The Chixoy-Polochic Fault , also known as Cuilco-Chixoy-Polochic Fault , is a major fault zone in Guatemala and southeast Mexico . It runs in a light arc from the east coast of Guatemala to Chiapas , following the deep valleys of the Polochic River , Chixoy River and Cuilco River .
21-711: The Chixoy-Polochic Fault is a large, dominantly strike-slip, left-lateral fault that runs largely parallel to the Motagua Fault situated some 45 km to its south. Both fault zones are onshore extensions of the Bartlett Deep, or Cayman Trench of the Caribbean Sea , which marks the tectonic boundary between the Caribbean plate and the North American plate . Both faults connect at sea west of
42-400: A 2008 study was able to identify a series of faults on the surface of Mars based on how their traces are expressed. These traces appear as erosion resistant ridges thought to have been formed by water deposited minerals within ancient fault zones. Finding these fault traces means that there may have been plate tectonics , geothermal interactions, and movement of ground water at some point in
63-458: A complete fault. Mars has always been an interesting topic across scientific disciplines. The possibility of life existing on another planet has intrigued many throughout history and identifying features like faults could mean that there are more forces at work than previously thought. Using images captured by the Viking , Mars Express , Mars Reconnaissance Orbiter and Mars Odyssey missions,
84-429: A fault moves, the material both at and beneath the surface gets disturbed. These disturbances often cause different rocks and sediment, which are composed of different minerals , as well as fluids to be brought to the surface. Different minerals can contain different nutrients and elements that either enrich soils around them, or alter them in such a way that makes it more difficult for plants to grow. These changes in
105-506: A fault, known as fault blocks , separate horizontally or vertically. Faults , at the broadest level, can be differentiated by the relative motion between their fault blocks . Horizontal motion is indicative of what is known as a strike-slip fault and does not usually show much vertical separation. This is when the motion along the fault is parallel to the fault trace, usually caused by underlying plate tectonics . These fault traces are often identified by some kind of linear feature on
126-400: A fault. A portion of the land can be dropped down or thrust up during faulting and these can be obvious fault trace indicators, especially if seen in linear formations. Riedel shear structures are common structures that can be identified within shear zones. These structures form during the early stages of fault development and eventually link up with each other in linear orientation to form
147-478: A new face which had previously been buried and extends along the length of the fault trace. This new face is a specific type of fault trace known as a fault scarp . As mentioned above, a scarp is a formation caused by vertical offset between two fault blocks . Fault scarps can be seen as meter high faces abruptly jutting out of the surface, or a small face only a few centimeters high which will be smoothed out quickly by mass wasting and erosional forces. As
168-497: Is a major, active left lateral-moving transform fault which cuts across Guatemala . It forms part of the tectonic boundary between the North American plate and the Caribbean plate . It is considered the onshore continuation of the Swan Islands Transform Fault and Cayman trench , which run under the Caribbean Sea . Its western end appears not to continue further than its surface trace, where it
189-467: Is covered by Cenozoic volcanics. The measured length of the fault is approximately 350 km and is the longest fault in Guatemala. Motion of the fault and others in the plate boundary have formed north–south trending grabens across the region that show evidence of counter-clockwise rotation over time. Guatemala City lies in one of these grabens, which may contribute to the seismic hazard posed to
210-458: The fault blocks are pulled away from each other or pushed towards each other. This is known as a dip-slip fault . This causes vertical separation between the blocks as one is dropped down in the space created by extensional forces, or one block is shoved up on top of the other by compressional forces. Again, the underlying regional plate tectonics are often responsible for the type of fault and associated trace. This vertical separation reveals
231-658: The Guatemalan coast. To the west, the Polochic fault may branch onto the Tonala fault of western Chiapas. It does not continue at sea across the Pacific coastal plain and marine shelf. The Chixoy-Polochic fault has total displacement of 125 km, well constrained by the offset of Paleocene or Eocene laramide folds and thrusts. Fault velocity has been estimated at 4.8 ± 2.3 mm/y over the past 10 ky, 2.5–3.3 mm/y over
