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  • wholt
    2014.08.24 - M6.0 South Napa Earthquake, California   14 weeks 5 days ago

     As part of the 'transient detection' effort we are conducting using PBO data we also calculate 1 day solutions. Attached are observed and model strains (contoured dilatation) and also the computed Coulomb Stress change estimates on faults (with seismicity Aug 24 - Sept. 6), determined using the GPS-strains.  The August 24th solution from PBO UNAVCO showed slightly lower offsets than the attached figure. Bill Hammond provided this data set of 24 hour displacements.  The method for computing strain changes is described in Holt and Shcherbenko [2013], SRL.

     

    Bill Holt

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   14 weeks 6 days ago

    We are sharing the following products derived from COSMO-SkyMed in ascending orbit. 

     

    Image:

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/...

     

    Kmz:

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/...

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/...

     

    Data:

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/...

     

    Caption: Interferometric Synthetic Aperture Radar (InSAR) map of coseismic displacement in the radar line-of-sight (LOS, 40 degrees from vertical and roughly east) caused by the 2014/08/24 M6.0 South Napa Earthquake, California. Derived from radar data of COSMO-SkyMed satellite in ascending orbit acquired on 2014/06/19 and 2014/09/03. Processed by ARIA team at JPL-Caltech in collaboration with the Italian Space Agency (ASI) and University of Basilicata. The epicenter indicated with the red star is from USGS NEIC. COSMO-SkyMed data (c) ASI 2014.

     

    Contact aria@jpl.nasa.gov or aria@caltech.edu for more information.

     

    -- Sang-Ho Yun, JPL-Caltech ARIA project

     

  • ccrosby
    2014.08.24 - M6.0 South Napa Earthquake, California   14 weeks 6 days ago

     With assistance from Heezin at NCALM, we've made the original full unfiltered point cloud data from the 2003 NCALM Napa Watershed survey available on OpenTopography. As you likely know the dataset on OT at the moment (http://opentopography.org/id/OTLAS.052010.26910.1) is limited to the filtered last returns. We've added a link to the top of the page that points to our file server (https://cloud.sdsc.edu/v1/AUTH_opentopography/PC_Bulk/Napa/NAPA_ASCII_03/Unfiltered_XYZ/) where you can download the full point cloud as unfiltered ascii xyz. You can pull the dataset from the file server using wget, curl, or a download manager such as DownThemAll.

  • fielding
    2014.08.24 - M6.0 South Napa Earthquake, California   15 weeks 8 hours ago

    Several UAVSAR flight lines acquired on Aug. 29, 2014 over Napa and adjacent areas have been processed with previous flight data to repeat-pass interferometry (RPI) products for coseismic interferograms. The line 23511 covers the main fault rupture and the data, including KMZ versions and the full digital dataset, is available at:

    http://uavsar.jpl.nasa.gov/cgi-bin/product.pl?jobName=SanAnd_23511_14068...

    ++Eric

  • jhardebeck
    2014.08.24 - M6.0 South Napa Earthquake, California   15 weeks 16 hours ago

    Updated aftershock locations, for the first week.  These locations should be better because some velocity model issues have been worked out.

  • lutz
    2014.08.24 - M6.0 South Napa Earthquake, California   15 weeks 5 days ago

    Hello all,

    After this weekend's hot weather I've noticed that the reach of fault rupture between Highway 121 and Middle Avenue is delineated by dying grape vines with leaves that have turned from green to yellow or red. I don't know how common this is, but in the short term this may be helpful for identifying surface rupture in previously unknown areas or across vineyards where access is an issue. I expect this should show up well in any aerial photos that might be taken this week.

    Either the roots have been damaged or the irrigation systems are dripping too far into fissures for the plants to access, or both.

    Here's an example, kmz of photo taken on Middle Avenue between Los Carneros Avenue and Cuttings Wharf Road: 

    https://infraterra.box.com/s/8wgwvp1tejavvf327odn

    -Andy Lutz

  • dawson
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 1 day ago

     Attached are photos taken on Los Carneros road on consecutive days 8/24 and 8/25.  There is a perceptible amount of afterslip, but seems less than at the Highway crossing to the north.  Sorry no scale, I didn't have one at the time.

