M4.8 Earthquake Strikes Near Santa Barbara: 29 May 2013

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Damage after the 1925 Santa Barbara earthquake. Photo from the online archive of California

Earthquakes in Santa Barbara

Faults such as that which generated today’s earthquake are typically too small and shallow to give rise to major earthquakes: most large earthquakes recorded to date in the Santa Barbara area are associated with major ruptures of the San Andreas and its associated faults.

A historic catalog of earthquakes in the region, however, shows major tremors affecting Santa Barbara in 1812, 1857, 1902, 1925, 1927 and 1978. The largest of these was also California’s largest quake, the 1857 Fort Tejon earthquake, which had a magnitude of M7.9.

Tremors along the faults within the basin have, despite their general seismic quiescence, produced earthquakes of note close to Santa Barbara itself, in 1812, 1925 and 1978.

Today’s California Quake vs. Earlier Tremors

The 1925 event, at M6.8, was one hundred times larger than the tremor of 29 May and released a thousand times as much energy: it caused widespread damage and killed 13 people. The largest quake in this area, however, seems to have occurred in 1812 at a possible magnitude of M7.1 (note that early magnitudes are estimates).

The 1978 earthquake had a magnitude of just M5.1, not much larger than the today’s tremor, suggesting that today’s Santa Barbara earthquake, though small compared with the earthquakes which can be generated within the region as a whole, was nonetheless significant for its locale.

Sources

USGS. Geology of The Santa Barbara Coastal Plain. Accessed 30 May 2013.

USGS. Historic Earthquakes West of Ventura, California in the Santa Barbara Channel  1812 December 21. Accessed 30 May 2013.

USGS. M4.8 – 5km W of Isla Vista, California. (2013). Accessed 30 May 2013.

Yeats, R. Active Faults of the World. Cambridge University Press.

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