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  • beroza
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    == SHAKEOUT SCENARIO: AFTERSHOCK PROBABILITY REPORT ==

     Southern California Seismic Network: a cooperative project of

     U.S. Geological Survey, Pasadena, California

     Caltech Seismological Laboratory, Pasadena, California

     Version 1: This report supersedes any earlier probability reports about this event.

     

      PRINCIPAL EARTHQUAKE PARAMETERS

    _______________________________

      Magnitude       :   6.7  Ml

     Time                :    15 October 2009   10:15:00 AM PDT

                            :   15 October 2009   18:15:00 UTC

     Coordinates      :   33 deg. 25.2 min. N,  115 deg.  50.4 min. W

    Depth                :    6.3 miles (   10 km)

    Location Quality  : Excellent

     

                      1 mi. Bombay Beach, CA

                      2 mi.  Coachella Valley, CA

     

    More Information about this SCENARIO  event and other earthquakes is available at

     

    http://earthquake.usgs.gov/eqcenter/eqinthenews/2008/shakeout/

     

     

     STRONG AFTERSHOCKS (Magnitude 5 and larger) -

     At this time (immediately after the mainshock) the probability of a

     strong and possibly damaging aftershock IN THE NEXT 7 DAYS is

      greater than 85 PERCENT.

     

     EARTHQUAKES LARGER THAN THE MAINSHOCK -

     Most likely, the recent mainshock will be the largest in the sequence.

     However, there is a small chance (APPROXIMATELY 5 TO 10 PERCENT) of an

     earthquake equal to or larger than this mainshock in the next 7 days.

     

     WEAK AFTERSHOCKS (Magnitude 3 to 5) -

     In addition, up to approximately 300 SMALL AFTERSHOCKS are expected in

     the same 7-DAY PERIOD and may be felt locally.

     

     This probability report is based on the statistics of aftershocks typical for

     California.  This is not an exact prediction, but only a rough guide to

     expected aftershock activity. This probability report may be revised as more

     information becomes available.

     

     

                     Background Information About Aftershocks

     

     Like most earthquakes, the recent earthquake is expected to be followed

     by numerous aftershocks.  Aftershocks are additional earthquakes that

     occur after the mainshock and in the same geographic area.  Usually,

     aftershocks are smaller than the mainshock, but occasionally an

     aftershock may be strong enough to be felt widely throughout the area

     and may cause additional damage, particularly to structures already

     weakened in the mainshock.  As a rule of thumb, aftershocks of

     magnitude 5 and larger are considered potentially damaging.

     

     Aftershocks are most common immediately after the mainshock; their

     average number per day decreases rapidly as time passes.  Aftershocks

     are most likely to be felt in the first few days after the mainshock,

     but may be felt weeks, months, or even years afterwards.  In general,

     the larger the mainshock, the longer its aftershocks will be felt.

     

     Aftershocks tend to occur near the mainshock, but the exact geographic

     pattern of the aftershocks varies from earthquake to earthquake and is

     not predictable.  The larger the mainshock, the larger the area of

     aftershocks.  While there is no "hard" cutoff distance beyond which an

     earthquake is totally incapable of triggering an aftershock, the vast

     majority of aftershocks are located close to the mainshock.  As a rule

     of thumb, a magnitude 6 mainshock may have aftershocks up to 10 to 20

     miles away, while a magnitude 7 mainshock may have aftershocks as far

     as 30 to 50 miles away.

  • tjordan
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

     

  • tjordan
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    Lots of activity here in SoCal. We hit 6.9 registered participants before the event (a form of mass earthquake prediction).

  • beroza
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    Update from USHS indicates a larger event, consistent with your experience.

  • beroza
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    == SHAKEOUT SCENARIO PRELIMINARY EARTHQUAKE REPORT ==

     

                       California Integrated Seismic Network

                              http://www.cisn.org

                         USGS/Caltech/CGS/UCB/UCSD/UNR

     

    Version 2: This report supersedes any earlier reports about this event.

     

    This is a computer-generated message and has not yet been reviewed by a

    seismologist.