     

    Tim

  • fielding
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    Ken,

    Great to hear that you and Tim have been able to find field evidence to match the small phase offsets in the COSMO-SkyMed interferogram for Napa, at least at a few locations. Both the COSMO-SkyMed and TerraSAR-X interferograms (which we studied for the 2012 Brawley swarm) are X-band (3.1 cm) radar wavelengths and have very high resolution (roughly 2-3 m original pixel size), so it makes sense that they show features that are smaller than the older satellites with longer radar wavelengths (6 or 24 cm) and larger pixels (10-20 m).

    UAVSAR data was acquired earlier today, repeating lines mostly imaged in May 2014, and we hope that they can process at least some of the InSAR data by the end of next week.

    ++Eric

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From Tom Brocher (USGS) 8/29/14 1:33pm PDT:

    Site NP.1759 is just north of downtown Vallejo. It recorded a PGA on 35% g (on E-W component). Location: 38.107700, -122.256199, at an epicentral distance of 13.5 km.


    ---------- Forwarded message ----------
    From: Luetgert, James
    Date: Fri, Aug 29, 2014 at 12:50 PM
    Subject: 1759

    This just in:
    SCNL: 1759.HNE.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 338.935333 TPGA: 2014/08/24 10:20:51.655 METH: MS
    PGV: 17.074072 TPGV: 2014/08/24 10:20:51.565 METH: IT 5.9
    PGD: 2.872506 TPGD: 2014/08/24 10:20:51.650 METH: IT 5.9
    SA: 0.3 683.735168 TSA: 2014/08/24 10:20:51.710 METH: NJ
    SA: 1.0 184.433228 TSA: 2014/08/24 10:20:52.445 METH: NJ
    SA: 3.0 16.065966 TSA: 2014/08/24 10:20:51.615 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000
    SCNL: 1759.HNN.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 125.104507 TPGA: 2014/08/24 10:20:51.500 METH: MS
    PGV: 8.902310 TPGV: 2014/08/24 10:20:51.780 METH: IT 5.9
    PGD: 0.808297 TPGD: 2014/08/24 10:20:51.915 METH: IT 5.9
    SA: 0.3 331.781738 TSA: 2014/08/24 10:20:51.700 METH: NJ
    SA: 1.0 44.211834 TSA: 2014/08/24 10:20:59.790 METH: NJ
    SA: 3.0 8.486643 TSA: 2014/08/24 10:21:20.765 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000
    SCNL: 1759.HNZ.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 55.815113 TPGA: 2014/08/24 10:20:50.195 METH: MS
    PGV: 3.158833 TPGV: 2014/08/24 10:20:52.610 METH: IT 5.9
    PGD: 0.443734 TPGD: 2014/08/24 10:20:58.290 METH: IT 5.9
    SA: 0.3 111.896385 TSA: 2014/08/24 10:20:52.705 METH: NJ
    SA: 1.0 30.572836 TSA: 2014/08/24 10:20:54.035 METH: NJ
    SA: 3.0 7.167205 TSA: 2014/08/24 10:21:30.555 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000
    Site NP.1759 is just north of downtown Vallejo. It recorded a PGA on 35% g (on E-W component). Location: 38.107700, -122.256199, at an epicentral distance of 13.5 km.
    Tom Brocher
    Director, Earthquake Science Center, USGS
    345 Middlefield Road, MS 977
    Menlo Park, CA 94025
    Work: 650-329-4737
    Cell: 650-644-5927
    Fax: 650-329-5617


    ---------- Forwarded message ----------
    From: Luetgert, James <luetgert@usgs.gov>
    Date: Fri, Aug 29, 2014 at 12:50 PM
    Subject: 1759
    To: Thomas Brocher <brocher@usgs.gov>


