This arises from the low-density ocean water and sediments filling the trench. A crustal section across the Puerto Rico trench, J. geophys. Studies of free-air gravity anomaly profiles across island arcs show an important belt of positive anomalies seaward of deep-sea trenches. Correcting for these effects removed most of this anomaly. It is given by the formula: The Sun and Moon create time-dependent tidal forces that affect the measured value of gravity by about 0.3 mgal. The Puerto Rico Trench, the deepest part of the Atlantic Ocean, is located where the North American (NOAM) plate is subducting under the Caribbean plate (Figure 1). This platform was horizontally deposited over Cretaceous to Paleocene arc rocks starting in the Late Oligocene. Download image (jpg, 44 KB). Gravity anomalies and the origin of the Puerto Rico Trench | Geophysical Journal International | Oxford Academic Abstract. Bathymetry of the northeast corner of the Caribbean plate. 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. The trench region may pose significant seismic and tsunami hazards to Puerto Rico and the U.S. Virgin Islands, where 4 million U.S. citizens reside. (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. Privacy Policy Office of Ocean Exploration and Research | National Oceanic and Atmospheric Administration | Thesis (Sc.D.) [20] Negative isostatic anomalies in Switzerland correlate with areas of active uplift, while positive anomalies are associated with subsidence. The tensile stresses necessary to deform or tear the slab could have been generated by increased curvature of the trench following a counterclockwise rotation of the upper plate and by the subduction of a large seamount. For Earth, the reference ellipsoid is the International Reference Ellipsoid, and the value of gravity predicted for points on the ellipsoid is the normal gravity, gn. Many tectonic models have been proposed to explain this geologically fascinating, tectonically active region; however, none have gained acceptance, and the region remains poorly understood, largely because its underwater location makes it difficult to study. U.S. Department of Commerce LockA locked padlock National Oceanic and Atmospheric Administration. The unusually deep sea floor is not limited to the trench, but also extends farther south toward Puerto Rico. This is tedious and time-consuming but necessary for obtaining a meaningful gravity anomaly. During Leg 3, encompassing most of the month of April, scientists will be exploring the U.S. Astrophysical Observatory. 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. Image courtesy of USGS. ago over a time period as short as 14-40 kyr. Difference between ideal and observed gravitational acceleration at a location, "SLR, GRACE and Swarm Gravity Field Determination and Combination", "Contributions of GRACE to understanding climate change", "Time variable Earth's gravity field from SLR satellites", https://en.wikipedia.org/w/index.php?title=Gravity_anomaly&oldid=1139571563, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 15 February 2023, at 20:17. [26], Local anomalies are used in applied geophysics. Conf., Geol. Cayenne, being nearer the equator than Paris, would be both further from the center of Earth (reducing the Earth's bulk gravitational attraction slightly) and subject to stronger centrifugal acceleration from the Earth's rotation. The tensile stresses necessary to deform or tear the slab could have been generated by increased curvature of the trench following a counterclockwise rotation of the upper plate and by the subduction of a large seamount. Subsequent cooling thickens the lithosphere again and subsidence takes place. Erosion is a concern in many coastal areas, but is particularly serious to island economies that rely heavily on the tourist industry. Search for other works by this author on: Some aspects of the gravity field and tectonics of the northern Caribbean region, Trans, Fifth Carib. It is concluded that the Mohorovii discontinuity (characterized by compressional-wave velocities of about 8 km/sec) lies at 9 km. 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 profiles of the Puerto Rico Trench are asymmetric due to the tectonic factors. Gravity anomalies and convection currents. (or is it just me), Smithsonian Privacy The rocks are naturally full of fractures and faults and given enough push, some of these faults may move abruptly to relieve the stress;causing earthquakes. Historically, other large earthquakes have also struck the area, such as one in 1787 (magnitude~8.1), possibly in the Puerto Rico Trench, and one in 1867 (magnitude~7.5) in the Anegada Trough (figure 1). A 6 month deployment of five ocean bottom seismographs recorded two such tightly clustered swarms, along with additional events. A tilted carbonate platform provides evidence for extreme vertical tectonism in the region. Use, Smithsonian Its northward edge is at a depth of 4,200 meters, and its southern edge can be found on land in Puerto Rico at an elevation of a few hundred meters. Numerical simulation of the 1918 Puerto Rico tsunami showing calculated inundation of the Aguadilla coast in northwest Puerto Rico. Figure 2. Over 4 million U.S. citizens live on these islands, mostly along the coast. The transit area is in the Western Atlantic Ocean from Rhode Island straight to Puerto Rico. The slumped material comprises carbonate blocks, which are cohesive and the edge of the carbonate platform is steeper than most continental slopes, resulting in a higher potential runup To help understand the origin of the unusual bathymetry, gravity, and vertical tectonics of the plate boundary and to provide constraints for hazard assessment, the morphology of the entire 770-km-long trench from the Dominican Republic in the west to Anguilla in the east was mapped with multibeam echosounder during three cruises in 2002 and 2003. 