Strong Magnitude 5.1 earthquake strikes the Costa Rica coast

Earthquake Report comment :
The (preliminary) epicenter of the earthquake is located just outside Puntarenas, the cruise terminal city.
The earthquake hypocenter was at a shallow depth of 25 km.
The area is well known by tourists visiting the Reserva Biologica Guayabo in the Gulf of Nicoya.
The Gulf of Nicoya (Spanish: Golfo de Nicoya) is an inlet of the Pacific Ocean. It separates the Nicoya Peninsula from the mainland of Costa Rica, and encompasses a marine and coastal landscape of wetlands, rocky islands and cliffs.
On the detailed satellite view it can be seen that the epicenter (if confirmed) is right under the beaches of Islas Negritos.
Costa Rica is used to moderate earthquakes.

National press in Costa Rica talks about a 5.3 magnitude (their source : Observatorio Vulcanológico y Sismológico de Costa Rica) and the depth calculated by the Costa Ricans is even more shallow at 15 km.
The current epicenter area is active almost all year long.
The quake originates from the Cocos plate who is subducting below the Costa Rica mainland.
Within half an hour after the first shock, the authorities have at least registered 20 aftershocks.
Read the comments from people who felt the earthquake (nacion - spanish)

Seismograph from Peninsula de Nicoya from September 16

Most important Earthquake Data:
Magnitude : Mb 5.1
Thursday, September 16, 2010 at 09:27:26 AM at epicenter
Depth (Hypocenter) : 25 km
Geo-location(s) :
15 km (10 miles) SSW of Puntarenas, Costa Rica
85 km (55 miles) W of SAN JOSE, Costa Rica

Links to important maps
USGS Did You Feel It Map
Google satellite map of the area showing the kind of terrain the earthquake took place
USGS historic earthquakes map

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