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#1732765363103252-615: The city's inhabitants. The Motagua Fault is regarded by some geologists as part of a system of faults designated the "Motagua-Polochic system" rather than as a discrete single boundary. The Polochic fault (also referred to as the Chixoy-Polochic Fault) lies north and parallel to the Motagua Fault and shares some of the motion between the North American and Caribbean plates. Studies of GPS displacement of
273-536: The earth at different scales. Large scale images often unveil features that were difficult or impossible to see from previous available perspectives. Sudden 90 degree bends or jogs in a stream, or even an extended straight stretch could be possible indicators of a fault trace but when put into larger perspective can be aligned with other pieces of evidence to add confirmation. There could be a gentle elevation change that don't seem suspicious when walking over it, but when viewed remotely can show that it extends laterally in
294-427: The fault's length. The quake damaged a large amount of the country's infrastructure and resulted in the deaths of 23,000 people. Information about historical earthquakes is determined by digging trenches along the fault zone and consulting historical records and documents. 15°08′N 89°22′W / 15.133°N 89.367°W / 15.133; -89.367 Fault trace A fault trace describes
315-540: The intersection of a geological fault with the Earth's surface, which leaves a visible disturbance on the surface, usually looking like a crack in the surface with jagged rock structures protruding outward. The term also applies to a line plotted on a geological map to represent a fault. These fractures tend to occur when a slip surface expands from a fault core, especially during an earthquake . This tends to occur with fault displacement, in which surfaces on both sides of
336-745: The last 7–10 Myr , and less than 5 mm/y during the current interseismic cycle. While recent seismic activity is more prominent in the Motagua fault, some studies suggest the Chixoy-Polochic Fault is still capable of producing major earthquakes. The magnitude 7.5–7.8 M w 1816 Guatemala earthquake of western Guatemala has been ascribed to the Polochic Fault, although this has been disputed. Most recent recorded fault activity includes at least for slip events between 17 ka and 13 ka BP , and aseismic surface rupture over some of
357-656: The past 5 centuries. One or several intermediate to large earthquakes between 850 CE and 1,400 CE , including a cluster of 4 earthquakes over 60 years during the Classic Maya collapse . The fault display a 5 km to 10 km deep zone of microseismicity which may represent a locked zone. Only ≤ 5.6 M w earthquakes have occurred on the fault since the beginning of regional instrumental records (1920 CE). 15°28′N 89°22′W / 15.467°N 89.367°W / 15.467; -89.367 Motagua Fault The Motagua Fault (also, Motagua Fault Zone )
378-502: The planets history. These factors all have major potential to influence the chances of living organisms existing there. Because of the rarity of linear features found in nature, technologies which allow for large scale map view analysis of the earth's surface have been increasingly helpful in revealing fault traces that have otherwise remained unrecognized. Remote Sensing techniques use imagery acquired by sensors mounted on satellites, aircraft, or even handheld to view different parts of
399-560: The soil can cause noticeable changes in the vegetation and form a fault trace. Not only are large scale linear features indicative of fault traces but small lineations found on rock samples or rock faces also are. Slickenlines are one type of lineation which are linear gouges scraped into a rock from different rocks grinding along against each other. Slickenlines indicate a fault as well as its motion, which can be very useful in many studies. Similar to fault scarps, and often displayed as them, elevation changes can often be good indicators of
420-413: The surface such as a fence line or small stream that has been offset. There are many photos of straight fences that suddenly jump over a meter or two leaving a gap in between. In nature, linear features are uncommon and can help identify geologic features like faults because of their linear fault traces. Dip separation can also occur when motion of the fault is perpendicular to the fault trace. That is,
441-435: The zone reveal that the motion of the North American / Caribbean plate Boundary is, for the most part, accommodated by the Motagua Fault. The Motagua Fault has been responsible for several major earthquakes in Guatemala 's history, including the 7.5 M w Guatemala 1976 earthquake , and is also notable for its significant visible fault trace . The event caused 2 meters of vertical displacement and ruptured 230 km of
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