    This just in:
    SCNL: 1759.HNE.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 338.935333 TPGA: 2014/08/24 10:20:51.655 METH: MS
    PGV: 17.074072 TPGV: 2014/08/24 10:20:51.565 METH: IT 5.9
    PGD: 2.872506 TPGD: 2014/08/24 10:20:51.650 METH: IT 5.9
    SA: 0.3 683.735168 TSA: 2014/08/24 10:20:51.710 METH: NJ
    SA: 1.0 184.433228 TSA: 2014/08/24 10:20:52.445 METH: NJ
    SA: 3.0 16.065966 TSA: 2014/08/24 10:20:51.615 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000
    SCNL: 1759.HNN.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 125.104507 TPGA: 2014/08/24 10:20:51.500 METH: MS
    PGV: 8.902310 TPGV: 2014/08/24 10:20:51.780 METH: IT 5.9
    PGD: 0.808297 TPGD: 2014/08/24 10:20:51.915 METH: IT 5.9
    SA: 0.3 331.781738 TSA: 2014/08/24 10:20:51.700 METH: NJ
    SA: 1.0 44.211834 TSA: 2014/08/24 10:20:59.790 METH: NJ
    SA: 3.0 8.486643 TSA: 2014/08/24 10:21:20.765 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000
    SCNL: 1759.HNZ.NP.--
    WINDOW: 2014/08/24 10:20:47.500 LENGTH: 74.000
    PGA: 55.815113 TPGA: 2014/08/24 10:20:50.195 METH: MS
    PGV: 3.158833 TPGV: 2014/08/24 10:20:52.610 METH: IT 5.9
    PGD: 0.443734 TPGD: 2014/08/24 10:20:58.290 METH: IT 5.9
    SA: 0.3 111.896385 TSA: 2014/08/24 10:20:52.705 METH: NJ
    SA: 1.0 30.572836 TSA: 2014/08/24 10:20:54.035 METH: NJ
    SA: 3.0 7.167205 TSA: 2014/08/24 10:21:30.555 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 19:44:57.000

     

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From David Oppenheimer (USGS) 8/29/14 1:08pm PDT:

    Mainshock peak ground motion waveforms from the last 4 free-field stations has been recovered and incorporated into ShakeMap. This is likely to be the final ShakeMap.
    NC.NMI - Mare Island (37% PGA, 19cm/s)
    NC.NSP - Sears Point (5% PGA, 8cm/s)
    NC.NBRB - Beebe Ranch (~5 km west of Petaluma) (4%PGA, 10cm/s)
    NC.CRPB - Russelman Park (north flank of Mt Diablo)

    Chris Stephens is processing the records and will post them to the CESMD ASAP.

    Thanks to NCSN and NSMP field crews for recovering all of these records, Jim Luetgert for shepherding them through the system, and Pete Lombard for regenerating the ShakeMaps.

    -David

     

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From Andreas Llenos (USGS) 10/29/14 12:05pm PDT:


    Something else that may be of interest - a comparison of the South Napa and Parkfield magnitude-frequency distributions, for the first ~5.5 days of each sequence). The crosses in the figure are the incremental counts in each magnitude bin, and the dots are the cumulative counts. Estimated b-values and completeness magnitudes (from Aki's MLE method) are in the title.

    Andy has helpfully suggested a few other M~6 sequences to look at (Morgan Hill and Palm Springs), so I'll try to make similar comparisons with those too.

    Andrea


    ---------- Forwarded message ----------
    From: Llenos, Andrea
    Date: Fri, Aug 29, 2014 at 9:22 AM


    Hi Keith,

    As a quick comparison with Parkfield, in the same ~4.5 days after the mainshock, Parkfield had 7 M>=4 aftershocks, 2 of which were M~5, and there were a total of around 226 M>=1.8 aftershocks (compared to the 59 M>=1.8 aftershocks Napa has had so far).

    Andrea


    On Fri, Aug 29, 2014 at 8:39 AM, Knudsen, Keith  wrote:

    Hi Andrea
    I'm wondering how rare is it to have a M6 earthquake without any magnitude 4 or 5 aftershocks 9at least so far...). The South Napa earthquake seems to have had an unproductive aftershock sequence. Any thoughts?
    Keith

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From Brad Aagaard (USGS) 8/29/14 10:58 am PDT:

    Hi all,

    I just posted the following document on the USGS Eq Response Google Drive. Attached here for broader distribution.

    Brad

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From Tom Brocher (USGS) 8/29/14 10:37am PDT:

    In addition to the Mare Island recording, we are working on processing two other retrieved records, both west of the epicenter:

    North of Sears Point (NSP): PGA ~5% g, 38.200200, -122.464399, epicentral distance of 13.5 km.

