Trisha Shetty (Editor)

Earthquake swarm

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Earthquake swarm

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but may be of the order of days, weeks, or months. They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock.

Examples

  • Between February and April 2008 a swarm of 1,000 small magnitude quakes in the United States, referred to as the 2008 Reno earthquakes began in February and ended in November.
  • During the 2011–12 El Hierro eruption. From July 2011 until October 2011, hundreds of small earthquakes were measured. The accumulated energy released by the swarm increased dramatically on 28 September. The swarm was due to the movement of magma beneath the island, and on 9 October indications of a submarine volcanic eruption were detected.
  • Over 500 quakes and aftershocks occurred during a two-week period in February 2008 near Mexicali, along the Cerro Prieto Fault.
  • In 2013, the Santa Cruz Islands experienced a large earthquake swarm with many magnitude 5 and 6 earthquakes occurring in January and February - foreshocks to the 8.0 2013 Solomon Islands earthquake on February 6.
  • In 2014, an area near the California/Oregon/Nevada borders experienced more than 800 small earthquakes over a period of around three months. More than 550 quakes were on magnitude 2.0 or larger.

    • References

    Earthquake swarm Wikipedia
    (Text) CC BY-SA