SCSNAguanga – SCSN

12/04/2020, M3.8 near Aguanga

Zackary Newman — Tue, 08 Dec 2020 15:58:56 +0000

Event

04 Dec 2020 21:41:29 PST, (33.422, -116.932), depth 8.1km.
7km WSW of Aguanga, California

Aftershocks

As of 08 Dec 2020, 07:52AM PST, there have been 29 aftershocks recorded.
The largest was M1.7 (smallest M0.2).
More aftershocks 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 3 events of M4 or greater within 10km of today’s event.
The largest historic event was M4.4 on 2018/08/15.
The most recent historic event was M4.4 on 15 Aug 2018.

Faults

CFM fault associations: most likely Earthquake Valley fault; main segment (46%). Alternates: Not associated with a CFM modeled fault (4%), Other CFM faults (50%).*
Nearby faults: Agua Tibia Mountain fault zone (9.0 km), Elsinore fault zone, Julian section (Elsinore fault) (9.1 km), Elsinore fault zone, Temecula section (Wildomar fault) (9.4 km), Elsinore fault zone, Temecula section (Willard fault) (13.8 km) and Elsinore fault zone, Temecula section (Wolf Valley fault) (14.9 km).**

Additional Information

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.

*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

Probability: The probability in percent the earthquake is associated with this fault.

SCSN: Caltech/USGS Southern California Seismic Network

**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

11/09/2018, M3.8 near Aguanga

Duty Seismologist — Fri, 09 Nov 2018 15:25:56 +0000

Two events above M3.5 have occurred in the ongoing Cahuilla swarm:
- 09 Nov 2018 06:45:50 PST, (33.483, -116.802), depth 2.0km, 7km NE of Aguanga, California
- 09 Nov 2018 06:58:09 PST, (33.485, -116.803), depth 1.1km, 7km NE of Aguanga, California
Aftershocks: so far (09 Nov 2018, 02:04PM PST) there have been 87 aftershocks recorded since the second, larger event, the largest M2.0 (smallest M0.1). 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 91 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was the M3.7 (2018/11/09).
Historical seismicity: since our records began in 1932 we’ve had 14 events of M4 or greater within 10km of today’s event, the largest was M5.6 (2005/06/12) and the most recent was M4.4 on 15 Aug 2018. Since the onset of the Cahuilla swarm in 2016, we have now recorded over 9000 events.
Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
Visit our special reports page for further information on local notable earthquakes.

08/14/2018, M4.4 near Aguanga

Jennifer Andrews — Wed, 15 Aug 2018 01:42:19 +0000

14 Aug 2018 18:24:26 PDT, (33.477, -116.803), depth 1.9km, 7km NE of Aguanga, California
Aftershocks: so far (16 Aug 2018, 10:48AM PDT) there have been 435 aftershocks recorded, the largest M2.9 (smallest M0.0). 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.
There were 95 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M2.3 (2018/08/12). This area has been experiencing swarm activity for over 2 years (referred to as Cahuilla swarm), seeing elevated seismicity rates since early 2016. This region has hosted earthquake swarms since the 1980s, each lasting for weeks or a few months. The swarm starting early 2016 is the most prolific swarm recorded, with several thousand events observed so far.

2018 seismicity in the region of the Cahuilla swarm as of 15 August 2018. Circles plot individual earthquakes at all magnitudes in the SCSN catalogue, with size indicating magnitude. Events with magnitude 3.0 or greater are shown as red stars. The red line plots the cumulative number of events with magnitude 1.49 or greater.

Seismicity in the Cahuilla swarm from 1 day before the M4.4 event to approximately 40 hours after. Top plot shows the cumulative event number and the number of events per 20 minutes, both showing the aftershock event rate decay. Bottom plot shows event magnitudes against time.

Historical seismicity: since our records began in 1932 we’ve had 13 events of M4 or greater within 10km of today’s event, the largest was M5.6 (2005/06/12) and the most recent was M4.1 on 17 Nov 2008.
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.HMT2 near Anza-Borrego at approximately 30km from the epicenter.