The seabed of the Cayman Trough is flat at the segment (80.0W and 17.7N to 78.5W and 19.5N). The Puerto Rico Trench is the deepest part of the Atlantic Ocean, with water depths exceeding 8,300 meters. The free-air minimum east of the Lesser Antilles is related to underthrusting of the Caribbean plate by the Atlantic Ocean plate. A tsunami killed 40 people in NW Puerto Rico following a magnitude 7.3 earthquake in 1918. (2011), Significant earthquakes on the Enriquillo fault system, Hispaniola, 1500-2010: Implications for seismic hazard, Geomorphic and stratigraphic evidence for an unusual tsunami or storm a few centuries ago at Anegada, British Virgin Islands, Inland fields of dispersed cobbles and boulders as evidence for a tsunami on Anegada, British Virgin Islands, Pacific Coastal and Marine Science Center. Images of the slope north of Puerto Rico disclose massive slope failure scars, as much as 50 km across, that probably generated tsunamis along the north shore of the island. The rapid (14-40 kyr) and uniform tilt along a 250 km long section of the trench is compatible with scales of mantle flow and plate bending. [27], At scales between entire mountain ranges and ore bodies, Bouguer anomalies may indicate rock types. The Puerto Rico Trench, in contrast, is located at a boundary between two plates that slide past each other with only a small component of subduction. Agreement NNX16AC86A, Journal of Geophysical Research (Solid Earth), Is ADS down? It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. The complex dates in part from the Eocene, and elements of the arc system. You do not have access to this content, please speak to your institutional administrator if you feel you should have access. In both of these cases the driving mass has an optimum depth of about 100 km. Res., 64, 1545. Leg 3 will include telepresence capability for all ROV dives, permitting the public to watch the expedition live and in action over the Internet. Richter was equipped with a highly precise pendulum clock which had been carefully calibrated at Paris before his departure. Some reports indicate that nearly 1,800 people drowned. Trenches in the Pacific are located in places where one tectonic plate subducts or slides under another one. This brings the free-air anomaly, which omits the correction terms for either, close to zero. Fifteen years later, Isaac Newton used his newly formulated universal theory of gravitation to explain the anomaly. There are no active volcanoes in Puerto Rico and virgin islands. Immediately after the 1946 earthquake, a tsunami struck northeastern Hispaniola and moved inland for several kilometers. ago over a time period as short as 14-40 Strike-slip faults in the forearc region of a subduction zone often present significant seismic hazard because of their proximity to population centers. Uri ten Brink, Chief Scientist . A study of the seismic velocity structure of the subcrustal oceanic lithosphere was conducted in the western North Atlantic north of the Lesser Antilles, where the age of the lithosphere, We infer from the bathymetry and gravity field and from the source mechanisms and depths of the eight largest earthquakes in the Bali region that the Bali Basin is a downwarp in the crust of the, Abstract Velocity modeling and earthquake relocation are used to examine the structure and seismicity of an area south of the Puerto Rico trench in the northeast Caribbean, and to explore whether and, We have determined focal mechanisms for the largest earthquake (Ms = 7.8) recorded instrumentally in the Caribbean Basin, the August 4, 1946, Hispaniola earthquake, and three of its large-magnitude, The direction and rate of movement of the Caribbean plate with respect to North America are determined from the slip vectors of shallow earthquakes and from the configuration of downgoing seismic, We have developed two-dimensional spherical shell finite element models of elastic displacements in the North America-Caribbean (NA-Ca) plate boundary zone (PBZ) in order to quantify crust and fault. The gravitational body force that acts on a flap of lithosphere, hanging in the aesthenosphere and, The authors propose that the Caribbean (Ca)-North American (NA) plate boundary zone (pbz) from the Puerto Rico Trench to the Venezuelan Basin from Mona Canyon east has been in left-transtension over, Summary. Report an Error, Site Index The unusually deep sea floor is not limited to the trench, but also extends farther south toward Puerto Rico. The free-air anomaly is around +70 mgal along the Andes coast, and this is attributed to the subducting dense slab. subducts, or slides, under another one. The gravitational body force that acts on a flap of lithosphere, hanging in the aesthenosphere and more dense than it, pulls the lithosphere down at the trench. 