SCSNby Zackary Newman – SCSN http://www.scsn.org Southern California Seismic Network Wed, 30 May 2018 20:02:37 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.2 05/30/2018, M3.8 near Thousand Palms ../../../../index.php/2018/05/30/05-30-2018-m3-8-near-thousand-palms/ ../../../../index.php/2018/05/30/05-30-2018-m3-8-near-thousand-palms/#respond Wed, 30 May 2018 19:35:31 +0000 http://www.scsn.org/?p=2783 ]]>
  • 30 May 2018 12:22:05 PDT, (33.924, -116.323), depth 9.5km, 13km NNE of Thousand Palms, California
  • Aftershocks: so far (30 May 2018, 12:33PM PDT) there have been 2 aftershocks recorded, the largest M1.2 (smallest M0.9). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 1 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M0.6 (2018/05/30).
  • Historical seismicity: since our records began in 1932 we’ve had 88 events of M4 or greater within 10km of today’s event, the largest was M6.1 (1992/04/23) and the most recent was M4.0 on 06 Aug 2010.
  • Nearby faults: unnamed Fault in the Little San Bernardino Mountains (1.4 km), Blue Cut fault zone (Blue Cut fault) (2.2 km), Eureka Peak fault (5.0 km), San Andreas fault zone, San Bernardino Mountains section (North Branch SAF) (6.6 km), Burnt Mountain fault zone (East Wide Canyon fault) (6.8 km), San Andreas fault zone, San Bernardino Mountains section (6.8 km), Indio Hills fault zone (9.2 km), San Andreas fault zone, San Bernardino Mountains section (South Branch SAF) (9.5 km) and Long Canyon fault (10.9 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.The closest station to the earthquake shown in the view is CI.WWC in Palm Springs at approximately 8km from the epicenter.

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    05/08/2018, M4.5 near Cabazon ../../../../index.php/2018/05/08/05-08-2018-m4-5-near-cabazon/ ../../../../index.php/2018/05/08/05-08-2018-m4-5-near-cabazon/#respond Tue, 08 May 2018 13:57:59 +0000 http://www.scsn.org/?p=2711 ]]> Last updated May 30th, 2018

    A M4.5 earthquake occurred at 4:49 local time this morning (May 8) under the San Bernardino Mountains, near a complex part of the San Andreas fault. Seismologists call this region the “San Gorgonio knot” because so many small faults intersect here and the main San Andreas trace is not clearly defined.

    Historically, this area around Mt. San Gorgonio is the only part of the southern San Andreas fault that produces smaller quakes. Many M3-4 earthquakes have been recorded here. The largest were the M6.0 Desert Hot Springs earthquake in 1948 about 30 miles to the east and the 1986 M5.9 North Palm Springs earthquake that was less than 10 miles east of today’s earthquake.

    The focal mechanism calculated by Caltech and the USGS for this earthquake Moment Tensor Page shows the event happened on a fault that strikes a little north of east-west and that the motion was primarily thrust faulting. This means that the north side moved up and over the lower south side of the fault. This is very similar to the motion we saw in the 1986 North Palm Springs earthquake. (https://authors.library.caltech.edu/48710/.)

    This morning’s M4.5 was felt from San Diego to Los Angeles. More than 10,000 people have reported feeling it at Did you feel it?. The strongest shaking recorded by the instruments is Intensity VI.

    This size earthquake is common in California, happening many times each year somewhere in the state. This is normal activity and has no relationship to the Hawaii eruption.

    Technical information about this earthquake and its aftershocks:

    • 08 May 2018 04:49:34 PDT, (34.017, -116.780), depth 12.9km, 11km N of Cabazon, California.
    • Aftershocks: so far (09 May 2018, 10:40AM PDT) there have been 88 aftershocks recorded, the largest M3.2 (smallest M0.2). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
    • Plot of seismicity through time, from 0.5 days before the M4.5 Cabazon event to approximately 1.25 days after. Top plot shows cumulative earthquake count against time. Bottom plot shows earthquake magnitude against time, the M4.5 event and M3.2 aftershock are plotted as red stars.
      Map showing the M4.5 earthquake near Cabazon (red star) with foreshocks and aftershocks in a 10km radius shown as circles colored by time (blue = early, red = late) and sized by magnitude. Grey stars labelled by magnitude show historic earthquakes. Grey lines show the mapped fault strands in the San Andreas fault zone.
    • Historical seismicity: since our records began in 1932 we’ve had 46 events of M4 or greater within 10km of today’s event, the largest was M6.0 (1986/07/08) and the most recent was M4.4 on 06 Jan 2016.
    • Nearby faults: San Andreas fault zone, San Bernardino Mountains section (3.0 km).
    • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
    • Visit our special reports page for further information on local notable earthquakes.

    Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.The closest station to the earthquake shown in the view is CI.WWC in Palm Springs at approximately 35km.

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    04/16/2018, M3.8 near Grapevine ../../../../index.php/2018/04/16/04-16-2018-m3-8-near-grapevine/ ../../../../index.php/2018/04/16/04-16-2018-m3-8-near-grapevine/#respond Mon, 16 Apr 2018 17:11:12 +0000 http://www.scsn.org/?p=2675 ]]>
  • 16 Apr 2018 09:36:48 PDT, (35.043, -119.042), depth 7.7km, 15km NW of Grapevine, California.
  • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. The following 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.
    • 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 less than 10%
    • 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%) 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 2 SMALL AFTERSHOCKS are expected in the same 7-DAY PERIOD and may be felt locally.
  • Historical seismicity: since our records began in 1932 we’ve had 103 events of M4 or greater within 10km of today’s event, the largest was M7.5 (1952/07/21) and the most recent was M4.2 on 22 Sep 2005. Known as the Kern County earthquake, the Mw7.5 event on July 21, 1952 caused widespread damage and was felt across California and Nevada. See the special report on the SCEDC website for more information. Many of the other catalog events in this area are aftershocks of the 1952 Kern County earthquake. The M3.7 earthquake near Bodfish on April 13, 2018, was located approximately 60 km from this event near Grapevine, but is also along the section of fault responsible for the Kern County earthquake.
  • Nearby faults: Wheeler Ridge fault zone (Wheeler Ridge fault) (1.5 km), Pleito fault zone, western Pleito section (Pleito fault) (3.8 km), unnamed faults (1952 earthquake fractures) (4.2 km), Pleito fault zone, eastern Pleito section (Pleito fault) (5.9 km) and Pleito fault zone, western Pleito section (Oak Hill thrust) (13.5 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

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    03/07/2018, M3.7 near Simmler ../../../../index.php/2018/03/07/03-07-2018-m3-7-near-simmler/ ../../../../index.php/2018/03/07/03-07-2018-m3-7-near-simmler/#respond Wed, 07 Mar 2018 18:43:19 +0000 http://www.scsn.org/?p=2618 ]]>
  • 07 Mar 2018 10:05:00 PST, (35.485, -120.027), depth 8.5km, 15km N of Simmler, California
  • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%%) that a larger quake could occur, with the likelihood decreasing over time.
  • Nearby faults: San Andreas fault zone, Cholame-Carrizo section (0.6 km), San Juan fault zone (12.7 km) and San Juan fault zone (San Juan fault) (13.9 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.The closest station to the epicenter represented below is CI.SMR at 54km away

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    01/25/2018, M4.0 near Trabuco Canyon ../../../../index.php/2018/01/25/01-25-2018-m4-0-near-trabuco-canyon/ ../../../../index.php/2018/01/25/01-25-2018-m4-0-near-trabuco-canyon/#respond Thu, 25 Jan 2018 14:54:35 +0000 http://www.scsn.org/?p=2560 ]]> Last updated January 29th, 2018

    • 25 Jan 2018 02:09:56 PST, (33.742, -117.492), depth 11.2km, 12km NE of Trabuco Canyon, California
    • Aftershocks: so far (29 Jan 2018, 08:12AM PST) there have been 27 aftershocks recorded, the largest M3.1 (smallest M0.3). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
    • There was 1 event during the 3 days prior to the earthquake (within a 10 km radius), with M1.2 (2018/01/22).
    • Plot of seismicity through time, from 3 days before the M4.0 Trabuco Canyon event to approximately 3.5 days after. Top plot shows cumulative earthquake count against time. Bottom plot shows earthquake magnitude against time, the M4.0 event and M3.1 aftershock are plotted as red stars.