    NBRB (east of Napa near Rodgers Creek Fault): PGA ~4% g, 38.260200, -122.551800, epicentral distance of 21.4 km.

    Jim Luetgert's email below provides more details.

    Tom


    ---------- Forwarded message ----------
    From: Luetgert, James
    Date: Fri, Aug 29, 2014 at 10:13 AM
    Subject: Mare Island, Sears Point, NBRB


    Hi Tom,

    Here are the numbers.

    NMI - PGAmax ~37%g
    NSP - PGAmax ~5%g
    NBRB - PGAmax ~4%g

    SCNL: NMI.0.--.
    WINDOW: 2014/08/24 10:20:48.200 LENGTH: 123.000
    PGA: 178.695023 TPGA: 2014/08/24 10:20:52.910 METH: MS
    PGV: 7.344642 TPGV: 2014/08/24 10:20:52.870 METH: IT 5.9
    PGD: 1.294780 TPGD: 2014/08/24 10:20:52.780 METH: IT 5.9
    SA: 0.3 492.547546 TSA: 2014/08/24 10:20:54.050 METH: NJ
    SA: 1.0 94.245888 TSA: 2014/08/24 10:20:53.660 METH: NJ
    SA: 3.0 10.506660 TSA: 2014/08/24 10:21:29.390 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/28 17:05:56.000


    SCNL: NMI.1.--.
    WINDOW: 2014/08/24 10:20:48.200 LENGTH: 123.000
    PGA: 370.258698 TPGA: 2014/08/24 10:20:52.850 METH: MS
    PGV: 19.024614 TPGV: 2014/08/24 10:20:52.770 METH: IT 5.9
    PGD: 1.191846 TPGD: 2014/08/24 10:20:56.680 METH: IT 5.9
    SA: 0.3 893.040222 TSA: 2014/08/24 10:20:52.900 METH: NJ
    SA: 1.0 73.242455 TSA: 2014/08/24 10:20:53.980 METH: NJ
    SA: 3.0 16.645491 TSA: 2014/08/24 10:21:24.370 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/28 17:05:56.000


    SCNL: NMI.2.--.
    WINDOW: 2014/08/24 10:20:48.200 LENGTH: 123.000
    PGA: 75.739395 TPGA: 2014/08/24 10:20:53.030 METH: MS
    PGV: 3.798816 TPGV: 2014/08/24 10:20:52.700 METH: IT 5.9
    PGD: 0.410264 TPGD: 2014/08/24 10:21:05.770 METH: IT 5.9
    SA: 0.3 163.326202 TSA: 2014/08/24 10:20:53.200 METH: NJ
    SA: 1.0 25.422508 TSA: 2014/08/24 10:21:07.980 METH: NJ
    SA: 3.0 4.106350 TSA: 2014/08/24 10:21:44.450 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/28 17:05:56.000

    **************************************

     

    SCNL: NSP.0.--.
    WINDOW: 2014/08/24 10:20:49.200 LENGTH: 117.000
    PGA: 40.219242 TPGA: 2014/08/24 10:20:52.000 METH: MS
    PGV: 7.779984 TPGV: 2014/08/24 10:20:59.050 METH: IT 5.9
    PGD: 3.254269 TPGD: 2014/08/24 10:20:58.420 METH: IT 5.9
    SA: 0.3 139.697739 TSA: 2014/08/24 10:20:52.820 METH: NJ
    SA: 1.0 48.749874 TSA: 2014/08/24 10:20:58.460 METH: NJ
    SA: 3.0 18.211746 TSA: 2014/08/24 10:21:00.410 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:06:16.000

    SCNL: NSP.1.--.
    WINDOW: 2014/08/24 10:20:49.200 LENGTH: 117.000
    PGA: 53.492172 TPGA: 2014/08/24 10:20:51.460 METH: MS
    PGV: 6.885780 TPGV: 2014/08/24 10:20:52.460 METH: IT 5.9
    PGD: 2.882841 TPGD: 2014/08/24 10:20:53.030 METH: IT 5.9
    SA: 0.3 102.869164 TSA: 2014/08/24 10:20:56.660 METH: NJ
    SA: 1.0 68.953758 TSA: 2014/08/24 10:20:51.670 METH: NJ
    SA: 3.0 29.321514 TSA: 2014/08/24 10:20:56.590 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:06:16.000