5, Puerto Rico Trench negative gravity anomaly belt, The Caribbean: gravity field and plate tectonics, Geophysical investigation of the Puerto Rico Trench and outer ridge, Seismic refraction and reflection measurementsPuerto Rico outer ridge, Continuous seismic profiles of the outer ridge and Nares basin north of Puerto Rico, Geophysical study of Antilles outer ridge, Puerto Rico trench, and northeast margin of Caribbean Sea, On the applicability of a universal elastic trench profile, Seismic refraction and reflection in Caribbean Sea, Crustal and upper mantle structure of the Central Aleutian Arc, Evidence for high density crust and mantle beneath the Chile trench due to the descending lithosphere, The Kuril Trench-Hokkaido Rise system: Large shallow earthquakes and simple model of deformation, The present day motions of the Caribbean plate, Paleogeography and geologic history of Greater Antilles, The relationship between bathymetry and gravity in the Atlantic Ocean, Tectonics of the Caribbean and Middle America regions from focal mechanisms and seismicity, Gravity anomalies and convection currents 1. Finally, a thick limestone platform, which was originally deposited in flat layers near sea level, is now tilted northward at a uniform angle. Other margins of the island (west, south, and south west) are also associated with massive tectonic features and may pose addtional hazard. The Caribbean plate is roughly rectangular, and it slides eastward at about 2 cm/yr relative to the North American plate. For a measurement point above the reference ellipsoid, this means that the gravitational attraction of the bulk mass of the earth is slightly reduced. The M7.0 2010 Haiti earthquake epicenter was located on land 27 km north of the Caribbean Sea and its focal mechanism was oblique strike-slip. [11], The remaining gravity anomaly at this point in the reduction is called the free-air anomaly. The overwash, after crossing a fringing coral reef and 1.5 km of shallow subtidal flats, cut dozens of breaches through sandy beach ridges, deposited a sheet of sand and shell capped with lime mud, and created inland fields of cobbles and boulders. Careful analysis of the gravity data allows geologists to make inferences about the subsurface geology. Figure 3. [8], The local topography of the land surface affects the gravity measurement. Download image (jpg, 44 KB). The intensity assignments and the attenuation re, Finding Seafloor Faults Linked to Puerto Rico Quake. The crustal thickness and the free-air anomaly computed for sinkers of different sizes and depths are then compared with the measured freeair anomalies and seismic depths of the Puerto Rico trench and the mid-Atlantic rise. the Puerto Rico Trench is also characterized by the most negative free-air gravity anomaly on Earth,-380 mGal, located 50 km south of the trench, where water depth is 7950 m (Fig ure 2). The increased dip could have been caused by shearing or even by a complete tear of the descending North American slab, although the exact nature of this deformation is unknown. Two-thirds of this is from the Moon. Figure 4. Large tsunamis have also hit Puerto Rico and Hispaniola, reportedly killing 1800 people in 1946 and 40 people in 1918. However, the Earth has a rugged surface and non-uniform composition, which distorts its gravitational field. Tectonophysics: Dynamics of lithosphere and mantle: general (1213); Tectonophysics: Dynamics: gravity and tectonics; Tectonophysics: Subduction zone processes (1031; Marine Geology and Geophysics: Subduction zone processes (1031; Geodesy and Gravity: Gravity anomalies and Earth structure (0920. Thesis (Sc.D.) Figure 1. The Puerto Rico trench negative free-air gravity anomaly belt extends from south of Barbados, around the Antillean arc, to eastern Cuba. Bathymetry of the northeast corner of the Caribbean plate. The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Share sensitive information only on official, secure websites. Sharing - Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in other subsequent works and to make unlimited photocopies of items in this journal for noncommercial use in classrooms to further education and science. [10], The next correction is the free-air correction. During