Earthquake swarm near Salton Sea, S. California

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Discussion Overview

The discussion centers around a recent swarm of earthquakes near the Salton Sea in Southern California, exploring the geological context, potential implications for future seismic activity, and the relationship between smaller quakes and the likelihood of a larger event.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants note the occurrence of multiple earthquakes, including a magnitude 4.9 and a magnitude 4.5, and provide links to USGS data for further details.
  • One participant questions whether the swarm indicates a precursor to a larger earthquake, referred to as "the BIG one."
  • Another participant suggests that the situation is complex due to the presence of three significant faults and numerous minor ones, as well as the quakes occurring in an active spreading center.
  • A later reply argues that the occurrence of many smaller quakes may relieve stress and thus reduce the likelihood of a larger quake, challenging the initial concern about the swarm indicating an impending major event.

Areas of Agreement / Disagreement

Participants express differing views on whether the swarm of smaller earthquakes is a cause for concern regarding a larger seismic event. There is no consensus on the implications of the swarm for future earthquakes.

Contextual Notes

The discussion highlights the complexity of seismic activity in the region, including the interplay between various geological features and the uncertainty surrounding predictions of larger earthquakes based on smaller seismic events.

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M 4.9 - 4km NE of Westmorland, CA
https://earthquake.usgs.gov/earthquakes/eventpage/ci39641528/executive
  • 2020-10-01 00:31:27 (UTC)
  • 33.056°N 115.590°W
  • 11.5 km depth
M 4.5 - 4km NE of Westmorland, CA
https://earthquake.usgs.gov/earthquakes/eventpage/ci39643328/executive
  • 2020-10-01 03:36:34 (UTC)
  • 33.066°N 115.597°W
  • 5.7 km depth
Hundreds of earthquakes continue to rattle Southern California, USGS says
https://news.yahoo.com/swarm-nearly-30-earthquakes-rocks-005043056.html

https://earthquake.usgs.gov/earthqu...listOnlyShown=true&settings=true&help=missing
 
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Likes   Reactions: davenn
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Is this cause for worry, portends of the BIG one?
 
Not necessarily... but it's complicated... There are three significant faults there, along with a multitude of minor ones; plus the recent quakes appear to have occurred in an active spreading center (Brawley Spreading Center). The Northern boundary of the spreading center is the infamous San Andreas Fault.

Here is a link to a 30pg pamphlet that gives details of the underlying geology.
https://fire.biol.wwu.edu//trent/alles/GeologySaltonTrough.pdf

Cheers,
Tom
 
jedishrfu said:
Is this cause for worry, portends of the BIG one?
The big one is not likely to be preceded by hundreds of smaller quakes that all relieve stress
 

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