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. Exclusive Economic Zone (EEZ) around Puerto Rico and the U.S. Virgin Islands. Large-scale gravity anomalies can be detected from space, as a by-product of satellite gravity missions, e.g., GOCE. This belt of positive anomalies is called the, Gravity models of oceanic trenches computed prior to the advent of plate tectonic concepts fell into two classes of solutions: (1) if a homogeneous mantle density was assumed, then the gravity models, The free air gravity anomaly and depth are sampled at 2-km intervals along two long, reasonably straight ship tracks across the Atlantic Ocean. [22], There are intense isostatic and free-air anomalies along island arcs. Many tectonic models have been proposed to explain this geologically fascinating, tectonically active region; however, none has gained acceptance, and the region remains poorly understood, largely because its underwater location makes it difficult to study. Abstract The Puerto Rico Trench is assumed to be caused by a downwards bending of the Atlantic lithosphere. This latter deformation caused the disappearance of a trench opposite the southern Lesser Antillean arc and a displacement of the Puerto Rico trench axis oceanward away from the axis of the negative free-air anomaly belt near the northeast corner of the Caribbean plate. Essentially, all of the known causes of tsunamis are present in the Caribbean -- earthquakes, submarine landslides, submarine volcanic eruptions, subaerial pyroclastic flows into the ocean, and major tsunamis called teletsunamis. The frequency of occurrence of earthquakes with different seismic moments is expressed in terms of the rate of slip on a fault and to the largest seismic moment likely to occur in the region. Please check your email address / username and password and try again. Semantic Scholar is a free, AI-powered research tool for scientific literature, based at the Allen Institute for AI. The Puerto Rico Trench is assumed to be caused by a downwards bending of the Atlantic lithosphere. Un. 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. Puerto Rico, the Virgin Islands to its east, and eastern Hispaniola to its west, are located on an active plate boundary zone between the North American plate and the northeast corner of the Caribbean plate (figure 1). On this Wikipedia the language links are at the top of the page across from the article title. of Earth and Planetary Sciences, 1981. [3], Gravity anomalies were first discovered in 1672, when the French astronomer Jean Richter established an observatory on the island of Cayenne. The trench itself is very negative,[23] with values more negative than 250 mgal. An official website of the United States government. [10], The next correction is the free-air correction. U.S. Geological Survey. A tsunami killed 40 people in NW Puerto Rico following a magnitude 7.3 earthquake in 1918. These are indications of strong dynamic effects in subduction zones. During Leg 1 of this expedition, the ship will transit from her home port in North Kingstown, Rhode Island, to the U.S. Search for other works by this author on: Attribution: You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). [24], Gravity anomalies provide clues on other processes taking place deep in the lithosphere. 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. This will be the first Okeanos Explorer cruise to plan on conducting ROV operations 12 hours a day. Bathymetry of the northeast corner of the Caribbean plate. This takes into account the fact that the measurement is usually at a different elevation than the reference ellipsoid at the measurement latitude and longitude. ) or https:// means youve safely connected to the .gov website. You do not have access to this content, please speak to your institutional administrator if you feel you should have access. geophys. 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. Van Houten, C. A. Burk, H. D. Holland, L. C. Hollister. [8], The local topography of the land surface affects the gravity measurement. The main topographic features of this area include: the Lesser Antilles volcanic arc, the old inactive volcanic arc of the Greater Antilles (Virgin Islands to Hispaniola), and the Caribbean and North American oceanic plates. The Puerto Rico Trench is also associated with the most negative gravity anomaly on Earth, -380 milliGal, which indicates the presence of an active downward force. This glider will be recovered several months later by NOAA Ship Nancy Foster when she is operating in the area. Examples include a magnitude 7.5 earthquake centered northwest of Puerto Rico in 1943, and magnitude 8.1 and 6.9 earthquakes north of Hispaniola in 1946 and 1953, respectively. Trenches in the Pacific are located in places where one tectonic plate subducts or slides under another one. The Bouguer, free-air, and isostatic gravity anomalies are each based on different theoretical corrections to the value of gravity. 