1918 Puerto Rico earthquake
Encyclopedia
The San Fermín earthquake, also known as the Puerto Rico earthquake of 1918, was a major earthquake
that struck the island of Puerto Rico
at 10:14am on October 11, 1918. The magnitude for the earthquake has been reported at around 7.5 (or Level IX in the Rossi-Forel scale
used at that time); however, that might not be an exact number. The main-shock epicenter
occurred offshore about 5 km (3.1 mi) from the northwestern coast of the island, somewhere along the Puerto Rico Trench
.
The earthquake triggered a tsunami
with waves measured at approximately 5.5 meters (20 feet) that lashed the west coast of the island and is remembered as one of the worst natural disasters that have struck the island. The losses resulting from the disaster were approximately 116 casualties and $4 million in property.
about 16 km (9.9 mi) from the northwestern coast of the island, somewhere along an old left-lateral strike-slip fault close to the Mona Passage. The strongest ground shaking has been estimated at around a magnitude 7.3 or 7.5, or Level IX (Rossi-Forel scale
).
The resulting tsunami affected primarily the west coast city of the Island (primarily Mayaguez) and other adjacent towns as well.
The earthquake caused several mudslides in areas where the magnitude exceeded Level VII, but none of it was deemed as tragic. Also, the river currents were affected, which, in many cases affected the foundations of many bridges which ended up collapsing.
The reported casualties of the earthquake have been estimated somewhere between 91 to 116 deaths. Approximately 40 of these deaths were caused by the tsunami. Also, damages to property were estimated at around $4 million, which was a huge amount at that time.
lashed the west coast of the island, probably 4–7 minutes after the main shock. The highest waves were measured at 5.5 to 6 meters (20 feet) and ended up destroying several coast-side villages. It has been estimated that 40 people were drowned as a direct result of the tsunami.
The tsunami reached Galveston, Texas
as a disturbance on tide gauges.
s were reported immediately after the main earthquake. On October 24 and November 12, two strong aftershocks were reported in the island. However, no damages were reported as a result.
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
that struck the island of Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
at 10:14am on October 11, 1918. The magnitude for the earthquake has been reported at around 7.5 (or Level IX in the Rossi-Forel scale
Rossi-Forel scale
The Rossi–Forel scale was one of the first seismic scales to reflect earthquake intensities. Developed by Michele Stefano Conte de Rossi of Italy and François-Alphonse Forel of Switzerland in the late 19th century, it was used for about two decades until the introduction of the Mercalli intensity...
used at that time); however, that might not be an exact number. The main-shock epicenter
Epicenter
The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...
occurred offshore about 5 km (3.1 mi) from the northwestern coast of the island, somewhere along the Puerto Rico Trench
Puerto Rico Trench
The Puerto Rico Trench is an oceanic trench located on the boundary between the Caribbean Sea and the Atlantic Ocean. The trench is associated with a complex transition between the subduction zone to the south along the Lesser Antilles island arc and the major transform fault zone or plate boundary...
.
The earthquake triggered a tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
with waves measured at approximately 5.5 meters (20 feet) that lashed the west coast of the island and is remembered as one of the worst natural disasters that have struck the island. The losses resulting from the disaster were approximately 116 casualties and $4 million in property.
Geology of the Earthquake
The epicenter of the 1918 Puerto Rico Earthquake was located in the Mona PassageMona Passage
The Mona Passage 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 Canal....
about 16 km (9.9 mi) from the northwestern coast of the island, somewhere along an old left-lateral strike-slip fault close to the Mona Passage. The strongest ground shaking has been estimated at around a magnitude 7.3 or 7.5, or Level IX (Rossi-Forel scale
Rossi-Forel scale
The Rossi–Forel scale was one of the first seismic scales to reflect earthquake intensities. Developed by Michele Stefano Conte de Rossi of Italy and François-Alphonse Forel of Switzerland in the late 19th century, it was used for about two decades until the introduction of the Mercalli intensity...
).
The resulting tsunami affected primarily the west coast city of the Island (primarily Mayaguez) and other adjacent towns as well.
Immediate Effects
As a result of the earthquake, numerous structures in the west coast suffered irreparable damages. Factories and production centrals were virtually destroyed, while bridges and roads were severely damaged.The earthquake caused several mudslides in areas where the magnitude exceeded Level VII, but none of it was deemed as tragic. Also, the river currents were affected, which, in many cases affected the foundations of many bridges which ended up collapsing.
The reported casualties of the earthquake have been estimated somewhere between 91 to 116 deaths. Approximately 40 of these deaths were caused by the tsunami. Also, damages to property were estimated at around $4 million, which was a huge amount at that time.
Tsunami
As a result of the earthquake, a tsunamiTsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
lashed the west coast of the island, probably 4–7 minutes after the main shock. The highest waves were measured at 5.5 to 6 meters (20 feet) and ended up destroying several coast-side villages. It has been estimated that 40 people were drowned as a direct result of the tsunami.
The tsunami reached Galveston, Texas
Galveston, Texas
Galveston is a coastal city located on Galveston Island in the U.S. state of Texas. , the city had a total population of 47,743 within an area of...
as a disturbance on tide gauges.
Aftershocks
Several aftershockAftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...
s were reported immediately after the main earthquake. On October 24 and November 12, two strong aftershocks were reported in the island. However, no damages were reported as a result.
See also
- Geology of Puerto RicoGeology of Puerto RicoPuerto Rico is composed of Jurassic to Eocene volcanic and plutonic rocks, which are overlain by younger Oligocene to recent carbonates and other sedimentary rocks. Most of the caverns and karst topography on the island occurs in the northern Oligocene to recent carbonates...
- Puerto Rico TrenchPuerto Rico TrenchThe Puerto Rico Trench is an oceanic trench located on the boundary between the Caribbean Sea and the Atlantic Ocean. The trench is associated with a complex transition between the subduction zone to the south along the Lesser Antilles island arc and the major transform fault zone or plate boundary...