     

    PRINCIPAL EARTHQUAKE PARAMETERS:  UPDATE

    ______________________________

    _

      Magnitude       :   7.4  ME

     Time                :    15 October 2009   10:15:00 AM PDT

                            :   15 October 2009   18:15:00 UTC

     Coordinates      :   33 deg. 25.2 min. N,  115 deg.  50.4 min. W

    Depth                :    6.3 miles (   10 km)

    Location Quality  : Excellent

     

                      1 mi. Bombay Beach, CA

                      6 mi.  Coachella Valley, CA

     

    More Information about this SCENARIO  event and other earthquakes is available at

     

    http://earthquake.usgs.gov/eqcenter/eqinthenews/2008/shakeout/

     

    ADDITIONAL EARTHQUAKE PARAMETERS

    ________________________________

    rms misfit                   :  0.47 seconds

    horizontal location error    :   0.3 km

    vertical location error      :   0.6 km

    maximum azimuthal gap        :    28 degrees

    distance to nearest station  :   6.0 km

    event ID                     : 999

     

    SOURCE OF INFORMATION/CONTACTS

    ________________________________

     

    CISN Southern California Management Center

     

            Caltech Seismological Laboratory

            U.S. Geological Survey

     

            http://www.cisn.org/scmc.html

  • mblanpied
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    Dave Applegate, Mike Blanpied and Peter Lyttle (acting Associate Director for Geology) online in Reston.

  • gareth
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    Shaking lasted ~ 1 minute here in Riverside. Will try and extricate our GPS receivers and sat phone from the building. Await further information as to corrdinating our response.

  • beroza
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

       I just got report of a large earthquake in the Salton Trough.  Was this large enough to be felt in Los Angeles?

  • huynht
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    ... and just got out from under my desk.

  • beroza
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    Normal.dotm 0 0 1 242 1383 Stanford University 11 2 1698 12.0 0 false 18 pt 18 pt 0 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;}

    == SHAKEOUT SCENARIO PRELIMINARY EARTHQUAKE REPORT ==

                       California Integrated Seismic Network

                              http://www.cisn.org

                         USGS/Caltech/CGS/UCB/UCSD/UNR

     

    Version 1: This report supersedes any earlier reports about this event.

     

    This is a computer-generated message and has not yet been reviewed by a

    seismologist.

     

    PRINCIPAL EARTHQUAKE PARAMETERS

    ______________________________

    _

      Magnitude       :   6.7  Ml

     Time                :    15 October 2009   10:15:00 AM PDT

                            :   15 October 2009   18:15:00 UTC

     Coordinates      :   33 deg. 25.2 min. N,  115 deg.  50.4 min. W

    Depth                :    6.3 miles (   10 km)

    Location Quality  : Excellent

     

                      1 mi.  Coachella Valley, CA

                      5 mi. Bombay Beach, CA

     

     

    More Information about this SCENARIO  event and other earthquakes is available at

     

    http://earthquake.usgs.gov/eqcenter/eqinthenews/2008/shakeout/

     

    ADDITIONAL EARTHQUAKE PARAMETERS

    ________________________________

    rms misfit                   :  0.47 seconds

    horizontal location error    :   0.3 km

    vertical location error      :   0.6 km

    maximum azimuthal gap        :    28 degrees

    distance to nearest station  :   6.0 km

    event ID                     : 999

     

    SOURCE OF INFORMATION/CONTACTS

    ________________________________

     

    CISN Southern California Management Center

     

            Caltech Seismological Laboratory

            U.S. Geological Survey

     

            http://www.cisn.org/scmc.html

     

    ________________________________

    _______________________________________________

    Duty mailing list

    Duty@scsnmail.gps.caltech.edu

    http://unix1.gps.caltech.edu/mailman/listinfo/duty

  • mcraney
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    CNN just reported a big earthquake in California.  I am on line here in Stamford, CT.  John

  • tjordan
    2009.10.15-Great California ShakeOut   12 years 44 weeks ago

    A large earthquake has happened in Southern California with strong shaking of long duration (> 1 min) felt at USC. We are bringing up a new event page on the SCEC ERCMS to coordinate SCEC activities related to this event.
     
