SIGNIFICANT EARTHQUAKES IN THE PUERTO RICO ZONE*
* September 8, 1615: Earthquake in the Dominican Republic that caused damages in Puerto Rico (A).
* August 15, 1670: Damages in San Germán and San Juan (MJ).
* 1717: Church San Felipe in Arecibo and the parochial house in San Germán were destroyed (A).
* August 30, 1740: The Church of Guadalupe in Villa de Ponce was destroyed (A). Intensity VII, there is only information from Ponce that the earthquake was felt, absence of information of San Germán and the information of Yauco and Lajas suggest a superficial earthquake near to Ponce (G).
* May 2, 1787: A strong earthquake was felt in the whole island; damages were reported in all places, except in the South. In the islet of San Juan there were considerable damages and several structures collapsed (DH, according to information of the Town hall of San Juan, 1787). The walls of the Guadalupe Church in Ponce were cracked (G).
* April 16, 1844, 9:20am: The epicenter was located to the north of the island and felt in Puerto Rico (VII-VIII, (RF)) and Saint Thomas. Several buildings collapsed and cracked. A tower of the Church of Isabela was cracked. It was felt for about 30 seconds (RT). In San Juan almost all the stone houses were cracked @ (Barbadian Newspaper, May 25 of 1844). Intensity of VII in San Juan (SL).
* April 20, 1824, 3:00am: Strong earthquake in Saint Thomas, a building was destroyed (RT).
* May 5, 1844: A strong earthquake was felt in Ponce. It was accompanied by a strong underground noise; a terrible earthquake for the island (G). Asencio (1980) also includes it in its listing (it puts 3 references). Note: Since the different catalogues talk about to the tremor of April 16 or May 5, with the exception of MJ that question the one of the 5 of May, it can be that it only happened one of these tremors.
* November 28, 1846, 5:00pm: Felted in all the island, more force and damages in the northwest with maximum intensity of VII (RF). Origin probably in the Passage of Mona (RT).
* February 22, 1851: The walls of the Mayoralty of San Juan were cracked (RT).
* December 14, 1855, 8:15am: Salinas VI and Aguas Buenas V (RF). One says that it is the stronger tremor felt in Salinas. Origin probably to the south of the island (RT). Díaz Hernández reported it like of the 4 of February of 1855.
* October 23, 1860: Strong earthquake with some damages in Mayagüez, Intensity VI-VII (RT).
* May 12, 1865, 9:30am: Two strong tremors in Saint Thomas, the second caused damages (RT).
* August 30, 1865: Churches in Manatí and Ponce were cracked. The origin could have been the center of the island. Intensity of VI (RF) (RT). It happened at night, origin probably in the central part of the island and deep (50-100 km) (G).
* November 18, 1867, 2:50pm: The epicenter of this earthquake was located between Saint Thomas and Saint Croix in the Virgin Islands, M=7.3 (PS). It produced great damages in the Virgin Islands and Puerto Rico by the acceleration of the ground and tsunami. Reid and Taber assigned an intensity equivalent from VIII to IX to this earthquake. This tremor was felt strong in all Puerto Rico, but the most severe effects were in the Eastern part. A strong tsunami was observed for this earthquake, especially in the Virgin Islands, its height was considered in about twenty feet. Tsunami was observed throughout the coasts of the east and the south of Puerto Rico. Observations of peak altitudes for the waves in Puerto Rico went of three on five feet, in nearness of Arroyo, the south eastern coast. Although to this earthquake a higher intensity equivalent to VIII to IX was assigned by Reid and Taber. Robson proposed that this earthquake had an intensity of VIII. It had more than 500 aftershocks during a period of six to seven months (PRWRA). In Ponce, 70 of the 80 chimneys of the sugar refinery fell down (intensity MM = VI; SL).
* December 1, 1867: Three aftershocks of the earthquake of November 18, intensity VII-VIII (RF). Additional damages in Puerto Rico and Virgin Islands (RT).
* March 17, 1868, 6:45am: Greater aftershock of the earthquake of the 18 of November of 1867. It happened to 30 miles to the southwest of the original epicenter. Smaller damages mainly in the Eastern part of the Island of Puerto Rico (PRWRA). Intensity, RG of VII - VIII (RT).
* September 17, 1869, 3:00pm: Earthquake in Saint Thomas almost equal strong as the one of November 18, 1867 (RT).
* August 26, 1874, 6:15am: Strong tremor (V-VI) registered in Puerto Rico (in the morning). Informs of destroyed houses (DH) were received. In San Juan, the vibration lasted two minutes, the houses moved of side to side, the habitants were alarmed, did not report victims, intensity of VI (SL).
* December 8, 1875, night: Apparently an earthquake happened near Arecibo. Few damages were reported, except in a church that suffered enough. Originally was assigned with an intensity of VII-VIII (RF), but Reid and Taber concluded that it is too much high, because damage in only a site was reported (PRWRA). In Ponce was felt with great force, center surely in the island between 50-100 km (G).
* August 15, 1890 1:45am: A violent earthquake was reported from different towns from the island. In Arecibo the bells of the church peal and in Ponce the municipal jail suffered damages (DH). In Ponce the event lasted about 8 to 10 seconds (G).
* May 13, 1902: Felted very strong (V-VI in Saint Thomas) (RT).
* September 27, 1906, 10:41am: The epicenter of this earthquake was considered about 50 Km to the north of the island. The maximum intensity was of VI in San Juan where cracks in the Cathedral and many houses were observed. The intensity in the rest of the island was of IV - V. Tsunami was not reported. It was felt from Santo Domingo (Dominican Republic) to Saint Thomas, a distance of 500 km (RT). In addition to San Juan, other towns reported damages (DH).
