1946 Dominican Republic earthquake
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 The Septentrional-Oriente fault zone in the Caribbean and across Hispaniola | |
  | |
| UTC time | 1946-08-04 17:51:10 |
|---|---|
| ISC event | 898498 |
| USGS-ANSS | ComCat |
| Local date | August 4, 1946 |
| Local time | 13:51 AST |
| Magnitude | 7.8 Mw 8.1 Ms |
| Depth | 15.0 km (9.3 mi)[1] |
| Epicenter | 19°12′00″N 69°18′58″W / 19.2°N 69.316°W |
| Areas affected | Dominican Republic |
| Max. intensity | MMI IX (Violent)[2] |
| Peak acceleration | 0.4 g (est)[2] |
| Tsunami | Yes |
| Casualties | 1,790 |
The 1946 Dominican Republic earthquake occurred on August 4 at 13:51 AST near Samaná, Dominican Republic. It was the largest earthquake to occur in the instrumental era in the Caribbean. It generated a tsunami that was observed as far as New Jersey. A total of 1,790 deaths were reported.
The Dominican Republic is located on the eastern part of Hispaniola, which is the site of a complex tectonic environment. The North American plate undergoes subduction below the Caribbean plate.[3] In addition, the seismically active strike-slip Septentrional–Oriente fault zone runs through the northern part of the island. It has been estimated that the fault accumulates about 12 millimetres (1.2 cm; 0.47 in) of strain every year.[4] Major earthquakes (M>=7) have occurred in the northeastern Caribbean at least eleven times over the past 250 years, at least five of which have been located on the megathrust.[5]
Earthquake
The earthquake occurred on August 4 at 13:51 AST with an epicenter near the coast of Samaná Province in the northern Dominican Republic. The mainshock measured 7.8 on the moment magnitude scale; 8.1 on the surface-wave magnitude scale,[6] and originated at a depth of 15 km (9.3 mi).[7] It was caused by movement on a northeast-dipping thrust fault striking northwest.
At least 63 aftershocks followed the largest earthquake including a magnitude 7.0 event that struck the coast on August 8.[8][9] These aftershocks were distributed offshore along a west–northwest trending zone measuring 250 by 75 km (155 by 47 mi). Several aftershocks with focal depths greater than 70 km (43 mi) delineate a south or southwest dipping plate that is subducted beneath the region.[9]
A tsunami was generated by the initial earthquake and caused widespread devastation across Hispaniola. The tsunami was observed in much of the Caribbean and the northwestern Atlantic Ocean.[10][11][12][13] Maximum tsunami heights exceeded 5 metres (16 ft) in several locations, with a height of 8 metres (26 ft) observed at Playa Boca Nueva, although it was likely associated with splash-up.[14] A small tsunami was also recorded by tide gauges at San Juan in Puerto Rico, Bermuda and in the United States at Daytona Beach, Florida and Atlantic City, New Jersey.[15] Approximately 1,790 people were killed by the earthquake and tsunami.[16]