    For issues related to inter-organizational coordination, please respond to this thread. Greg Beroza will coordinate SCEC earthquake response operations, and separate threads will be initiated by group leaders for coordination of specific seismology, geodesy, and geology earthquake response activities.
     

  • hudnut
    2009.10.01-Olancha   12 years 44 weeks ago
  • eyu
    Information Flow Diagram   12 years 49 weeks ago

    That's correct - I was trying to say a user has a file, and sends it to an email list.  Later on the user revises the file (file v2) - but this time perhaps only sends to some people. 

  • huynht
    Information Flow Diagram   12 years 49 weeks ago

    I like the before/after approach of this diagram, and the summary of benefits to the user. I assume "file v1" refers to some file, version 1? Maybe this can be made a little clearer - with some example file types?

  • hudnut
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    This new version overlays all of the previous layers plus updated seismicity (thanks again to Egill Hauksson for re-locations and to Duncan Agnew and Bob Dollar for KMZ files). The caption is copied below. The Extra fault zone mapping by Susanne Janecke and others on-land has been augmented with mapping from the offshore work in the Salton Sea by Danny Brothers, Graham Kent and Neal Driscoll of UCSD/Scripps. This work is as-yet-unpublished, and is compiled here along with other data for use in earthquake response, scientific coordination and planning purposes. Please contact Danny Brothers with any questions or requests for additional information about this important new data set - this map was presented at the Fall 2008 AGU meeting (abstract attached below) and has been provided with a request for proper attribution. They are preparing a paper on this, and for now please cite the AGU abstract as follows: Brothers, D., N. Driscoll, G. Kent (2008), New constraints on the tectonic evolution of the Salton Trough, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract T11A-1840 EM: dbrother@ucsd.edu AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0225, United States AU: Driscoll, N EM: ndriscoll@ucsd.edu AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0225, United States AU: Kent, G EM: gkent@ucsd.edu AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0225, United States AB: The Salton Trough is a critical structure where two very different styles of deformation meet; spreading-center dominated deformation to the south in the Gulf of California and dextral strike-slip deformation along the San Andreas fault system(SAF) to the north. Seismic CHIRP data acquired in the Salton Sea provide new constraints on the interaction between the San Andreas, San Jacinto and Imperial fault systems and reveal distinct changes in deformational style from north to south. Based on the stratal geometry observed in CHIRP profiles, we propose three distinct phases of tectonic deformation: (1) Late- Pleistocene transpression north of the Extra Fault Zone (EFZ) replaced by (2) late-Holocene differential subsidence south of the EFZ and (3) recent formation of the Brawley Seismic Zone (BSZ), a through-going crustal shear zone. An angular unconformity is observed to separate the folded and faulted (late?) Pleistocene strata of the Brawley Formation from the overlying Holocene Cahuilla Formation (CF). North of the EFZ reflectors in the CF suggest little to no active deformation. Conversely, south of the EFZ reflectors exhibit marked divergence with their dip systematically increasing with depth. Such a pattern of divergence indicates that the rate of sedimentation has kept pace with the rate of tectonically-induced accommodation. As such, it appears that the EFZ is a tectonic hinge zone delineating the northern limit of active subsidence, high heat flow, and volcanism. Furthermore, given the observed subsidence pattern, we predict the existence of a NE trending basin-bounding normal fault, or series of normal faults, near the southern shoreline of the Salton Sea. In our conceptual model, the early distributed faulting and transrotation between the San Andreas and San Jacinto faults accounts for the compressional folding observed in the Brawley Formation, but later gave way to extension-dominated deformation as significant slip became focused along the Imperial Fault. Reactivation of Miocene extensional structures by the Imperial � San Andreas releasing bend may account for the differential subsidence in the southern sea. In addition, we propose that the BSZ is a young feature similar to through-going shear zones formed in pull-apart basin analog models. We suggest that seismicity patterns in the BSZ do not reflect the dominant tectonic processes or kinematics occurring beneath the Salton Sea, but rather short-term, low magnitude stress release. Finally, we have established a chronostratigraphic framework for the Salton Sea by correlating seismic horizons in the