    SCNL: NSP.2.--.
    WINDOW: 2014/08/24 10:20:49.200 LENGTH: 117.000
    PGA: 25.852768 TPGA: 2014/08/24 10:20:53.630 METH: MS
    PGV: 2.356088 TPGV: 2014/08/24 10:20:55.560 METH: IT 5.9
    PGD: 0.724186 TPGD: 2014/08/24 10:20:54.780 METH: IT 5.9
    SA: 0.3 43.953094 TSA: 2014/08/24 10:20:55.920 METH: NJ
    SA: 1.0 31.836840 TSA: 2014/08/24 10:20:54.060 METH: NJ
    SA: 3.0 8.032551 TSA: 2014/08/24 10:21:06.180 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:06:16.000


    **************************************


    SCNL: NBRB.0.--.
    WINDOW: 2014/08/24 10:20:52.700 LENGTH: 137.000
    PGA: 37.169041 TPGA: 2014/08/24 10:20:58.660 METH: MS
    PGV: 7.565430 TPGV: 2014/08/24 10:21:03.550 METH: IT 5.9
    PGD: 3.600266 TPGD: 2014/08/24 10:21:04.030 METH: IT 5.9
    SA: 0.3 79.279381 TSA: 2014/08/24 10:20:56.810 METH: NJ
    SA: 1.0 65.979889 TSA: 2014/08/24 10:21:04.040 METH: NJ
    SA: 3.0 32.776333 TSA: 2014/08/24 10:21:06.110 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:05:42.000

    SCNL: NBRB.1.--.
    WINDOW: 2014/08/24 10:20:52.700 LENGTH: 137.000
    PGA: 43.000057 TPGA: 2014/08/24 10:20:53.950 METH: MS
    PGV: 10.631454 TPGV: 2014/08/24 10:21:01.870 METH: IT 5.9
    PGD: 6.431492 TPGD: 2014/08/24 10:21:01.270 METH: IT 5.9
    SA: 0.3 122.470329 TSA: 2014/08/24 10:20:54.020 METH: NJ
    SA: 1.0 66.995247 TSA: 2014/08/24 10:21:01.270 METH: NJ
    SA: 3.0 70.444214 TSA: 2014/08/24 10:21:03.480 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:05:42.000

    SCNL: NBRB.2.--.
    WINDOW: 2014/08/24 10:20:52.700 LENGTH: 137.000
    PGA: 28.903296 TPGA: 2014/08/24 10:20:58.750 METH: MS
    PGV: 6.264317 TPGV: 2014/08/24 10:20:58.060 METH: IT 5.9
    PGD: 2.378298 TPGD: 2014/08/24 10:21:02.340 METH: IT 5.9
    SA: 0.3 72.377060 TSA: 2014/08/24 10:20:54.370 METH: NJ
    SA: 1.0 51.562531 TSA: 2014/08/24 10:20:57.680 METH: NJ
    SA: 3.0 36.036144 TSA: 2014/08/24 10:21:09.020 METH: NJ
    EVID: - -
    AUTH: NC 2014/08/29 17:05:42.000

    Cheers, -Jim

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    From Tom Brocher (USGS) 8/29 10:21am PDT:

    I'm forwarding a note from Chris Stephens about the USGS recording from Mare Island (NMI) which recorded a PGA of about 37% g.

    The coordinates for this station, on the southern end of Mare Island, are 38.07600 deg North and -122.25850 deg East. The epicentral is 16.7 km.

    Chris is working to get the record into the CESMD site.

    Tom


    ---------- Forwarded message ----------
    From: Stephens, Christopher
    Date: Fri, Aug 29, 2014 at 10:10 AM
    Subject: Preliminary processing for NC.NMI


    Tom-

    Dave asked me to send you the preliminary PGA values for this site.
    Please see attached. The PGA on the N-S component is ~0.37 g.

    The record requires some additional processing to address some baseline correction
    issues. The influence of this can be seen in the displacement, but it will not significantly
    affect the acceleration or velocity records.

    Chris

  • dawson
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

     Below is a link to my dropbox where I have dumped my various kmz files with photos and (disclaimer) unedited notes.  Free feel to take a look, if you use it for anything, please let me know and provide acknowledgement.  If you have questions, feel free to ask, but be aware, it may be a while until I can get back to you, at least until things settle down.