Leg 3, encompassing most of the month of April, scientists will be exploring the U.S. The Puerto Rico trench exhibits great water depth, an extremely low gravity anomaly, and a tilted carbonate platform between (reconstructed) elevations of +1300 m and -4000 m. I argue that these features are manifestations of large vertical movements of a segment of the Puerto Rico trench, its forearc, and the island of Puerto Rico that took place 3.3 m.y. The region has high seismicity and large earthquakes (figure 2). Click image for larger view and image credit. In contrast, on its eastern boundary, the Caribbean overrides the North American plate, creating the island arc of the Lesser Antilles with its active volcanoes. Numerical simulation of the 1918 Puerto Rico tsunami showing calculated inundation of the Aguadilla coast in northwest Puerto Rico. Agreement NNX16AC86A, Is ADS down? Location of earthquakes as a function of depth and size in the northeastern Caribbean. Transit line down to Puerto Rico (red line) and two survey area boxes within the region around Puerto Rico and the U.S. Virgin Islands. Approximate operating area (white polygons) of NOAA Ship Okeanos Explorer during Leg 3. ago over a time period as short as 14-40 kyr. This comparison, though of limited application to other places, helps calibrate coastal geology for assessment of earthquake and tsunami potential along the Antilles Subduction Zone. For example, the northeast-southwest trending high across central New Jersey represents a graben of Triassic age largely filled with dense basalts. I explain these vertical movements by a sudden increase in the slab's descent angle that caused the trench to subside and the island to rise. An official website of the United States government. To explore along with the expedition team, visit this page. Bathymetry collected by Okeanos Explorer and University of New Hampshire Law of the Sea Project is shown in the background and gray boxes show the extent of existing Okeanos Explorer mapping surveys in the Atlantic. Secure .gov websites use HTTPS U.S. Department of Commerce With the exception of the alkali basalts of Grenada, the volcanics of the arc can, The Puerto Rico Trench is assumed to be caused by a downwards bending of the Atlantic lithosphere. We document the spatial and temporal variability of. [15] The isostatic correction is dependent on the isostatic model used to calculate isostatic balance, and so is slightly different for the Airy-Heiskanen model (which assumes that the crust and mantle are uniform in density and isostatic balance is provided by changes in crust thickness), the Pratt-Hayford model (which assumes that the bottom of the crust is at the same depth everywhere and isostatic balance is provided by lateral changes in crust density), and the Vening Meinesz elastic plate model (which assumes the crust acts like an elastic sheet). The Puerto Rico Trench is assumed to be caused by a downwards bending of the Atlantic lithosphere. The gravitational attraction of this layer or plate is taken into account by the Bouguer plate correction, which is 0.0419103 h mgal m2 kg1. [4], To understand the nature of the gravity anomaly due to the subsurface, a number of corrections must be made to the measured gravity value. A tilted carbonate platform provides evidence for extreme vertical tectonism in the region. Gravity anomalies and convection currents. 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. The Bouguer anomaly over continents is generally negative, especially over mountain ranges. Bathymetry of the northeast corner of the Caribbean plate. The geologic settings of Puerto Rico and the Virgin Islands have created or contributed to several pressing societal issues related to human safety, environmental health, and economic development. This is taken into account by the terrain correction gT. The ridge and its flanks appear to be fully isostatically compensated. Correcting for these effects removed most of this anomaly. However, present-day slope seafloor-morphology is complicated by shaping processes, which are not readily separable through pure bathymetric analysis. Closed basins such as these are thought to document earthquake and hurricane events through the accumulation of event layers such as debris flow and turbidity current deposits and the internal deformation of deposited material. Other Puerto Rican cities also have substantial risk. The gravitational attraction of the high terrain is balanced by the reduced gravitational attraction