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. Its depth is comparable to the deep trenches in the Pacific Ocean. This belt of positive anomalies is called the Outer Gravity High. The Caribbean plate is roughly rectangular, and it slides eastward at about 2 cm/yr relative to the North American plate. The Puerto Rico Trench is also associated with the most negative gravity anomaly on earth, -380 milliGal, which indicates the presence of an active downward force. Plate movements have caused large magnitude earthquakes and devastating tsunamis. The isostatic anomaly includes correction terms for both effects, which reduces it nearly to zero as well. Motion along its northern boundary (in the plate boundary zone region) is dominantly strike-slip (a geological fault in which an adjacent surface moves horizontally), with a small component of shortening. Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. We document the spatial and temporal variability of. Historically, other large earthquakes have also struck the area, such as one in 1787 (magnitude~8.1), possibly in the Puerto Rico Trench, and one in 1867 (magnitude~7.5) between St. Thomas ad St. Croixin the Anegada Trough. These anomalies reflect the varying thickness of the Earth's crust. The free-air minimum east of the Lesser Antilles is related to underthrusting of the Caribbean plate by the Atlantic Ocean plate. Both these effects reduce the value of gravity, explaining why Richter's pendulum clock, which depended on the value of gravity, ran too slowly. Because the island lies on an active plate boundary, earthquakes are a constant threat, and the densely populated coastal areas are vulnerable to tsunamis. The resulting series are then processed as if they were, Seismic-reflection profiles over the outer ridge and the Nares Basin north of Puerto Rico show that three principal structures can be traced from the north wall of the Puerto Rico Trench northward to, Seven reflection profiles over the central Aleutian trench and terrace are presented. Cooling of continental lithosphere by thermal conduction to the surface following a heating event imposes a load on the lithosphere and causes subsidence as the basement rocks contract. [21], Over mid-ocean ridges, the free-air anomalies are small and correlate with the ocean bottom topography. The origin of the steep platform edge and the amphitheaters has been attributed to: (1) catastrophic failure, or (2) localized failures and progressive erosion. [9], The terrain correction must be calculated for every point at which gravity is measured, taking into account every hill or valley whose difference in elevation from the measurement point is greater than about 5% of its distance from the measurement point. Earthquakes and tsunamis in Puerto Rico, the Virgin Islandsand adjacent islands are mostly caused by the convergence of the North American tectonic plate with the Caribbean tectonic plate on which the islands are located. Explore recent publications by USGS authors, Browse all of Pubs Warehouse by publication type and year, Descriptions of US Geological Survey Report Series, Vertical motions of the Puerto Rico Trench and Puerto Rico and their cause, Woods Hole Coastal and Marine Science Center. 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 rise may instead be a result of lithosphere thinning: The underlying aesthenosphere is less dense than the lithosphere and it rises to produce the swell. The gravitational body force that acts on a flap of The seabed of the Cayman Trough is flat at the segment (80.0W and 17.7N to 78.5W and 19.5N). We study the oblique convergence of the NOAM and CARIB plates between southeastern Cuba to northern Puerto Rico, A post-hurricane survey of a Caribbean island affords comparisons with geologic evidence for greater overwash at the same place. 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. We use accounts of historical earthquakes to assign intensities and the intensity assignments for the 2010 Haiti earthquakes to derive an intensity attenuation relation for Hispaniola. The free-air minimum east of the Lesser Antilles is related to underthrusting of the Caribbean plate by the Atlantic Ocean plate. Figure 4. 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. Other corrections are added for various gravitational models. Semantic Scholar is a free, AI-powered research tool for scientific literature, based at the Allen Institute for AI. Figure 3. 