News from the Field: Day 6--Hilton Creek Fault and Geophysical Experiment

Two new guests joined us today: Sue Owen and Eileen Cooper from the University of Southern California--geophysicists who are studying active deformation of Long Valley using Global Positioning System (GPS) measurements. We spent part of the morning at SNARL, reviewing Sue's current research on active deformation in and around Long Valley. We then headed out to McGee Creek, a beautiful glacial valley on the edge of the high Sierra. McGee Creek also has the honor of hosting a beautiful example of an active normal fault, the Hilton Creek Fault, which shows active offsets as it cuts across a young glacial moraine. Sue brought with her some state-of-the-art geophysical equipment--GPS receivers, a high-precision gravity meter, and a magnetometer. We learned how to set up, operate, and analyze data from these geophysical instruments. At the end of the afternoon, we climbed to the fault scarp, examining evidence for recent movement along the fault. Another great dinner back at SNARL, followed by a quiet evening back at the dorm.

Mariel Berger and John Schuman stoke up for the day with a hearty breakfast.
Sue Owen (University of Southern California) explains her research on volcano-tectonic deformation of the Long Valley Caldera
En route to the McGee Creek Valley, John and Sue stop to give an overview of the Hilton Creek Fault.
Mike Hamburger and Sue Owen discuss the basics of GPS instrument setup
Michael shows how to set up the GPS tripod
And Sue Owen explains how the antenna works
Curtis Williams, Caroline Pew, and John Schuman try their hand at it
And Neal, Sarah, and Brian figure out how to program the receiver
Neal Solon points to one of the GPS satellites, while Brian Moore looks on
And the group gets in position to get a better view!
Sue Owen shows Laura Dunn how to run a gravity meter.
And Adam Schau and Leah French try out the magnetometer
And start off on their profile across the fault...
A climb up the moraine for a striking (and along-strike!) view of the Hilton Creek Fault
After dinner, a quiet game of chess for Adam and Leah
And a noisy game of cards for the others!