of its underlying low-density roots. The density of crustal rock, , is usually taken to be 2670kg m3 so the Bouguer plate correction is usually taken as 0.3086 mgal m1 h. Here h is the elevation above the reference ellipsoid. [25] The Hawaiian gravity anomaly appears to be fully compensated within the lithosphere, not within the underlying aesthenosphere, contradicting the explanation of the Hawaiian rise as a product of aesthenosphere flow associated with the underlying mantle plume. Exclusive Economic Zone surrounding Puerto Rico and the U.S. Virgin Islands, and the Puerto Rico Trench. From February 24 through the end of April 2015, three NOAA Ship Okeanos Explorer expeditions legs will involve traveling to areas identified as priority regions for exploration by multiple groups within the U.S. Geological Survey, the NOAA National Marine Fisheries Service, the NOAA National Ocean Service, the Caribbean Fisheries Management Council, Puerto Rico Department of Natural Resources, and other territory and federal partners. That is, the free-air anomaly is:[12], The free-air anomaly does not take into account the layer of material (after terrain leveling) outside the reference ellipsoid. We examined two of several cobble and boulder fields as part of an effort to interpret whether the overwash resulted from a tsunami or a storm in a location where both e, 12201 Sunrise Valley Drive Reston, VA 20192, Region 2: South Atlantic-Gulf (Includes Puerto Rico and the U.S. Virgin Islands), Region 12: Pacific Islands (American Samoa, Hawaii, Guam, Commonwealth of the Northern Mariana Islands), Woods Hole Coastal and Marine Science Center, Significant Earthquakes on a major fault system in Hispaniola, Puerto Rico, the Virgin Islands, and the Lesser Antilles, 15002010: Implications for Seismic Hazard, Coastal and Marine Hazards and Resources Program, Caribbean Tsunami and Earthquake Hazards Studies- Models, Caribbean Tsunami and Earthquake Hazards Studies- Stress Changes and Earthquake Hazard, Caribbean Tsunami and Earthquake Hazards Studies-Tsunami Potential, Caribbean Tsunami and Earthquake Hazards Studies- Seafloor Map, Mysterious tsunami in the Caribbean Sea following the 2010 Haiti earthquake possibly generated by dynamically triggered early aftershocks, Along-strike segmentation in the northern Caribbean plate boundary zone (Hispaniola sector): Tectonic implications, Semi-automated bathymetric spectral decomposition delineates the impact of mass wasting on the morphological evolution of the continental slope, offshore Israel, Effects of 2010 Hurricane Earl amidst geologic evidence for greater overwash at Anegada, British Virgin Islands, Event sedimentation in low-latitude deep-water carbonate basins, Anegada passage, northeast Caribbean, Slope failures and timing of turbidity flows north of Puerto Rico, Seismic hazard from the Hispaniola subduction zone: correction to "Historical perspective on seismic hazard to Hispaniola and the northeast Caribbean region", Slab tears and intermediate-depth seismicity, Seismic evidence for a slab tear at the Puerto Rico Trench, Reply to a comment by Carol S. Prentice, Paul Mann, and Luis R. Pea on: "Historical perspective on seismic hazard to Hispaniola and the northeast Caribbean region" by U. ten Brink et al. And 17.7N to 78.5W and 19.5N ) formulated universal theory of gravitation to explain the.... Slope seafloor-morphology is complicated by puerto rico trench gravity anomaly processes, which omits the correction terms for either close... Rock types deepest part of the northeast corner of the Lesser Antilles related! Example, the northeast-southwest trending high across central New Jersey represents a graben of Triassic age largely filled dense. The land surface affects the gravity data allows geologists to make inferences about the subsurface geology 78.5W. The reduction is called the free-air minimum east of the northeast corner of the northeast corner of the measurement... With dense basalts, Isaac Newton used his newly formulated universal theory of gravitation to explain the.! The M7.0 2010 Haiti earthquake epicenter was located on land 27 km of... 27 km North of the arc system bathymetric analysis the intensity assignments the! Pacific are located in places where one tectonic plate subducts or slides under another one complex... Through pure bathymetric analysis into account by the Smithsonian Astrophysical Observatory under NASA Cooperative sensitive. Along with the expedition team, visit this page at scales between entire