    • Historical seismicity: since our records began in 1932 we’ve had 7 events of M4 or greater within 10km of today’s event, the largest was M5.2 (1938/05/31) and the most recent was M4.7 on 02 Sep 2007.
    • Map showing the M4.0 earthquake near Trabuco Canyon (red star) with foreshocks and aftershocks in a 10km radius shown as circles colored by time (blue = early, red = late) and sized by magnitude. Grey stars labelled by magnitude show historic earthquakes. Grey lines show the mapped fault strands in the Elsinore fault zone.

    • Mechanism: the event has a thrust mechanism on a near east-west trending fault plane as shown by the moment tensor below.
      Moment tensor for the M4.0 event on 25 Jan 2018 near Trabuco Canyon.

      The nearest mapped faults to this event are in the Elsinore fault zone, most strands of which usually host strike-slip events. However, the Glen Ivy strands of the Elsinore fault show oblique as well as strike-slip mechanisms (as shown below), and in the region north of Lake Elsinore it is thought the fault may form a restraining bend at depth contributing to uplift of the Santa Ana mountains (Hull & Nicholson, 1992) and consistent with thrust mechanisms such as the 2018/01/25 earthquake.

      Figure from Hull & Nicholson (1992) showing focal mechanisms for selected earthquakes from the Elsinore-Temecula trough. The M4.0 event on 25 Jan 2018 near Trabuco Canyon has been added as a red star, and shows a consistent mechanism with earlier observed earthquakes.

    • Nearby faults: Elsinore fault zone, Glen Ivy section (Glen Ivy South fault) (0.9 km), Elsinore fault zone, Glen Ivy section (Glen Ivy North fault) (1.4 km), Elsinore fault zone, Temecula section (Willard fault) (2.0 km), Elsinore fault zone, Glen Ivy section (Eagle fault) (5.6 km), Elsinore fault zone, Glen Ivy section (Main Street fault) (10.7 km), Elsinore fault zone, Chino section (Chino fault) (12.8 km) and Elsinore fault zone, Temecula section (Wildomar fault) (13.1 km).
    • The ShakeMap (below) shows that ground shaking was strongest to the north and east of the earthquake hypocenter, consistent with stronger shaking being felt in basins and valleys (generally weaker geology, greater chance of amplification effects), and potentially also an effect of source mechanism.
      ShakeMap for the M4.0 event on 25 Jan 2018 near Trabuco Canyon.

    • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
    • Visit our special reports page for further information on local notable earthquakes.

    Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

  • References:
    Hull, A.G. & C. Nicholson, 1992. Seismotectonics of the Northern Elsinore Fault Zone, Southern California. Bull. Seismo. Soc. Am. 82 (2) pp. 800-818.
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    10/26/2017, M3.7 near Avalon ../../../../index.php/2017/10/27/10262017-m3-7-near-avalon/ ../../../../index.php/2017/10/27/10262017-m3-7-near-avalon/#respond Fri, 27 Oct 2017 19:53:00 +0000 http://www.scsn.org/?p=2513 ]]>
  • 26 Oct 2017 16:18:28 PDT, (33.462, -118.183), depth 10.7km, 19km NE of Avalon, California
  • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%%) that a larger quake could occur, with the likelihood decreasing over time.
  • Historical seismicity: since our records began in 1932 we’ve had 4 events of M4 or greater within 10km of today’s event, the largest was M4.8 (1988/11/20) and the most recent was M4.8 on 20 Nov 1988.
  • Nearby faults: Coronado Bank fault zone, Coronado Bank-Palos Verdes section (9.8 km), Palos Verdes fault zone, San Pedro shelf section (Palos Verdes fault) (11.0 km) and Santa Cruz_Santa Catalina Ridge fault zone (26.2 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

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    10/24/2017, M3.9 near San Clemente Is ../../../../index.php/2017/10/24/10242017-m3-9-near-san-clemente-is/ ../../../../index.php/2017/10/24/10242017-m3-9-near-san-clemente-is/#respond Tue, 24 Oct 2017 13:40:59 +0000 http://www.scsn.org/?p=2320 ]]>
  • 24 Oct 2017 00:00:51 PDT, (33.173, -118.722), depth 4.8km (fixed), 19km NW of San Clemente Is.
  • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • Historical seismicity: since our records began in 1932 we’ve had 1 events of M4 or greater within 10km of today’s event, the largest and most recent was M4.1 on 21 Oct 1932.
  • Nearby faults: San Clemente fault zone (San Clemente fault) (3.5 km) and Santa Cruz_Santa Catalina Ridge fault zone (21.7 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed. The closest stations represented in this display are CI.RPV and CI.DJJ at 70km and 107km away from the epicenter.

