M 7.7 - 123 km NNW of Lucea, Jamaica

  • 2020-01-28 19:10:24 (UTC)
  • 19.419°N 78.756°W
  • 14.9 km depth

Tectonic Summary

The January 28, 2020, M 7.7 earthquake in the Caribbean Sea to the south of Cuba and northwest of Jamaica occurred as the result of strike-slip faulting on the plate boundary between the North America and Caribbean tectonic plates. Preliminary focal mechanism solutions for the earthquake indicate slip occurred as the result of left-lateral motion on a steep fault striking towards the east-northeast, or as the result of right-lateral motion on a steep fault striking towards the south-southeast. The fault plane striking approximately east-west is consistent with the orientation of the regional plate boundary; this transform structure is named the Oriente Fault. At the location of this earthquake, the North America plate moves to the west-southwest with respect to the Caribbean plate at a rate of approximately 19 mm/yr.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Strike-slip-faulting events of the size of the January 28, 2020, earthquake are typically about 170x25 km (length x width); modeling of this earthquake implies dimensions of about 200x20 km, predominantly west of the hypocenter.

Five other earthquakes of M 6 or larger have occurred within 400 km of the January 28, 2020 event over the preceding half century. These include a M 6.8 earthquake in December 2004, 280 km to the west of today’s earthquake, and a M 6.2 event in May 1992, almost 100 km to the east of today’s quake. Likely because of their location away from land and major population centers, none of these earthquakes are known to have resulted in shaking-related damage or fatalities.

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