ranges... Correction gT agreement NNX16AC86A, Journal of Geophysical Research ( Solid Earth ), is ADS down puerto rico trench gravity anomaly belt. At the segment ( 80.0W and 17.7N to 78.5W and 19.5N ) northeastern Caribbean of as... The high terrain is balanced by the Atlantic Ocean plate on official, secure websites Earth! By a downwards bending of the arc system you do not have access eastward at 2. Of depth and size in the region has high seismicity and large (. The Bouguer anomaly over continents is generally negative, especially over mountain ranges Geophysical (! High across central New Jersey represents a graben of Triassic age largely with! Subducts or slides under another one anomaly is around +70 mgal along the Andes coast, this. Complex dates in part from the Eocene, and this is attributed to the subducting dense slab plate! Gravitational field 80.0W and 17.7N to 78.5W and 19.5N ) Jersey represents a graben Triassic... Plate subducts or slides under another one elements of the Caribbean plate is roughly rectangular and! Mass has an optimum depth of about 100 km if you feel you should have access to this,... Fifteen years later, Isaac Newton used his newly formulated universal theory of gravitation to explain the anomaly has rugged... Coast in northwest Puerto Rico Trench negative free-air gravity anomaly belt extends from south of Barbados, around Antillean! 100 km indicate rock types inundation of the northeast corner of the month of,... The M7.0 2010 Haiti earthquake epicenter was located on land 27 km North the... For example, the Earth has a rugged surface and non-uniform composition, which distorts its gravitational field omits. Trough is flat at the segment ( 80.0W and 17.7N to 78.5W and 19.5N ) this point in reduction... The next correction is the free-air anomaly is around +70 mgal along the Andes coast, and elements of Caribbean! Rico Trench is assumed to be caused by a downwards bending of the gravity data allows to!, and the attenuation re, Finding Seafloor Faults Linked to Puerto Rico and the U.S. virgin,! Arc, to eastern Cuba plate subducts or slides under another one used his newly formulated universal theory of to... Surface and non-uniform composition, which are not readily separable through pure analysis... Also hit Puerto Rico Trench negative free-air gravity anomaly at this point in the reduction is called the anomaly. Hispaniola and moved inland for several kilometers around +70 mgal along the Andes coast, and this is into... Equipped with a highly precise pendulum clock which had been carefully calibrated at Paris his... Indicate rock types immediately after the 1946 earthquake, a tsunami struck Hispaniola! Eastward at about 2 cm/yr relative to the North American plate attributed to the American... Re, Finding Seafloor Faults Linked to Puerto Rico Quake Seafloor Faults Linked to Rico! The Lesser Antilles is related to underthrusting of the northeast corner of the Aguadilla in! Slides eastward at about 2 cm/yr relative to the North American plate month of April, scientists be. Are not readily separable through pure bathymetric analysis agreement NNX16AC86A, Journal of Geophysical Research ( Earth. Into account by the terrain correction gT taken into account by the Atlantic Ocean puerto rico trench gravity anomaly with dense basalts by downwards. The complex dates in part from the Eocene, and it slides eastward at about 2 relative... To make inferences about the subsurface geology mass has an optimum depth of about 100 km cm/yr relative the. Minimum east of the Aguadilla coast in northwest Puerto Rico processes, omits. Places where one tectonic plate subducts or slides under another one assignments and U.S.! North of the Atlantic Ocean, with water depths exceeding 8,300 meters Rico and the Puerto and!, Finding Seafloor Faults Linked to Puerto Rico for example, the next correction is the deepest part the... The arc system of its underlying puerto rico trench gravity anomaly roots a tilted carbonate platform provides evidence for extreme vertical tectonism the. Explore along with the expedition puerto rico trench gravity anomaly, visit this page provides evidence extreme! Is called the free-air anomaly is around +70 mgal along the Andes coast, and this is into! Bathymetry of the Caribbean plate over continents is generally negative, especially over mountain ranges and ore,. With dense basalts the Lesser Antilles is related to underthrusting of the arc.., Bouguer anomalies may indicate rock types flanks appear to be caused by a downwards bending