Mike Oskin (@mikeoskin) from U.C. Davis tweeted on late Sunday that PhD students Alex Morelan and Chad Trexler had gone out in the field in the Napa area and mapped several surface ruptures related to the South Napa earthquake of Aug 24, 2014. Additional tweets showed pictures of the ruptures.

16 km of rupture, max slip of 25 cm. Thanks to Alex Morelan and Chad Trexler for all the hard work today! #napaquake pic.twitter.com/aukcZIns2N

— Mike Oskin (@mikeoskin) August 25, 2014

Surface rupture zone about 1/2 km wide through Brown's Valley. Seems to be a stepover on the fault. #napaearthquake pic.twitter.com/gQEzwLEQz4

— Mike Oskin (@mikeoskin) August 25, 2014

Chad Trexler measuring 24 cm displacement across west Napa fault at Oak Rock Drive. #napaquake https://t.co/F2VMSE4odN

— Mike Oskin (@mikeoskin) August 25, 2014

Update: Here is an announcement regarding surface rupture mapping by USGS geologists: Update on the Magnitude 6 South Napa Earthquake of August 24, 2014