SCSNM4.0 – SCSN http://www.scsn.org Southern California Seismic Network Wed, 05 Dec 2018 22:51:26 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.2 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 ]]>
  • 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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    12/06/2017, M4.0 near Julian ../../../../index.php/2017/12/07/12062017-m4-0-near-julian/ ../../../../index.php/2017/12/07/12062017-m4-0-near-julian/#respond Thu, 07 Dec 2017 02:27:48 +0000 http://www.scsn.org/?p=2529 ]]>
  • A number of felt earthquakes have occurred near Julian, California, four with magnitude three or above:
    • M4.0, 06 Dec 2017 16:33:15 PST, (33.148, -116.480), depth 11.1km, 14km NE of Julian, California
    • M3.0, 06 Dec 2017 16:38:03 PST, (33.150, -116.482), depth 11.1km, 14km NE of Julian, California
    • M3.6, 06 Dec 2017 19:57:38 PST, (33.150, -116.480), depth 11.4km, 14km NE of Julian, California
    • M3.5, 07 Dec 2017 02:32:47 PST, (33.147, -116.478), depth 11.0km, 14km ENE of Julian, California
  • Aftershocks: so far (07 Dec 2017, 08:00AM PST) there have been 76 aftershocks recorded for the M4.0 event, the largest M3.6 (smallest M0.6). 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.
  • Cumulative event number against time (top) and magnitude against time (bottom) for the events near Julian on 6-7 December 2017. In the lower plot, red stars mark the four events with magnitude three or above.
  • There were 3 events during the 3 days prior to the earthquake (within a 15 km radius), the largest was M2.6 (2017/12/07).
  • Historical seismicity: since our records began in 1932 we’ve had 9 events of M4 or greater within 10km of today’s event, the largest was M4.7 (1957/01/24) and the most recent was M4.5 on 10 Oct 1984.
  • Nearby faults: Elsinore fault zone, Julian section (Earthquake Valley fault) (3.5 km), Elsinore fault zone, Earthquake Valley fault, Julian section (4.3 km) and Elsinore fault zone, Julian section (Elsinore fault) (10.0 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 shown to the event is CI.DGR at approximately 75km, and the furthest is CI.MLAC at more than 500km.

    Below is a playlist of the waveform data associated with this sequence, as recorded in our Live Seismograms Feed. The closest station shown to the event is CI.DGR at approximately 75km, and the furthest is CI.MLAC at more than 500km. More videos may be added as new events occur.

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    03/22/2017, M4.0 near Alberto Oviedo Mota ../../../../index.php/2017/03/22/03222017-m4-0-event-near-alberto-oviedo-mota/ ../../../../index.php/2017/03/22/03222017-m4-0-event-near-alberto-oviedo-mota/#respond Wed, 22 Mar 2017 20:40:24 +0000 http://www.scsn.org/?p=2112 ]]>
  • 22 Mar 2017 11:57:32 PDT, (32.225, -115.228), depth 18.5km, 6km W of Alberto Oviedo Mota, B.C., Mexico
  • Aftershocks: so far (22 Mar 2017, 01:26PM PDT) there has been 1 aftershock recorded, M3.8. 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 93 events of M4 or greater within 10km of today’s event, the largest was M7.2 (2010/04/04) and the most recent was M4.1 on 17 Apr 2013.
  • 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 shown here is CI.RXH, approximately 113 km from the epicenter.

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    12/28/2016, M4.0 near Morongo Valley ../../../../index.php/2016/12/28/12282016-m4-0-event-near-morongo-valley/ ../../../../index.php/2016/12/28/12282016-m4-0-event-near-morongo-valley/#respond Wed, 28 Dec 2016 18:09:13 +0000 http://www.scsn.org/?p=1846 ]]>
  • 28 Dec 2016 09:56:59 PST, (34.152, -116.707), depth 10.1km, 16km NW of Morongo Valley, California
  • Aftershocks: so far there have been 7 aftershocks recorded. 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 2 events of M4 or greater within 10km of today’s event, the largest was M4.8 (30 Jun 1992).
  • Nearby faults: Santa Ana fault zone (Santa Ana fault) (4.2 km), Pinto Mountain fault zone (Pinto Mountain fault) (8.6 km), San Gorgonio Mountain fault (8.9 km), Helendale-South Lockhart fault zone, northern San Bernardino Mountains section (9.0 km), San Andreas fault zone, San Bernardino Mountains section (Mill Creek fault) (9.9 km), Pipes Canyon fault (10.3 km) and San Andreas fault zone, San Bernardino Mountains section (Mission Creek fault) (11.3 km).
  • Links for: USGS earthquake page, ShakeMap, DYFI.
  • Visit our special reports page for further information on local notable earthquakes.
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    07/31/2016, M4.0 near Westmorland ../../../../index.php/2016/08/02/07312016-m4-0-event-near-westmorland/ ../../../../index.php/2016/08/02/07312016-m4-0-event-near-westmorland/#respond Tue, 02 Aug 2016 20:29:46 +0000 http://www.scsn.org/?p=1596 ]]>
  • 31 Jul 2016 09:21:05 PDT, (32.958, -115.760), depth 3.2km, 16km SW of Westmorland, 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 2 events during the 3 days prior to the earthquake (within a 1 km radius), the largest was M2.6 (2016/07/31).
  • Historical seismicity: since our records began in 1932 we’ve had 15 events of M4 or greater within 10km of today’s event, the largest was M6.6 (1942/10/21) and the most recent was M4.7 on 28 Jan 1988.
  • Nearby faults: Superstition Hills flt, 1.3 km; Superstition Mountain section fault, 3.7 km; Lone Tree fault, 8.3 km; Wienert fault, 9.9 km; East Elmore Ranch fault, 10.7 km; and Elmore Ranch fault, 10.8 km; all within the Superstition Hills section of the San Jacinto fault zone.
  • Links for: USGS earthquake page, ShakeMap, DYFI.
  • Visit our special reports page for further information on local notable earthquakes.
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    9/16/2015, M4.0 Near Big Bear Lake ../../../../index.php/2015/09/23/16-september-2015-m4-0-event-near-big-bear-lake/ ../../../../index.php/2015/09/23/16-september-2015-m4-0-event-near-big-bear-lake/#respond Wed, 23 Sep 2015 19:31:53 +0000 http://www.scsn.org/?p=1145 ]]>
  • 16 Sep 2015 09:10:47 PDT, (34.139, -116.857), 13km SSE of Big Bear Lake, CA.
  • Initial magnitude was revised to M4.0 once all data became available and were analyzed.
  • Depth was about 11km (7 miles), and the event was widely felt (out to ~200km) with light to moderate shaking at the epicenter.
  • So far there have been a few small aftershocks: two over M2.0, the first within a few minutes of the M4.0. More may be expected, largest could be M3.0 if the M4.0 is the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • Focal mechanism and moment tensor solutions for the M4.0 show oblique normal motion. It is not possible to say exactly which fault at this time; local geology is complex and several large fault systems converge near this area (San Andreas, Pinto Mountain are within a few miles).
  • Events have occurred in this area historically, since our records began in 1932 we’ve had 22 events of M4 or greater within 10km of today’s event, the last was an M4.6 on 1 Oct 1995, many were aftershocks of the Landers earthquake in 1992.
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