History of Puerto Rico Earthquakes

The tragedy that is currently unfolding in Haiti from the recent devastating 7.0 magnitude earthquake got me thinking about earthquakes here in Puerto Rico. The image above represents the earthquake activity for the past seven days here in Puerto Rico (roughly Jan 8 – 15, 2010) as you can see there are quite a few recorded; in fact the Puerto Rico Seismic Network has registered around 80 earthquake tremors in the first 15 days of 2010. Thankfully, for Puerto Rico these are usually on the lower end of the scale, but people do feel them around the island. In fact since being here I have actually felt two earthquakes, one of which was the 7.4 magnitude Martinique earthquake back in November 2007.

So what about major earthquakes in Puerto Rico?

According to the U.S Geological Survey there have been FOUR strong earthquakes that have affected Puerto Rico since it was first colonized: 1670, 1787, 1867, and 1918.

October 11, 1918 – 7.5 magnitude (Richter Scale)

This is the most recent earthquake to hit the island of Puerto Rico. The 7.5 quake was located northwest of Aguadilla in the Mona Canyon (between Puerto Rico and Dominican Republic) creating a tsunami that produced waves up to 19.5 feet (6m) high. Reports indicate that the sea withdrew exposing never before seen reefs and ocean floor before the tsunami hit.

Areas around the western area were damaged and records show 116 people were killed. Two towns on the west coast Aguada and Anasco and were badly affected by this earthquake. In Aguada brick buildings were mostly destroyed (those that survived the initial quake were subsequently destroyed by the aftershock on October 24). The towns church built in 1876 was totally destroyed. It was a similar scenario in Aguada. In total the earthquake caused $4M worth of damage and the loss of 116 lives

See here for a more detailed account and view more images here

November 18, 1867 – 7.5 magnitude (Richter Scale)

This earthquake hit 20 days after the island was hit by Hurricane San Narciso (flooding from this hurricane left 211 people dead). The earthquakes epicenter was located on the east coast in the Anegada Passage (between Puerto Rico and St Croix). This quake also produced a tsunami that flooded low lying areas around the coast near Yabucoa. Reports indicated that just before the tsunami hit the sea withdrew up to 150 meters before the waves returned and flooding the surrounding areas. The eastern part of the island suffered the major damage from this earthquake with the church in Fajardo being completely destroyed and in Guayama the church was badly damaged.

May 2, 1787 – 8.0 magnitude (Richter Scale)

Records on this earthquake appear to be limited, with the epicenter reported to be to the north in the Puerto Rico Trench. The whole island felt this earthquake that resulted in damage around the island, including El Morro and San Cristobel forts. Other buildings destroyed or damaged included: Arecibo church, El Rosario and La Concepcion monasteries and churches in Bayamon, Toa Baja and Mayaguez.