The 1918 San Fermín earthquake, also known as the Puerto Rico earthquake of 1918, struck the island of

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...

at on October 11. The earthquake measured 7.1 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

and IX (''Violent'') on the Mercalli intensity scale. The mainshock

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

occurred off the northwestern coast of the island, somewhere along the

Puerto Rico Trench The Puerto Rico Trench is located on the boundary between the Caribbean Sea and the Atlantic Ocean. The oceanic trench, the deepest in the Atlantic, is associated with a complex transition between the Lesser Antilles subduction zone to the sou ...

. The earthquake triggered a

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

with waves measured that swept the west coast of the island. The combined effects of the earthquake and tsunami made it one of the worst natural disasters that have struck the island. The losses resulting from the disaster were approximately 76–118 casualties and $4–29 million in property damage.

Earthquake

The epicenter of the 1918 San Fermín earthquake was located in the

Mona Passage The Mona Passage ( es, Canal de la Mona) is a strait that separates the islands of Hispaniola and Puerto Rico. The Mona Passage connects the Atlantic Ocean to the Caribbean Sea and is an important shipping route between the Atlantic and the Panama ...

off the northwestern coast of the island. The strongest ground shaking has been estimated at intensity IX on the Mercalli intensity scale. The resulting tsunami affected primarily the west coast towns of the island (primarily Mayaguez).

Damage

Numerous structures in the west coast suffered irreparable damage. Factories and production facilities were virtually destroyed, while bridges and roads were severely damaged. The earthquake caused several mudslides in areas where the intensity exceeded Level VII, but none caused numerous deaths. Also, the river currents were affected, which, in many cases affected the foundations of many bridges, resulting in their collapse. Telegraph cables under the ocean were damaged, cutting off the island from outside communication for a time. The reported

casualties A casualty, as a term in military usage, is a person in military service, combatant or non-combatant, who becomes unavailable for duty due to any of several circumstances, including death, injury, illness, capture or desertion. In civilian usag ...

of the earthquake have been estimated somewhere between 76 and 116 deaths. Approximately 40 of these deaths were caused by the tsunami which swept shore communities. Damage to property was estimated to be between $4 and 29 million. In Mayagüez, the largest city affected, 700 masonry buildings were damaged and 1,000 wooden houses, so many people were homeless. Major buildings like the church, post office and hall were severely damaged. With fear because of the aftershocks, many people camped out in the hills for weeks.Peter Aviles, "The Earthquake of the Century"
2002, hosted at University of Puerto Rico, accessed 24 October 2013

Tsunami

As a result of the earthquake, a

lashed the west coast of the island, probably 4–7 minutes after the main shock. The highest waves were estimated at in Point Agujereada, at Point Borinquen, and at Point Jiguero. Several coastal villages were destroyed and it has been estimated that 40 people drowned (32 in Aguadilla alone) as a direct result of the tsunami.

Aftershocks

Several aftershocks were reported immediately after the main earthquake. On October 24 and November 12, two strong aftershocks were reported on the island. However, no damage was reported as a result.

United States response

The response from the United States was to exempt the municipalities most affected from paying taxes for a short period immediately following the quake: those municipalities were Mayagüez, Aguada,

Aguadilla Aguadilla (, ), founded in 1775 by Luis de Córdova, is a city and municipality located in the northwestern tip of Puerto Rico, bordered by the Atlantic Ocean to the north and west, north of Aguada, and Moca and west of Isabela. Aguadilla i ...

, Añasco and Isabela. The U.S. appropriated funds for the repair of municipal buildings of the most affected municipalities.

Gallery

File:Iglesia Mayaguez 1918.jpg, Cathedral of Mayagüez after the first earthquake; further damage toppled the left tower File:Terremoto-pr-2.gif, Destroyed brick homes in Mayagüez File:Epicenters of earthquakes around Puerto Rico in last 100 years.jpg, Map showing the epicenters of all the magnitude 5 and greater earthquakes around Puerto Rico for the last 100 years File:Aguadilla Punta Borinquen Lighthouse Ruins.jpg, Aguadilla Punta Borinquen Lighthouse Ruins—an 1889 lighthouse destroyed by the tsunami

References

Sources * * *

External links

"Puerto Rico Seismic Network"
– University of Puerto Rico, Mayaguez
Significant earthquake – Puerto Rico: Mona Passage
–

National Geophysical Data Center The United States National Geophysical Data Center (NGDC) provided scientific stewardship, products and services for geophysical data describing the solid earth, marine, and solar-terrestrial environment, as well as earth observations from spac ...

M 7.1 - Puerto Rico region
–

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

The Tectonic Setting and Geology of Puerto Rico and Its Surrounding Seafloor
–

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

Map of Tsunami wave heights in Puerto Rico by USC Tsunami Research Group

Wave transformation in Coastal Wiki

Earthquakes and Tsunamis in Puerto Rico and the U.S. Virgin Islands by USGS.gov
* {{DEFAULTSORT:1918 San Fermín earthquake Mayagüez, Puerto Rico San Fermin Earthquake, 1918 San Fermin Earthquake, 1918 1918 tsunamis Earthquakes in Puerto Rico