, back in 2006. By gaining access to those datasets, investigators were able to compare their new measurements with their old ones.

The research was made possible through a rapid-response grant provided by the US National Science Foundation (NSF) to Oskin and Arizona State University expert Ramon Arrowsmith. “This study is an excellent demonstration of an emerging tool for Earth science,” Greg Anderson explains.

The official holds an appointment as a director for the NSF EarthScope program, through which the research was supported. The new data are currently being analyzed, but early results indicate that they may contribute to furthering our understanding of how multi-fault earthquakes are produced.

NASA, the US Geological Survey (USGS), and National Council of Science and Technology in Mexico also supported the investigation.