CHIRP data with Lake Cahuilla stratigraphy observed in onshore paleoseismic excavations. The EFZ shows evidence for multiple events during the last ~1,500 years, and the most recent event occurred ~1700 AD, suggesting the potential for coincident ruptures along the SAF and EFZ. Initial estimates suggest that the vertical subsidence rate across the EFZ has been ~ 6 mm/yr for the last 800 years. Modified version of figure caption: The latest events are shown as blue circles (precisely re-located as of 3/26/09 9 a.m. local time by Egill Hauksson of Caltech). In red are the Nov. 2001 sequence events. The latest activity occurred near the intersection of the San Andreas fault and the northeastward projection of the Extra fault zone, near the northern end of the Brawley Seismic Zone. This area has been seismically active previously in Oct. 1999 (Hough and Kanamori, 2002) and Nov. 2001. It has also been noted as being potentially significant for future rupture of the southern San Andreas fault (e.g., Hudnut et al., 1989). Active faults are shown in red if they have ruptured historically (the Elmore Ranch fault zone broke in Nov. 1987, and the Coyote Creek fault broke in 1968). Also shown in orange are faults that have been mapped and that have exhibited triggered creep during regional earthquakes. These include the San Andreas fault and Extra fault zone [data of Susanne U. Janecke, unpublished mapping, Kirby 2005 MS thesis, and Kirby et al. (2007). Additional faults are being mapped.] Other features shown are volcanic centers (orange circles) and various mud pots, carbon dioxide vents (green symbols; from Lynch & Hudnut, 2008).
  • pagem
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    Here is a similar plot with the rates from the Nov.13-14 2001 swarm that is in nearly the same location. I'm also including a magnitude distribution plot for Nov. 13th seismicity prior to the M4.2 earthquake, since at the time there was some worry that the sequence was missing small (less the M3) events.
  • pagem
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    Here is a plot that shows the magnitude distribution & rate vs. time plot for the Bombay Bech swarm activity as of this morning. -- Morgan Page
  • hudnut
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    Duncan has an SRL paper nearing publication on this (in press?), and if you have questions please contact him. He asked that I go ahead and load this file to the SCEC wiki because he is awaiting access and can't yet post the file himself. The wiki does not allow .kmz file extensions to be uploaded, so I changed the filename to end in .jpg instead. In order to get this file to work in Google Earth, you will need to manually change the filename extension from .jpg back to .kmz. Let me know if you have any problems, or request the file from Duncan by e-mail (dagnew@ucsd.edu)
  • hudnut
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    Ken: Here is the NS data from DHL. The gap was caused by the 4.8 event. The burst of low-frequency noise before and after the start of day 82 is from wind: note that this is 1-s data, not the filtered 5-m data we usually show, so the thickness of the trace comes from microseisms; symmetrical spikes are earthquakes, and downward spikes are trains going by. No signal that I can see! Note also that since we couldn't record a coseismic offset, the offset across the gap is just set to zero. I still can't get into the SCEC Response area, but you are welcome to post this and the seismicity KMZ file. Thanks Duncan
  • hudnut
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 20 weeks ago
    Some initial automated locations later get revised - this may be one such example. These usually get corrected within a pretty short time, say, tens of minutes. Doug Given was explaining this after I noticed a few occurrences of revisions over the past few days. He'd be the best person to ask.
  • jmcguire
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 21 weeks ago
    it's just the skewness in the time domain (i.e. normalized third-central moment of the moment-rate history). We haven't done any magnitude anomaly detectors for this one yet, but based on experience this swarm would be way beyond 2-sigma in terms of being an anomaly on a standard ETAS transformed-time plot.
  • jmcguire
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 21 weeks ago
    Anyone know if that recent M1.7 was on the SAF or just hard to locate well? 1.7 2009/03/26 12:29:13 33.386N 115.765W 13.7 5 km ( 3 mi) NW of Bombay Beach, CA
  • tjordan
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 21 weeks ago
    I like this way of displaying sequences. I assume it's a time skewness and not a skewness in moment distribution (e.g., relative to a nominal beta value). Have you also plotted the latter?
  • hudnut
    2009.03.24-Bombay Beach Earthquake Sequence   13 years 21 weeks ago
    This event at 8:25 p.m. last night has been revised to M 4.0 by SCSN.