    Cheers,

    Tim

     timothy.dawson@conservation.ca.gov

    https://www.dropbox.com/sh/lsmhjsj6egjuirc/AACqVpYtmWCiEL5gs9P9jhmda?dl=0

     

     

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    I agree with the consensus that the minor cracking along the scarp at Alston Park is shaking-induced. 

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 2 days ago

    Thank you for following up on this. We also visited the site yesterday and agree that these features are non-tectonic.  

  • hudnut
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

    After receiving the InSAR results as a high-resolution KMZ file from Sang-Ho Yun (JPL), Tim Dawson (CGS) and I first checked at the Napa County Airport yesterday (Wed.) afternoon, and we did find one runway with clearly tectonic fractures but no measurable displacement (see photos attached).

    After that, Tim went south and I went north to perform additional checks. Essentially, neither of us found anything else as good as the airport site yesterday.

    In all, I took 208 photos on Wed.-Thurs. but attached here are just a couple of samples. I loaded the InSAR KMZ onto my laptop in Google Earth, then plugged my Garmin into the laptop and did real-time navigation and used that to locate myself on the InSAR results as I drove around.

    Today, I continued searching and also went to a list of other sites that needed to be checked. Some turned out to be duplicated efforts with what Ron Rubin (CGS) has already reported this evening, at the Alston Park and Dry Creek driveway sites. Not bad to have multiple assessments.

    My GPS track is attached here in KML formats (GPX upload is not allowed so e-mail me if you prefer the GPX file) so that others can see the localities that I have checked. Mostly, these are from tracking down features that looked interesting in the InSAR.

    In any case, overall these checks did not turn out to reveal any additional significant slip on newly recognized strands. I think the InSAR is sensitive to small (<1-2 cm) slip that is absorbed by shear in shallow soils. We saw this, too, for the Brawley Swarm.

    Carol Prentice and colleagues from USGS Menlo Park found, on Tues., several additional strands that lie farther east than had been recognized on Sun.-Mon. and these were included in the v.6 AOI for the LiDAR acquisition plan.

    Alex Morelan led us to the site at 3051 Redwood Creek Road that does have tectonic slip of ~10 mm (see photos attached). These breaks take off at N25W through the vineyard, but we did not follow them today. Maybe someone else will get a chance to do so - that would be good.

    On the basis of these newly identified and confirmed 'definitive' displacement of tectonic origin (found on Tues., Wed. and Thurs.), I revised the polygon for the LiDAR and finalized it this afternoon, with the help of the cost-share partner group via e-mail and phone calls (see earlier note).

    Tomorrow morning, I will check the strand that Carol Prentice and colleagues found and work southwards along it to see if it warrants LiDAR coverage (it is not all included in v.6 and has not yet been field-checked to my knowledge).

    Thanks for your interest, feel free to ask questions here or else via e-mail to hudnut@usgs.gov or call or text me at 626-672-6295. I'll be in the field through next Tues., perhaps longer, from now on working more with Ben Brooks on laser scanning.

         Ken

  • ronrubin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

     I probably should have posted this earlier but Gordon and I were able to visit these locations and several others in the Dry Creek road area yesterday.  We also met with Nick.  I think we were able to eliminate the features as non-tectonic.  Most of the cracks appear to be pre-existing, and have been enhanced by shaking.  None of the cracks in paved areas have lateral displacements, nor do they extend into the soil.  The cracks at 4155 are clearly related to gravitational movement on the very steep driveway.  

  • ronrubin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

     The cracking noted early on at Alston Park has been looked at by Tim and I, as well as several others who are mapping the rupture to the east. The consensus is they are non-tectonic cracks that have been enhanced by shaking. The orientation of the longer crack is not favorable, and the other appeared to be one of many pre-existing irregular cracks in clayey soil. No cracks were observed in the area of our trench, and no other evidence of tectonic rupture has been observed nearby. 

    It is also worth pointing out that in contrast to the commentary in the original post here, the lack of tectonic deformation is consistent with the results of our trench across the slope. It was over 3 m deep and exposed Pleistocene and possibly older sediments, un-faulted. We held a trench review and the consensus concurred with that conclusion.

