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  • ronrubin
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks 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   5 years 25 weeks 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   5 years 25 weeks 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   5 years 25 weeks 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   5 years 25 weeks 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   5 years 25 weeks 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   5 years 25 weeks 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

  • eqadmin
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    From Mike Oskin (UC Davis) 8/28/14 3:28pm PDT:

    Just came back from visiting the rupture. I think the rupture length we originally proposed (16km) still holds. The max slip known is up to 46 cm. Slip maxima is northern half of rupture. Afterslip is largest in the southern half of rupture. Shaking was much stronger in the north (sufficient to buckle sidewalks!), where directivity both along strike up dip focussed energy. No rupture found further north along Dry Creek road. More than one set of air photos have been acquired but have not been fully released. There is a consortium working on funding an airborne lidar survey (EERI, USGS, CGS, and perhaps CalTrans). Offset features are already disappearing with road repair, especially in the city of Napa / Brown’s Valley area.  -Mike

     

  • angelyn
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    We are seeing suggestions of northward postseismic motion at GPS station P200 (38.2398, -122.4517) in both our daily and 30 minute postition estimate timeseries.

    The post-EQ data for day zero is the portion of day 236 after the earthquake.

    Error bars on the daily series are formal errors.  Error bars on the subdaily series are the 3D RMS divided by 3 (which should be an overestimate in the horizontal).  Separate linear fits to the pre-EQ and post-EQ points numerically support a flatter slope before than after.

    We do not see any corresponding north signal at nearby P199.

    Best regards,

    Angie Moore, Sue Owen, Zhen Liu

  • dshelly
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Hi all,

    This may be somewhat peripheral, but in case anyone is interested, it appears that this earthquake triggered some tremor (low frequency earthquakes, LFEs) along the San Andreas near Parkfield.   There was a small sequence mostly just north of Parkfield (-20 to -15 along-strike position on the attached plot) that started within minutes of the waves passing.  A much larger sequence that started ~10 hours later near Cholame (15-40 km along-strike position) may also have been triggered, as there was a bit of activity in this zone earlier, and these episodes are relatively rare (every few months).  These observations are not too surprising given the history of triggered activity in this zone (including apparent triggering by the 2007 M 5.4 Alum Rock earthquake), though the possibility of delayed triggering of a major tremor episode is interesting.

    More notes on the plot:  Along strike position goes from NW (top, -85 km) to SE (bottom, 65 km) - zero position is the town of Parkfield.  Color represents the estimated depth of the LFE family.  For more details see Shelly and Hardebeck, GRL, 2010 or Shelly et al., Nature Geoscience, 2011. 

    Best,

    David

  • scharer
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

     USGS group has been working on rapid acquisition and processing of aerial photos (here from CHP helicopter) for structure from motion digital terrain maps.  Examples attached.

  • herring
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

     Attached are co-seismic offsets from the PBO combined GPS analysis (Central Washington and New Mexico Tech) which used 2-days before the earthquake and 2 days after the earthquake and an updated MIT analysis which uses the same 2-day pairs plus the day of the earthquake split around the time of the earthquake.  Time series plots do not show large post-seismic motions compared the error bars on the daily position estimates.

    The attached PDF plot shows the results with the Green vectors being the JPL ARIA project results, red vectors PBO combined results and black vectors MIT results.  MIT results have error bars based on the RMS scatter of the phase residuals from each sites and the PBO results have a blend of this error model with a site independent  constant error model. 

    Tom Herring

  • baagaard
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    USGS is deploying additional instruments to densify the instrumentation in the Napa Valley. The temporary instruments are mostly Reftek 130s with Trillium Compact and Episensor sensors. A few are Netquakes (GeoSig).

    USGS deployed several instruments on Monday, densifying an existing east-west line running through downtown Napa. Most stations were deployed west of downtown near Browns Valley Rd. Station spacing is 1-2 km. None of these went in with telemetry, but we will be adding telemetry on Thursday.

    On Wednesday-Friday we are deploying 6 stations in the downtown area (one triangular array with ~250m spacing and one with ~800m spacing). We are also deploying an  8 km linear array along Jefferson St with about 1 km spacing. We expect these to all have telemetry.

    Rufus Catchings will be deploying three fault zone arrays using Texans to try and characterize the fault zone. One in the south in the vicinity of Cuttings Wharf along Bayview Ave - Las Amigas - Stanly; one in the north along and off of Redwood and Dry Creek roads, and one in Contra Costa county (to look for continuity of the fault zone across San Pablo Bay).

    Attached is a KMZ file with target locations (and installed locations from Mon).

  • hudnut
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Thanks, Mike. I'll have a look today. It sounds as if David Schwartz checked it on Sunday but that with the possibility of afterslip, it would be worth checking again.

    I have compiled a list of sites that I plan to check today as we try to work towards completeness, partly in order to fine-tune the area-of-interest for the airborne LiDAR.

         Ken

  • hudnut
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Mike,

    Tim & I checked it yesterday; see my reply to Sang-Ho's post.

         Ken

  • hudnut
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Thank you, Sang-Ho, it was helfpul. Yesterday, Tim Dawson (CGS) and I met at Napa County Airport to check the break from your InSAR for possible surface rupture.