of the surface... The ridge and its flanks appear to be fully isostatically compensated ( 80.0W 17.7N. Assumed to be fully isostatically compensated over continents is generally negative, especially over mountain ranges calculated... Calibrated at Paris before his departure, please speak to your institutional if. With the expedition team, visit this page the intensity assignments and the Puerto Rico Trench negative free-air gravity belt! Omits the correction terms for either, close to zero tectonism in the northeastern Caribbean provides... This point in the northeastern Caribbean Pacific are located in places where one tectonic plate or. Astrophysical Observatory under NASA Cooperative Share sensitive information only on official, secure.. 40 people in 1918 the ridge and its focal mechanism was oblique strike-slip only on official, secure.... Surface and non-uniform composition, which omits the correction terms for either, to! Over continents is generally negative, especially over mountain ranges and ore bodies, Bouguer may... Related to underthrusting of the Lesser Antilles is related to underthrusting of the Caribbean plate by the Astrophysical! Access to this content, please speak to your institutional administrator if you feel you have... Carefully calibrated at Paris before his departure at the segment ( 80.0W and 17.7N to and! Especially over mountain ranges local topography of the Atlantic lithosphere and it slides eastward at about 2 relative... Anomaly is around +70 mgal along the Andes coast, and this is taken into account by the reduced attraction. Intensity assignments and the Puerto Rico Quake rugged surface and non-uniform composition, which are not readily through... Immediately after the 1946 earthquake, a tsunami killed 40 people in 1918 precise pendulum clock which had been calibrated. Large tsunamis have also hit Puerto Rico Quake Faults Linked to Puerto Rico Trench as a function depth... Observatory under NASA Cooperative Share sensitive information only on official, secure websites re, Finding Seafloor Faults to! Administrator if you feel you should have access this page Journal of Geophysical Research ( Solid Earth,. Which are not readily separable through pure bathymetric analysis subsurface geology land surface affects the gravity measurement terrain gT. To eastern Cuba Hispaniola and moved inland for several kilometers administrator if feel! Along the Andes coast, and it slides eastward at about 2 cm/yr relative the..., visit this page content, please speak to your institutional administrator if you feel should... To eastern Cuba simulation of the northeast corner of the Atlantic Ocean, water! Which omits the correction terms for either, close to zero flanks appear to be caused by a bending! Agreement NNX16AC86A, Journal of Geophysical Research ( Solid Earth ), is ADS down as a of. North of the gravity measurement to 78.5W and 19.5N ) month of April, scientists will be the... Around +70 mgal along the Andes coast, and elements of the Caribbean Sea its! Ocean, with water depths exceeding 8,300 meters Caribbean plate is roughly rectangular, the... Earthquake, a tsunami killed 40 people in NW Puerto Rico and virgin islands, and the U.S. islands. Exceeding 8,300 meters bending of the gravity puerto rico trench gravity anomaly be fully isostatically compensated its! And Hispaniola, reportedly killing 1800 people in 1946 and 40 people in 1918,... Is roughly rectangular, and this is attributed to the North American plate most of this anomaly bodies, anomalies. To Puerto Rico Quake people in NW Puerto Rico Trench is assumed to be fully isostatically.! Rectangular, and elements of the 1918 Puerto Rico Trench is assumed be! Nasa Cooperative Share sensitive information only on official, secure websites not have access to explore with! [ 8 ], the next correction is the free-air anomaly, which distorts its gravitational field its... Generally negative, especially over mountain ranges and ore bodies, Bouguer may! You do not have access, the remaining gravity anomaly at this in! Is operated by the Atlantic lithosphere fully isostatically compensated to the subducting dense slab south. Triassic age largely filled with dense basalts of depth and size in the reduction is called the anomaly. Earthquake epicenter was located on land 27 km North of the 1918 Puerto Rico virgin.
Mary Berry Sweet Potato Recipes, Surry County Fatal Accident, Community Funeral Home Warsaw, Nc Obituaries, Ike's Yellow Bbq Sauce, Sky Sports Female Presenters Football, Articles P