  • bbrooks
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

     Since early hours after the event a USGS team including Steve DeLong, Ken Hudnut, Nikita Avdievitch, Ali Pickering, and myself with remote participation from Kate Scharer (USGS Pasadena) and Craig Glennie (NCALM/U Houston) have collected multiple, complimentary near-field imaging data sets. We've collected mobile laser scans (MLS, truck- and back-pack mounted), terrestrial laser scans, and helicopter photography for structure from motion (SFM) application (referred to in earlier posting by Kate Scharer). 

    - Two of the tracks from the MLS scans are attached here. The file name has collection date (_yymmdd).
    We were able to collect data before road repair in most places. Two other backpack scans were carried out: one at the ~500m rupture exposure on the Atlas vineyard off Buhmann road (the zone of high slip just to the south of Oak Rock lane) the other in the vineyard just north of the Hwy12/Cutting Wharf intersection. 

    - TLS scanning has focused south of Hwy12/Cutting Wharf intersection.

    - Photos from the helicopter were regional.

    We've just returned from the field, so processing of data has just begun, hopefully more to show soon...

     

  • gareth
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

    I have taken the Cosmo-Skymed interferogram that Sang-Ho Yun and the ARIA project have kindly provided, and uploaded it to the 'Visible Earthquakes' tool. This is an interactive InSAR modeling website that I have been developing along with Rowan Cockett of 3 point Science, with financial support provided by UNAVCO:

    The site is here: http://www.3ptscience.com/earthquake

    The Visible Earthquakes tool allows you to make a simple uniform-slip model of an earthquake, by allowing you to manually adjust individual fault parameters within the web interface, and to see how that changes a model interferogram. By comparing this model side-by-side with the real data, you can fine-tune it until you reach an acceptable match. If you are happy with the model, you can submit it, and we can collect statistics on the results. 

    The tool is still in beta testing, and has only limited supporting documentation, but the controls are easy to learn and use, so please try it out. Setting up an account (which is required to access the modeling functions), means that we can keep track of your models. Hopefully even non-InSAR specialists can have a go at modeling the earthquake!

  • fielding
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

    The NASA-JPL UAVSAR system is planning a flight over the area tomorrow (Friday) August 29 to image the sites
    potentially impacted by the Napa Earthquake.

    Flight plan:
    http://uavsar.jpl.nasa.gov/cgi-bin/report.pl?planID=PLAN_743_v01#flightPlan
     

     

  • hudnut
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

    The attached figure shows the flight lines from the inital aerial photography done on Monday (8/25/2014) morning by USGS and CHP in light blue.

    The planned airborne LiDAR acquisition polygon (v.6) is overlain as a white line bounded area that covers all faults that broke with significant and clearly tectonic rupture that have been identified at this time. This additional imagery will be acquired soon, hopefully within the next few days (pending funding arrangements). This is being cost-shared by a coalition of federal and state agencies including CGS, USGS, PEER/GEER, DWR and potentially others.

    Please feel free to ask questions about all of this. I've been busy with field work, racing to get things done before the pavement grinders destroy evidence.

    Thanks for your interest and support!

         - Ken

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   16 weeks 3 days ago

    From Tom Brocher (USGS) 8/28/14 1:07pm:

    Ross Stein's interpretation of the Coulomb stress with respect to the aftershocks. According to Ross's interpretation, there have been two small earthquakes on the Green Valley Fault triggered by these changes.

    Tom
    ---------- Forwarded message ----------
    From: Stein, Ross <rstein@usgs.gov>
    Date: Thu, Aug 28, 2014 at 1:00 PM
    Subject: Updated and interpreted Coulomb stress on surrounding UCERF3 faults


    People,

    Tom Brocher asked me for an updated Coulomb assessment and statement. Although I would prefer to get everyone's concurrence on the interpretation, in the interest of time here it is, and we can revise it in due course.

    Of particular note are the two shocks that struck on or near the Green Valley fault today; there have been no such shocks during the past several weeks, so these I interpret as a possible rate gain on a stressed fault section.

    My thanks to Shinji for wrestling the UCERF3 fault file into submission with help from Kevin Milner.

    Best,

    R o s s