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    09/19/2017, M3.7 near Little Lake ../../../../index.php/2017/09/19/09192017-m3-7-event-near-little-lake/ ../../../../index.php/2017/09/19/09192017-m3-7-event-near-little-lake/#respond Tue, 19 Sep 2017 19:42:48 +0000 http://www.scsn.org/?p=2251 ]]> Last updated October 24th, 2017

    • 19 Sep 2017 11:45:43 PDT, (36.020, -117.770), depth 1.8km, 15km NE of Little Lake, California
    • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%%) that a larger quake could occur, with the likelihood decreasing over time.
    • There were 19 events during the 3 days prior to the earthquake (within a 15 km radius), the largest was M3.2 (2017/09/19).
    • Historical seismicity: since our records began in 1932 we’ve had 21 events of M4 or greater within 10km of today’s event, the largest was M5.3 (1996/11/27) and the most recent was M4.0 on 15 Feb 2010.
    • Nearby faults: Airport Lake fault zone (0.0 km), Unnamed fault near Coso Basin (4.9 km) and Unnamed fault east of Rose Valley (7.1 km).
    • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
    • Visit our special reports page for further information on local notable earthquakes.

    Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed. The closest station represented in this feed is CI.CLC, 27km away from the epicenter.

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    09/18/2017, M3.6 near Westwood ../../../../index.php/2017/09/19/09182017-m3-6-event-near-westwood/ ../../../../index.php/2017/09/19/09182017-m3-6-event-near-westwood/#respond Tue, 19 Sep 2017 14:14:06 +0000 http://www.scsn.org/?p=2249 ]]> Last updated October 24th, 2017

    • 18 Sep 2017 23:20:44 PDT, (34.087, -118.475), depth 10.5km, 5km NW of Westwood, California
    • Aftershocks: so far (19 Sep 2017, 07:09AM PDT) there has been 1 aftershock recorded, M2.0. More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
    • Historical seismicity: since our records began in 1932 we’ve had 4 events of M4 or greater within 10km of today’s event, the largest was M4.5 (1994/01/19) and the most recent was M4.2 on 02 Jun 2014.
    • Nearby faults: Santa Monica fault (4.7 km), Hollywood fault (6.0 km), Newport-Inglewood-Rose Canyon fault zone, north Los Angeles basin section (10.8 km), Santa Monica fault (offshore) (11.5 km), Charnock fault (12.3 km) and Palos Verdes fault zone, Santa Monica Basin section (Palos Verdes fault) (13.7 km).
    • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
    • Visit our special reports page for further information on local notable earthquakes.

    Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.The closest stations represented in the feed are CI.DJJ and CI.RPV at 2.9m and 38.7m away from the epicenter respectively.

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    08/22/2017, M4.1 near Trona ../../../../index.php/2017/08/22/08222017-m4-1-event-near-trona/ ../../../../index.php/2017/08/22/08222017-m4-1-event-near-trona/#respond Tue, 22 Aug 2017 20:18:58 +0000 http://www.scsn.org/?p=2243 ]]> Last updated October 24th, 2017

    • 22 Aug 2017 12:51:59 PDT, (35.905, -116.922), depth 5.3km, 44km ENE of Trona, California
    • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%%) that a larger quake could occur, with the likelihood decreasing over time.
    • Historical seismicity: since our records began in 1932 we’ve had 2 events of M4 or greater within 10km of today’s event, the largest was M4.8 (1953/11/24) and the most recent was M4.1 on 01 Mar 2013.
    • Nearby faults: unnamed West Side faults (9.1 km) and Panamint Valley fault zone, Brown Mountain section (14.0 km).
    • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
    • Visit our special reports page for further information on local notable earthquakes.

    Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.The closest stations represented in the feed is CI.CLC and CI.FUR, 61.7km and 62.8km away from the epicenter respectively.

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