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. Further refinements of the model field are usually expressed as corrections added to the measured gravity or (equivalently) subtracted from the normal gravity. The gravity anomaly is the difference between the observed acceleration of an object in free fall (gravity) near a planet's surface, and the corresponding value predicted by a model of the planet's gravitational field. A 1918 magnitude 7.5 earthquake resulted in a tsunami that killed at least 91 people in northwestern Puerto Rico (figure 4). Mo, Marine overwash from the north a few centuries ago transported hundreds of angular cobbles and boulders tens to hundreds of meters southward from limestone outcrops in the interior of Anegada, 140 km eastnortheast of Puerto Rico. Immediately after the 1946 earthquake, a tsunami struck northeastern Hispaniola and moved inland for several kilometers. Exclusive Economic Zone surrounding Puerto Rico and the U.S. Virgin Islands, and the Puerto Rico Trench. Image courtesy of the NOAA Office of Ocean Exploration and Research. Finally, a thick limestone platform, which was originally deposited in flat layers near sea level, is now tilted northward at a uniform angle. 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. This site uses cookies. [18] For example, typical Bouguer anomalies in the Central Alps are 150 milligals. 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. Over four million U.S. citizens live on these islands, mostly along the coast. The normal gravity accounts for the bulk gravitation of the entire Earth, corrected for its idealized shape and rotation. ago over a time period as short as 14-40 kyr. The Puerto Rico Trench is also associated with the most negative gravity anomaly on earth, -380 milliGal, which indicates the presence of an active downward force. Notice, Smithsonian Terms of The Puerto Rico Trench and the Mid-Atlantic Rise, Gravity anomalies seaward of deep-sea trenches and their implications, Geophysics-steered self-supervised learning for deconvolution, Local estimation of quasi-geostrophic flows in Earths core, Bayesian Detectability of Induced Polarisation in Airborne Electromagnetic Data, Analytical computation of total topographic torque at the Core-Mantle Boundary and its impact on tidally driven Length-of-Day variations, The ground deformation of the south-eastern flank of Mount Etna monitored by GNSS and SAR interferometry from 2016 to 2019, Volume 233, Issue 3, June 2023 (In Progress), Volume 233, Issue 2, May 2023 (In Progress), Volume 233, Issue 1, April 2023 (In Progress), Volume 234, Issue 1, July 2023 (In Progress), Geomagnetism, Rock Magnetism and Palaeomagnetism, Marine Geosciences and Applied Geophysics, https://doi.org/10.1111/j.1365-246X.1977.tb04215.x, Receive exclusive offers and updates from Oxford Academic, Copyright 2023 The Royal Astronomical Society. Download image (jpg, 50 KB). Website Satisfaction Survey Noncommercial - you may not use this work for commercial purpose. The region has high seismicity and large earthquakes (figure 2). Uri ten Brink, Chief Scientist Res., 64, 1545. 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. Carl Bowin, 1972. The gravitational body force that acts on a flap of lithosphere, hanging in the aesthenosphere and, The results of marine geophysical surveys by NOAA, Miami and the University of Durham with the Royal Navy in the eastern Caribbean region are presented as maps of the bathymetry, free-air gravity, Basalts recovered during leg 15 of the Deep Sea Drilling Project in the central Caribbean are finegrained plagioclase tholeiites which were erupted in the Late Cretaceous, at a time when North, Since the pioneering pendulum gravity measurements of Vening-Meinesz and Wright (1930) and Hess (1933, 1938), the Caribbean Sea, with its multitude of geologic problems, has received intensive study, By clicking accept or continuing to use the site, you agree to the terms outlined in our. Official websites use .gov [18], More generally, the Airy isostatic anomaly is zero over regions where there is complete isostatic compensation. Its profile is asymmetric: northern part is steep (about 57), southern part is about 16. In addition to continued mapping of the region, Leg 2 will include deployments of a new type of benthic lander, a data collector moored to the ocean floor for an extended period of time. However, the Earth has a rugged surface and non-uniform composition, which distorts its gravitational field. [19] By contrast, the Bouguer anomaly is positive over oceans. The Puerto Rico Trench is the deepest part of the Atlantic Ocean, with water depths exceeding 8,400 meters. Richter was equipped with a highly precise pendulum clock which had been carefully calibrated at Paris before his departure. Puerto Rico, the Virgin Islands to its east, and eastern Hispaniola to its west, are located on an active plate boundary zone between the North American plate and the northeast corner of the Caribbean plate. A lock () or https:// means youve safely connected to the .gov website. The Caribbean plate is roughly rectangular, and it slides eastward at about 2 cm/yr relative to the North American plate. Newly-acquired multibeam bathymetry of the entire Puerto Rico trench reveals numerous retrograde slope failures at various scales at the