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I added a few photos from Alex Morelan to this KMZ. Rupture (red) lines are my rough interpretations connecting observation points. The north end of the rupture zone is quite broad and I did not make an attempt to connect the dots there.
cool to see the rupture zone!
Alex Morelan and Chad Trexler (UCD Ph.D. students) tracked the surface rupture north and south of highway 12. Total length observed is 16 km. Could extend offshore a bit to the south but slip was below 3 cm at that point. North end is a complex stepover, with some left lateral faulting, ending in cracking along the scarp in Alston Park. This is where Dawson recently trenched and did not find a fault. So nature says otherwise! I'm posting a pic and a KML. I have pictures for each site, but Alex and Chad have the complete data set.
I quickly georeferenced map B from Wesling and Hanson and upload it here as a kmz.
The rupture observations that Mike posted are along the West Napa fault zone, Browns Valley section as he mentioned. It lies along the purple (Quaternary active) trace mapped by Wesling and Hanson. SC-E means Scarp East Facing. T is Tonal contrast. BIS is Break in slope.
I also put the georeferenced .img file here: https://drive.google.com/file/d/0B2YW8UjIIMEhZnpTR2ZJV1Y1QnM/edit?usp=sharing
So far found evidence for 13 km of surface rupture along azimuth 340, from Green Island Road (near epicenter, due south of Napa airport) north to Brown's Valley area west of Napa. Largest offsets are in north (25cm) and tracking northward is ongoing.
Here is a map of rupture locations south of HWY 12 (toward epicenter). Data collected by Alex Morelan and Chad Trexler. RL offset about 20 cm or less.
I added a KML. Have photos and will post a few.
Kathleen Hodgkinson reports that all BSM stations were online during the event in the Bay Area, San Juan Bautista and Parkfield areas. She has proces high rate BSM data starting 2014-08-23T00:00:00 through 2014-08-24T13:00:00 located at http://borehole.unavco.org/bsm/earthquakes/20140824_NWofAmericanCanyonCalifornia/
“There are large strain offsets on the closest Bay Area strainmeter B054. The strainmeters to the south have good recordings of the dynamic strains but the static strain offsets are small, as you might expect.”
All but three GPS stations within 200km of the event are online (though they are collecting data). A plan for high rate data download is currently underway. If anyone is interested in a custom dataset (1Hz or 5Hz) from PBO GPS sites please submit a request to: http://www.unavco.org/data/data-help/custom-data-request/custom-data-request.html
Regards,
Chris
Shared with by Mark Benthien.
Alex Morelan and Chad Trexler (UCD Ph.D. students) are sending me reports and locations. Fault ruptures are on Browns's Valley segment of the West Napa fault, mapped as Q active in this refrence:
Bryant, W.A., 1982, West Napa fault zone and Soda Creek (East Napa) fault, Napa County: California Division of Mines and Geology Fault Evaluation Report FER-129, microfiche copy in Division of Mines and Geology Open-File Report 90-10, 18 p., scale 1:24,000.
I am assembling a KML of locations and pictures as they come in.
In line with our post-earthquake communications plan, we have published appropriate levels of outreach information on all social media channels (ECA, ShakeOut, and SCEC). Our primary objective has been to inform people of possible aftershocks and risks. Additionally, we are monitoring conversations to help prevent incorrect information from spreading and assess damage from photos/videos that the public and media are uploading.
A noticeable, expected spike in followership, audience attendance, and engagement has been seen on all channels. Many gov, 501(3)c, and businesses are consulting and sharing our information and the public seems to be grasping the content aggressively.
We will be tying this more deeply into our outreach activities and communications tools in the following days as scientific information becomes more available. Please feel free to reach out especially on Twitter: @SCEC, @ECA, and/or @ShakeOut
GPS location 0559049E, 4233942n (utm zone 10)
added an image of the 2 m dem computed from 2003 lidar from NCALM at OpenTopography. Here is link to kmz: https://drive.google.com/file/d/0B2YW8UjIIMEhTDliMXZjekY3dTA/edit?usp=sharing
The rupture across highway 121 is to the west, in the carneros hills area. The westing and Hanson report maps lineaments and low amplitude folding in the napa river flood plain. This connects to a prominent scarp at Alston park in the city of napa, Recently Tim Dawson trenched this west napa fault 'scarp' and found no fault! Scarp must be fluvial there. All in all the fault locations in napa valley are not terribly well known, though there is enough evidence to strongly suggest that an active fault runs up the length of the valley on its west side.
The ca fault activity map does have a carneros fault on it. Perhaps this is the source?
Coincidentally I have a pending NEHRP proposal to work on the west napa fault fault in Northern napa valley near st Helena and Calistoga. It's well expressed in the LIDAR there.
I think we've sorted out the file access issue too. Thanks!
http://earthquake.usgs.gov/research/external/reports/05HQAG0002.pdf
Yes, it does seem like it. I've not paid attention to this before, but perhaps it's just an artifact of the code, and how long it takes to declare an alert and start drawing the circles. Good question for Richard.
Is the yellow circle the P-wave? If so, they're alerting about a second before the P-wave emerges at the epicenter...
FYI: http://www.californiaeqclearinghouse.org/m6-0-south-napa-earthquake/
Just talked to Tom Brocher on the phone. He said:
(1) 5 geologists, including Ben Brooks and Dave Schwartz, are headed up to look for surface rupture.
(2) Tom Holzer is headed up to look for ground failure.
(3) Jess Murray is looking at GPS data and have information on displacements. Her group will be resurveying campaign-GPS sites within the next day or so.
(4) Paul Spudich is coordinating seismic response. Possible targets include the delta, ground-motion effects, and fault-zone imaging.
(5) He has heard from John Parrish that CGS is sending at least 3 geologists.
(6) The state is setting up a clearinghouse, and Tom said that the USGS would post information there. Anne Rosinski is the point of contact for that.
Nice success for Shake Alert with initial magnitude at M5.7. Obviously too close to be of much use in this case, but still a good example of EEW capabilities.
https://www.youtube.com/watch?v=DwdCJ31LFGI&feature=youtu.be
good morning everyone.
I posted a few things earlier on my blog: http://activetectonics.blogspot.com/2014/08/24-august-2014-m6-earthquake...
Nothing that you won't already know but I did make a figure combining the focal mechanism and the active fault traces. I attached the image here. Center of focal mechanism is at epicenter
I saw a nice map of the event and aftershocks at http://seismo.berkeley.edu/index.html
I sorted out the threaded settings, and once I saved settings it worked, so I edited my post...
Still can't get to either of the posted images?
Jamie - Try again? Fixed the file attachment from Greg and you can change your comment viewing settings at top. --Tran
File from Greg does not seem to be available...