A massive earthquake registering 7.6  on the Richter Scale (downgraded from the initial reading of 7.9) has struck along the western edge of Costa Rica, triggering tsunami warnings up and down the rim of Central and South America. The quake struck about 100 km west of the capital city of San Jose at about 8:42 a.m. local time (10:42 Eastern time). It's too soon for reports of damage as of yet, but we'll keep updating you with details as we get them.

According to this map from the U.S. Geological Survey, there have been numerous smaller quakes off the coast of El Salvador and Nicaragua, but along the same fault line that follow the eastern Pacific Rim.

A tsunami warning was briefly and erroneously issued for the Caribbean side of the country, but was quickly canceled. Warnings remain in effect along the Pacific side, as far south as Chile.

UPDATES: As of 11:30 a.m. ET, the latest tsunami bulletin cancels the warnings for all areas except Costa Rica, Panama, and Nicaragua.

11:50 a.m.: The Red Cross in Costa Rica reports no casualties so far. The depth of the quake is listed at around 25 miles, which is deep enough that it might limit severe damage.

12:10 p.m.: There are some damage reports coming in now. This bridge was reportedly knocked out (via BNONews) by the quake and other buildings are showing some cracks and other damage.