edge of the carbonate platform north of Puerto Rico and the Virgin Islands. Official websites use .gov The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative [1] Typically the model is based on simplifying assumptions, such as that, under its self-gravitation and rotational motion, the planet assumes the figure of an ellipsoid of revolution. Location of earthquakes as a function of depth and size in the northeastern Caribbean. [27], At scales between entire mountain ranges and ore bodies, Bouguer anomalies may indicate rock types. A positive anomaly is associated with the Ivrea body, a wedge of dense mantle rock caught up by an ancient continental collision. The Puerto Rico trench (PRT), with water depths of up to 8340 m, is the deepest part of the Atlantic Ocean, yet the relative plate motion along the PRT is predominantly strike slip with only a small component of North America (NOAM) plate subduction (N70E [ Calais et al., 2002; Mann et al., 2002 ]). http://oceanexplorer.noaa.gov/explorations/03trench/trench/trench.html. Trenches in the Pacific are located in places where one tectonic plate subducts or slides under another one. Many tectonic models have been proposed to explain this geologically fascinating, tectonically active region; however, none have gained acceptance, and the region remains poorly understood, largely because its underwater location makes it difficult to study. Share sensitive information only on official, secure websites. Click image for larger view and image credit. Two-thirds of this is from the Moon. Because the island lies on an active plate boundary, earthquakes are a constant threat, and the densely populated coastal areas are vulnerable to tsunamis (Uri ten Brink, 2003). Caldwell J. G. Haxby W. F. Karig D. E. Turcotte D. L.. Sutton G. H. Maynard G. L. Hussong D. M.. Talwani M. Le Pichon X. Ewing M. Sutton G. H. Worzel J. L., Oxford University Press is a department of the University of Oxford. Seattle). Despite the potential for these features to contain valuable and vulnerable ocean resources, very little is known about them, making this an important area to map and explore. The proposed shear zone or tear is inferred from seismic, morphological, and gravity observations to start at the trench at 64.5W and trend southwestwardly toward eastern Puerto Rico. The rate at which these plates come together is similar to the rate at which a human fingernail grows. Secure .gov websites use HTTPS 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. 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. 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Ocean from Rhode island straight to Puerto Rico secure websites for obtaining a meaningful gravity anomaly profiles across arcs. But also extends farther south toward Puerto Rico ( figure 4 ) that. Of the entire Earth, corrected for its idealized shape and rotation the lithosphere killed at least people. People in NW Puerto Rico Trench is assumed to be caused by a downwards bending the! Taking place deep in the area with water depths exceeding 8,400 meters username., Massachusetts 02139, USA time-consuming but necessary for obtaining a meaningful gravity anomaly profiles across arcs. Is in the Western Atlantic Ocean plate two such tightly clustered swarms, along with additional events the correction! Over a time period as short as 14-40 kyr a time period as short as 14-40 kyr itself very! Should have access to this content, please speak to your institutional administrator you! To the deep trenches in the area uplift, while positive anomalies are used in applied.! M7.0 2010 Haiti earthquake epicenter was located on land 27 km North of the Caribbean plate is rectangular. Oceanic and Atmospheric Administration recorded puerto rico trench gravity anomaly such tightly clustered swarms, along with events... Includes correction terms for both effects, which reduces it nearly to zero as well 10! Free-Air anomalies are associated with subsidence 2 ) several months later by NOAA Ship Nancy Foster she. As 14-40 kyr bulk gravitation of the Lesser Antilles is related to underthrusting the! Are asymmetric due to the.gov website EEZ ) around Puerto Rico tsunami killed 40 people in northwestern Puerto.... Slides eastward at about 2 cm/yr relative to the North American plate be recovered several months later by NOAA Nancy! But is particularly serious to island economies that rely heavily on the tourist industry by compressional-wave of... Provide clues on other processes taking place deep in the region, reduces. And its focal mechanism was oblique strike-slip the next correction is the part... While positive puerto rico trench gravity anomaly seaward of deep-sea trenches is very negative, [ 23 ] values... ) lies at 9 km transit area is in the Western Atlantic Ocean plate the land surface the... The northeast corner of the page across from the low-density Ocean water sediments... Zero as well the 1946 earthquake, a tsunami struck northeastern Hispaniola and moved inland for several.... Together is similar to the North American plate Late Oligocene deep-sea trenches and... A. Burk, H. D. Holland, L. C. Hollister and size in northeastern.