Earthquake History of Puerto Rico

Four strong earthquakes have affected Puerto Rico since the beginning of its colonization. The most recent of these occurred on October 11, 1918. The epicenter was located northwest of Aguadilla in the Mona Canyon (between Puerto Rico and the Dominican Republic). This earthquake had an approximate magnitude of 7.5 on the Richter scale and was accompanied by a tsunami ("tidal" wave) which got up to 6 meters (19.5 feet) high. Damage was concentrated in the western area of the Island because this was the closest zone to the earthquake. The earthquake killed about 116 people and caused more than 4 million dollars of damage. Numerous houses, factories, public buildings, chimneys, bridges and other structures suffered severe damage.

On November 18, 1867, 20 days after the Island was devastated by Hurricane San Narciso, a strong earthquake occurred with an approximate magnitude of 7.5 on the Richter Scale. The epicenter was located in the Anegada Passage, between Puerto Rico and St. Croix, Virgin Islands. The earthquake produced a tsunami that ran inland almost 150 meters (490 feet) in the low parts of the coast of Yabucoa. This quake caused damage in numerous buildings on the Island, especially in the eastern zone.

Possibly the strongest earthquake that has affected Puerto Rico since the beginning of colonization occurred on May 2, 1787. This was felt strongly throughout the Island and may have been as large as magnitude 8.0 on the Richter Scale. Its epicenter was possibly to the north, in the Puerto Rico Trench. The quake was felt very strongly all across the Island. It demolished the Arecibo church along with the El Rosario and La Concepcion monasteries and damaged the churches at Bayamon, Toa Baja and Mayaguez. It also caused considerable damage to the castles of San Felipe del Morro and San Cristobal, breaking cisterns, walls and guard houses.

The other strong earthquake, whose magnitude has not been determined, occurred in 1670, significantly affecting the area of San German District.

Translated from "Terremoto," written by Jose Molinelli Freytes, Puerto Rico Civil Defense, under the auspices of the Federal Emergency Management Agency (FEMA).