1787 Boricua earthquake facts for kids

The 1787 Boricua earthquake shook the island of Puerto Rico on May 2. Scientists first thought this earthquake was very strong, around 8.0–8.5 on the Richter scale. However, newer information suggests it was closer to 6.9. The place where the earthquake started, called the epicenter, was likely north of Puerto Rico. It was probably in the deep Puerto Rico Trench. One expert, José Molinelli, calls it the "strongest" earthquake in Puerto Rico's history.

What Happened During the Earthquake?

Many people felt the earthquake all over the island. It caused a lot of damage to buildings. For example, the church in Arecibo was destroyed. Monasteries like El Rosario and La Concepcion also fell apart.

Other churches were damaged too. This includes churches in Bayamon, Toa Baja, and Mayagüez. Important forts, like San Felipe del Morro and San Cristobal, also suffered. Their walls, water tanks, and guard houses broke.

The southern part of the island did not seem to have major damage. But the walls of the Our Lady of Guadalupe church in Ponce did crack. There are no old records of damage on nearby islands. This makes experts think the earthquake was not as big as first believed.

How Do We Know About This Earthquake?

There are not many old written records about this earthquake. But some clues tell us what happened. For example, the earthquake changed the shape of the ocean floor.

Also, scientists found special soil layers. These layers show that the earthquake changed the island itself. It seems that parts of the island may have sunk about 3 meters (almost 10 feet).

The earthquake also caused a tsunami. This was a huge ocean wave. It might have been 40 to 60 feet high. This is because the Caribbean Sea is not very deep in some places. The tsunami flooded coastal areas of Puerto Rico. It left a thin layer of ocean salt and sand. This layer shows that the saltwater reached almost 2 miles inland.