Monday, October 8, 2012

Hector Mine 1999 surface rupture

A group of us spent this past week (Oct. 1 - 5, 2012) back out at the Marine Corps Air Ground Combat Center (MCAGCC) in 29 Palms, CA re-investigating the 1999 surface faulting of the Hector Mine earthquake. We went into the Rainbow Canyon section of the base to work along the part of the fault that had the most slip. We're excited about what we discovered, including a location that seems to have had even more slip than had been measured by others back in 1999-2000. Recently, NCALM acquired new airborne LiDAR data that we'll use to compare with the original post-earthquake airborne LiDAR we obtained in April 2000. We are studying slip distribution, variation, and also fault scarp degradation processes. How landforms evolve along an active fault tells us about how long ago their last big earthquake was, and how active and hazardous a particular fault may be. Having a chance to study earthquake landform evolution in the earliest several years is especially instructive for us, and because this earthquake was on an "off limits" military base, it has actually been preserved especially well over the years. Participants this week included Prof. Joann Stock of Caltech and two graduate students, Frank Sousa & Janet Harvey, as well as Katherine Kendrick and Kate Scharer of USGS. We have taken all of the required safety training, obtained our badges for base access, and requested additional access from the MCAGCC over the upcoming months to continue these studies. This is an opportunity to use high-resolution, state-of-the-art airborne imagery to make special quantitative studies of extreme slip variation and 3D fault scarp degradation.