Significant Earthquakes on a major fault system in Hispaniola, Puerto Rico, the Virgin Islands, and the Lesser Antilles, 1500–2010: Implications for Seismic Hazard

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Earthquakes have been documented in the northeastern Caribbean since the arrival of Columbus to the Americas; written accounts of these felt earthquakes exist in various parts of the world.  To better understand the earthquake cycle in the Caribbean, the records of earthquakes in earlier catalogs and historical documents from various archives, which are now available online, were critically examined.  We prepared a report “Accounts of Damage from Historical Earthquakes in the Northeastern Caribbean, to Aid in the Determination of their Location and Intensity Magnitudes” (USGS OFR 2011-1133, https://pubs.usgs.gov/of/2011/1133/ ), which updates previous catalogs of earthquakes, in particular earthquakes in Hispaniola, to give to the public the most comprehensive documentation of earthquake damage and to further the understanding of the earthquake cycle in the northeastern Caribbean. 

Documentation of an event in the past depended on the population and political trends of the island. The availability of historical documents is further limited by the digitization schedule, and copyright laws of each archive. Examples of documents accessed are governors’ letters, newspapers, and other circulars published within the Caribbean, North America, and Western Europe.  Key words were used to search for publications that contain eyewitness accounts of various large earthquakes. Finally, this catalog provides descriptions of damage to buildings used in previous studies for the estimation of moment intensity (MI) and location of significantly damaging or felt earthquakes in Hispaniola and in the northeastern Caribbean, all of which have been described in other studies.

Reported damages from the 2010 Haiti earthquake and other digitally-recorded earthquakes were used to derive regional seismic attenuation relationships for Hispaniola and for Puerto Rico and the Virgin Islands. The attenuation relationship for Hispaniola earthquakes and northern Lesser Antilles earthquakes is similar to that for California earthquakes, indicating a relatively rapid attenuation of damage intensity with distance. Intensities in Puerto Rico and the Virgin Islands decrease less rapidly with distance. The intensity assignments and the attenuation relation are then used in a grid search to find source locations and magnitudes for historical earthquakes from 1500 to the early 20th century.

Haiti and Enriquillo Fault

We describe a sequence of devastating earthquakes on the Enriquillo fault system in the eighteenth century. An intensity magnitude MI 6.6 earthquake in 1701 occurred near the location of the 2010 Haiti earthquake, and the accounts of the shaking in the 1701 earthquake are similar to those of the 2010 earthquake. A series of large earthquakes migrating from east to west started with the 18 October 1751 MI 7.4–7.5 earthquake, probably located near the eastern end of the fault in the Dominican Republic, followed by the 21 November 1751 MI 6.6 earthquake near Port-au-Prince, Haiti, and the 3 June 1770 MI 7.5 earthquake west of the 2010 earthquake rupture. The 2010 Haiti earthquake may mark the beginning of a new cycle of large earthquakes on the Enriquillo fault system after 240 years of seismic quiescence. The entire Enriquillo fault system appears to be seismically active; Haiti and the Dominican Republic should prepare for future devastating earthquakes. 

Hispaniola and Septentrional Fault

We speculate that the December 2, 1562 (MI 7.7) and May 7, 1842 (MI 7.6) earthquakes ruptured the Septentrional Fault in northern Hispaniola. If so, the recurrence interval on the central Septentrional Fault is ~300 years, and only 170 years has elapsed since the last event. The recurrence interval of large earthquakes along the Hispaniola subduction segment is likely longer than the historical record. Intra-arc M** ≥ 7.0 earthquakes may occur every 75–100 years in the 410-km-long segment between the Virgin Islands and Guadeloupe

The Caribbean-North America tectonic plate boundary

Large earthquakes (including a 1946 M 8.1 event) occurred in the 20th-century along the Caribbean-North America plate-boundary segment north of the Dominican Republic and east to Mona Passage (NW tip of Puerto Rico), but historical events from this segment were not identified. This is because the recurrence rate of large earthquakes along this segment is probably longer than the time period between the arrival of Columbus and the 20th century. 

The remaining plate boundary from Mona Passage eastward to the Lesser Antilles is probably not associated with M > 8 historical subduction-zone earthquakes. The May 2, 1787 earthquake, previously assigned an M 8–8.25, is probably only MI 6.9 and could be located north, west or SW of Puerto Rico. An MI 6.9 earthquake on July 11, 1785 was probably located north or east of the Virgin Islands.

Historical earthquakes with magnitudes MI < 8 on April 5, 1690, February 8, 1843, and October 8, 1974 were located within the arc in the northern Lesser Antilles, and none has been located with certainty at the subduction zone.

* MI - Magnitude Intensity is the estimated magnitude of an earthquake based on documented felt and damage descriptions for each earthquake and using a known model of seismic attenuation for this region.

** M – A bold M is the moment magnitude of an earthquake calculated from instruments. 

 

Topographic and bathymetric map of the island of Hispaniola.

Map of the island of Hispaniola that include the countries of Haiti and the Dominican Republic. Fault traces are shown as lines with the following descriptions: barbed=thrust fault; solid=strike-slip fault with arrows showing relative direction of motion; black and white=normal fault. The arrow at the top right corner shows the direction of the North American plate motion relative to the Caribbean plate. The intensity centers of historical events on or near the Enriquillo fault are shown as orange stars. The epicenter of the 2010 mainshock is shown as a white star. The zone of 2010 aftershocks, and the presumed rupture of the 2010 mainshock, is located along the Enriquillo fault from the white star to the 1701 earthquake orange star. The small green circles are the locations of towns mentioned in the text: A=Old Azua; AaV=Anse a Veau; C=Cotui; CdS=Cul-de-Sac; CH=Cap Haitien; H=Hinche; L=Leogane; LC=Les Cayes; LV=La Vega; PaP=Port-au-Prince; PG=Petit Goave; SD=Santo Domingo. 

 

Topography and bathymetry map of the Northeastern Caribbean.

Map of the Northeastern Caribbean: topography is in shades of green and bathymetry in shades of blue. Fault traces are shown as lines with the following descriptions: barbed=thrust fault; solid=strike-slip fault with arrows showing relative direction of motion; black and white=normal fault. Faults outlined in red have a potential to generate a large earthquake. The arrow at the top right corner shows the direction of the North American plate motion relative to the Caribbean plate. All red stars with a date before the 20th century show the intensity center (MI) for that earthquake. The red star with a red ellipse shows the general location of several 17th century earthquakes with sparse felt data. Stars with 20th and 21st century years are earthquake epicenters located using instrument data. Years in boxes next to red outlines are reoccurrence rates. Red question marks indicate unknown reoccurrence rates for those respective faults. Those parts of the subduction zone not outlined by red are not expected from this study to generate large earthquakes