* October 20, 1906, 4:10pm: Felted in almost all the island. IV-VI (RF) reported from San Juan and Las Cruces (PRWRA; DH; RT).
* August 4, 1908, 6:20am: Strong earthquake (VI, (RF) in Ponce where there were some damages, also felt in Alto de la Bandera, Yauco, Arecibo and San Germán (RT). Origin probably in the south-center area of the island (G).
* August 13, 1908, 4:07am: Strong Earthquake felt in Ponce, the Post Office’s Building suffered damages. It had a vertical movement, very rare in this zone. Felted lightly in Carmelita. Origin probably near Ponce (RT).
* February 17, 1909, 2:50am: Tremor felt in the Virgin Islands and almost all Puerto Rico. In Saint Thomas and Culebra an intensity of up to VI (RF); 90 Km NE of Vieques (RT).
* October 11, 1918, 10:14am: The epicenter was located about 35 km to the Northwest of Aguadilla, PR in the Mona’s Canyon. Magnitude of 7.3 (PS). Reid and Taber assigned a maximum intensity of IX (equivalent to VIII - IX in MM) in the western part of the island and of V - VI in Guayama. This earthquake generated tsunami that reached 20 feet in Punta Agujereada (8 people reported themselves like drowned), 12 feet in Aguadilla (32 people died drowned), 5 feet in Mayagüez (116 people died because of the earthquake, including the 40 victims of the tsunami). The losses by damages to the property were considered in more than $4,000,000 (RT). By several months they were continued feeling aftershocks of this earthquake, strongest being those of the 24 of October and 12 of November.
* October 24, 1918, 11:43pm: Aftershock of the earthquake of the 11 of October. Maximum intensity in the island was VII (RF).
* November 12, 1918, 5:45pm: Another aftershock of the earthquake of the 11 of October. Maximum intensity in the island was VI (RF, RT).
* February 10, 1920, 6:07pm: Earthquake felt in all Puerto Rico. Maximum intensity was VI (DH), M=6.5.
* December 18, 1922, 8:35am: Earthquake felt in all Puerto Rico. Maximum intensity in the island was VI (DH), M=6.3.
* June 12, 1939 12:05am: Earthquake felt in the entire island. Maximum intensity of VI (DH).
* July 28, 1943, 11:02pm: It happened to the Northwest of Puerto Rico. Its magnitude was of 7.5 (PS). It was felt by many people around Puerto Rico, but it did not cause damages.
* August 4, 1946, 1:51pm: This earthquake of magnitude 7.8 (PS) happened outside the northeastern coast of the Dominican Republic. Ample damages and tsunami were reported in Haiti and the Dominican Republic. This earthquake was felt with an intensity of up to VI in the Mona Island and the western coast of Puerto Rico. In the rest of the island an intensity of V was reported. A tsunami of 2 feet was observed in the western and north coast of the island (PRWRA). Smaller damages in all Puerto Rico were reported (DH).
* August 8, 1946, 9:28am: Earthquake in Dominican Republic (M=7.4, PS). Small tsunami in Mayagüez and Aguadilla.
* March 23, 1979 3:33pm: Strong earthquake felt in all the Caribbean area; in Puerto Rico it was felt with an intensity of VI. It was reported in Haiti, Colombia, Venezuela and Dominican Republic (DH). Epicenter located in the south of the Dominican Republic, 17.89N, 68.97W, and 73 km of depth, M=6.1 (USGS).
* August 24, 1981 5:50am: Strong earthquake felt in all Puerto Rico, M=5.7. Epicenter in the Mona Passage. There were only light damages in Guayanilla (DH).
* May 30, 1987 1:55pm: Strong earthquake felt in the southwest of the island, M=4.6, intensity VI. Epicenter near Boquerón. There were light damages (USGS).
* All hours are local. M is the magnitude that reflects the energy released by the earthquake. If it is not specified that the intensity is RF (Rossi Forell), it is MM (Modified Mercalli).
A - Asencio, E., 1980. Western Puerto Rico Seismicity, USGS OFR 80-192, 135pp.
DH - Díaz Hernández, L.E., 1985. Temblores y Terremotos de Puerto Rico, Ponce, PR.
G - Geomatrix, 1988. Draft Report, Geological - Seismological Evaluation to Assess Potential Earthquake Ground Motions for the Portugués Dam, Puerto Rico, San Francisco.
MJ - McCann, W. y R. Jiménez, 1989. Informe Técnico Final de Investigación de la vulnerabilidad sísmica de Puerto Rico: Aspectos de Sismología e Ingeniería, @ USGS, No. 14-08-000-G1511.
PS - Pacheco, J. y L.R. Sykes, 1992. Seismic moment catalog of large shallow earthquakes, 1900 to 1989, BSSA, Vol. 82, No. 3, pp. 1306-1349.
PRWRA - Puerto Rico Water Resources Authority, 1970. Preliminary Facility Description and Safety Report, Aguirre Nuclear Power Plant, Unit. No. 1, App. A, Part III, Seismicity Investigation, Weston Geophysical Research.
RT - Reid, H.F. y L. Taber, 1919. The Porto Rico Earthquake of 1918 with descriptions of earlier earthquakes report of the Earthquake Investigation Commission, Document No. 269, U.S. House of Representatives, 66th Congress, 1st Session.
SL - Shepherd, J.B. y L.L. Lynch, 1992. An earthquake catalogue for the Caribbean Part I, the pre-instrumental period 1502-1900. Informe presentado a la reunión del Comité Ejecutivo del Programa Latinoamericano y Caribeño de Vulnerabilidad Sísmica, 59pp.
USGS - United States Geological Survey. Preliminary Determination of Epicenters.