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  • dreger
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    I have updated the preliminary UCB finite-source slip model. The rupture extends approximately 12 km N-NW of the epicenter and updip from 11 km to 2 km depth. There is shallower slip in the model that is not as well resolved. The location of the shallowest slip is consistent with the reported  locations of peak surface offsets. The kinematics of the rupture process would produce a strong directivity effect in Napa, CA.

  • barnhartwd
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     We've derived a fault slip model from regional GPS. Slip distribution and location map/information are attached below. Please email wbarnhart@usgs.gov to request further details on the fault source model. We will continue to update on this forum as the GPS positions improve.

     

  • arrowsmi
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     I ran the kmz Mike Oskin posted last night through my GlobalMapper and exported it as attached txt file. Might need a bit of cleanup for your purposes.

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     Locations in kmz are in utm meters and accurate to a few meters. 

  • ccrosby
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    There is coverage of the epicentral region in the 2003 Napa Watershed lidar dataset collected by NCALM, available from OpenTopography here:  http://opentopography.org/id/OTLAS.052010.26910.1

    There is also a 2010 San Francisco Bay lidar dataset available from NOAA that appears to cover the EQ extent: http://www.csc.noaa.gov/dataviewer/index.html?action=advsearch&qType=in&qFld=ID&qVal=584#

    -cc

  • ybock
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    The READI group has been analyzing 1 Hz GPS data collected in real time from stations within 75 km of the epicenter. At SOPAC we have produced 1 Hz displacements using PPP-AR analysis (Geng et al., G-cubed, 2013). Attached is a slide with 1 Hz displacements from 6 stations. The complete set of plots and displacements will be posted on GPS Explorer (http://geoapp03.ucsd.edu/gridsphere/gridsphere?cid=Earthquakes) later this afternoon, or contact jgeng@ucsd.edu for a tar file. We've heard from UNAVCO that they are downloading 5 Hz GPS data from PBO stations within 300 km of the epicenter.

    Attached is a list of stations and the slide.

  • dreger
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    If possible could you post a ascii file with lat,lon, slip for all surveyed points? I would like to use your observations as a constraint in a finite-source inversion. I can get some of it from the figure and kmz, but it would be better if I had all of the observations.

     

    Best

    Doug

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    From Doug Dreger (UC Berkeley) 8/25 11:25am:

    This is a preliminary finite-source model. It uses BDM, BKS, HOPS, CVS, MNRC, MCCM, FARB, and JRSC. The model is unilateral to the NW and updip. I used the UCB TDMT focal mechanism (155,82,-172). Single time window, rise time 0.6 seconds. Data and GFs were filtered between 0.02 to 1 Hz.

    I am working on filling in the Green's function data base that was used, and will then better explore the moment minimization and smoothing constraints, and will send you an update.

    Jack, how does this compare with your results?

    I have asked Ingrid for static GPS, which I can incorporate, and will send her a follow up email in a minute.

    Best
    Doug

  • huynht
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago
  • huynht
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    An EERI Virtual Clearinghouse has been established at: http://www.eqclearinghouse.org/2014-08-24-south-napa/. It has interactive ArcGIS data map.

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     Alex and Chad found a lot of N to NE striking strands at the northern rupture termination. The LL offset is clear in the pavement but rotation of slabs of pavement could cause that. In any case the zone if rupture is quite wide in brown's valley.

  • Treiman
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago
    If the left-lateral offset you mention is that noted at "Redwood Rd 2" I wonder if that wasn't just an artifact of rotation of the pavement slabs? I note in the photo that it looks like a nice left-step in the fractures that cross the road, suggestive of right-lateral shear.
  • jrmurray
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     Field personnel from USGS Menlo Park began deploying instruments yesterday (8/24) at sites in the epicentral region where we have pre-earthquake data.  USGS and UCR/MIT are coordinating on the field response.  The attached map shows target locations for campaign measurements.

  • gareth
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    Serendipitously, Mike Floyd and I are in the region on a GPS campaign and have diverted to the Napa area. We have 5 receivers each (i.e. 10 in total) and are planning to deploy them all at sites around Napa this afternoon.

    More when I have better internet.

    Update 15.15 PDT

    Our target sites are the following (see attached kmz):

    SPRR -122.1863 38.2086
    AMER -122.1992 38.1686
    6908 -122.1144 38.1569
    04KH -122.2535 38.1548
    SKAG -122.3806 38.1588
    04KF -122.4677 38.2452
    04LF -122.4786 38.3025
    04LG -122.2994 38.2711
    TRAN -122.3091 38.321
    HAGG -122.2592 38.3239 

    All bar one site (HAGG) were measured by us six weeks ago, so will have good pre-event coordinates. We intend to leave these sites out for the next few days to capture any early postseismic transient deformation.

    Update 21.00 PDT

    All of the above sites were occupied as planned, before 16.30 on Sunday afternoon, by our team (me, Mike Floyd and grad student Jerlyn Swiatlowski). Mike, in addition, occupied one more in the evening using additional equipment supplied by UC Berkeley:

    X552 122.28723W 38.10720N

    There are several more of our campaign sites in the area that could be usefully surveyed, particularly at the north end of the rupture, along highway 29 and parallel roads. If there are any other GPS receivers that can be loaned to the effort, please let us know!

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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.

  • arrowsmi
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    cool to see the rupture zone! 

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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. 

  • arrowsmi
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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.

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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.

  • walls
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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

  • huynht
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    Shared with by Mark Benthien.

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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.

  • jballmann
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

    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

     

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   2 years 34 weeks ago

     GPS location 0559049E, 4233942n (utm zone 10)