    At the airport, we did find en echelon fractures of tectonic origin at one place. We then split up, with Tim checking south and me checking north from there along the tear in phase in the interferogram.

    Neither of us found other localities along that lineament with clear tectonic slip.

    On the basis of this new evidence, I am working on revising the area-of-interest polygon for use in the airborne LiDAR acquisition planning.

    Thank you for the timely InSAR results. It was very helpful.

    Regards,

         Ken

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Please find the COSMOS-SkyMed unwrapped coseismic interferogram data in the following link. Once the zip file is uncompressed, the README file has more details.

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

    Hope this will be helpful for response and research.

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

  • aemorelan
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Below is the link to a KMZ of surface rupture locations documented by the UC Davis team (myself and Chad Trexler). One CSV file contains the locations of each photo as well as a look direction. Another CSV contains a summary of the observations we made. The KMZ contains the sites that we visited, the data collected at each site, and a link to the rest of the pictures associated with the site.

     https://ucdavis.box.com/s/9zsz84638fp90grhikzx

    - Alex Morelan

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    The links below lead you to unwrapped coseismic interferogram that shows the amount of displacement in the radar line-of-sight (see the colorbar on the top). This map gives you information on the extent and the size of the ground deformation. 

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/ARIA_NapaEQ_CSK_D74_coseis_unw.kmz

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/interferogram/ARIA_NapaEQ_CSK_D74_coseis_unw.jpg

    Caption: Interferometric Synthetic Aperture Radar (InSAR) map of coseismic displacement in the radar line-of-sight (LOS, 29 degrees from vertical and roughly west) caused by the 2014/08/24 M6.0 South Napa Earthquake, California. Derived from COSMO-SkyMed data acquired on 2014/07/26 and 2014/08/27. 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. The blue line indicates the North Bay Aqueduct. 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

  • barnhartwd
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    The NEIC has updated the event page on the USGS website to include recent slip distributions (one seismic from Doug Dreger, one geodetic from Bill Barnhart). 

     

    http://earthquake.usgs.gov/earthquakes/eventpage/nc72282711#scientific_f...

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    I am posting a damage proxy map of the affected areas. This zoomable map can help identifying areas to check for potential damage in person on the ground, with drones, or other airborne/spaceborne optical sensors.  

    http://aria-share.jpl.nasa.gov/events/20140824-south_napa/dpm/ARIA_CSK_DPMs_th0.02.kmz 

    Caption: Damage Proxy Map of the the 2014/08/24 M6.0 South Napa Earthquake, California. The red pixels represent areas of potential damage on the ground surface or buildings. There are two frames processed separately, and each frame boundary is indicated with red rectangle. Derived from COSMO-SkyMed data acquired on 2014/06/08, 2014/07/26, and 2014/08/27. Processed by ARIA team at JPL-Caltech in collaboration with the Italian Space Agency (ASI) and University of Basilicata. 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

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    I am posting this again, as I cannot find the "edit" button I used to see. The COSMO-SkyMed coseismic interferogram URL has changed. The new URL is as follows. The zoomable wrapped interferogram can help locating surface ruptures. For example, there could to be one about 2.5 km east from the epicenter, running parallel to what Mike Oskin mapped. 

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

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

    Caption: Interferometric Synthetic Aperture Radar (InSAR) map of coseismic displacement (wrapped interferogram) in the radar line-of-sight (LOS, 29 degrees from vertical and roughly west) caused by the 2014/08/24 M6.0 South Napa Earthquake, California. Derived from COSMO-SkyMed data acquired on 2014/07/26 and 2014/08/27. One color cycle represents 1.56 cm of LOS displacement. 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. The white line indicates the North Bay Aqueduct. 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

  • huynht
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    View and share information at: http://www.eqclearinghouse.org/2014-08-24-south-napa/

    Earthquake Data Map

    All information shared with the Clearinghouse is being collected in a Google Earth KMZ file. You can download the file here: https://drive.google.com/folderview?id=0B_skoYqbxPVHdlBiSm9IYkNpUDg&usp=sharing. There are many layers contained in this file and by default most are turned off.

    View Data Online

    You can also view the data online in the: ARCGIS DATA MAP

    Submit Data

    Add data while in the field using the Clearinghouse Field Notes Application and view Fieldnotes data map with photos.

  • oskin
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    The lineament visible on the radar east of the main rupture lies directly on the mapped trace of the airport strand of the west Napa fault. As far as I know this rupture has not been mapped in the field. I am not familiar with the COSMO-Skymed instrument. Looks like a little more than 1/2 fringe of displacement. Assuming pure RL slip, how much may there be? 

  • shyun
    2014.08.24 - M6.0 South Napa Earthquake, California   5 years 25 weeks ago

    Good morning. I posted a kmz and a snapshot of COSMO-SkyMed coseismic interferogram at the following URLs. The zoomable wrapped interferogram can help locating surface ruptures. For example, there seems to be one about 2.5 km east from the epicenter, running parallel to what Mike Oskin mapped.

    http://aria-share.jpl.nasa.gov/events/20140824-napa/ARIA_NapaEQ_CSK_D74_...

    http://aria-share.jpl.nasa.gov/events/20140824-napa/ARIA_NapaEQ_CSK_D74_...

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