Motagua Fault | |
---|---|
Motagua Fault Zone | |
Location | Guatemala and Mexico |
Tectonics | |
Plate | North American Plate, Caribbean Plate |
Status | Active |
Earthquakes | 1717, 1773, 1902, 1976, 1980, 2009 |
Type | transform fault |
The Motagua Fault (also, Motagua Fault Zone) 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. [1] Its western end appears not to continue further than its surface trace, [2] where it is covered by Cenozoic volcanics. [1]
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 the city's inhabitants. [3]
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. [1] Studies of GPS displacement of the zone reveal that the motion of the North American / Caribbean Plate Boundary is, for the most part, accommodated by the Motagua Fault. [3]
The Motagua Fault has been responsible for several major earthquakes in Guatemala's history, including the 7.5 Mw Guatemala 1976 earthquake, and is also notable for its significant visible fault trace. [4] The event caused 2 meters of vertical displacement and ruptured 230 km of the fault's length. The quake damaged a large amount of the country's infrastructure and resulted in the deaths of 23,000 people. [3]
Information about historical earthquakes is determined by digging trenches along the fault zone and consulting historical records and documents. [3]
The San Andreas Fault is a continental right-lateral strike-slip transform fault that extends roughly 1,200 kilometers (750 mi) through the U.S. state of California. It forms part of the tectonic boundary between the Pacific Plate and the North American Plate. Traditionally, for scientific purposes, the fault has been classified into three main segments, each with different characteristics and a different degree of earthquake risk. The average slip rate along the entire fault ranges from 20 to 35 mm per year.
The Cayman Trough is a complex transform fault zone pull-apart basin which contains a small spreading ridge, the Mid-Cayman Rise, on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate. It extends from the Windward Passage, going south of the Sierra Maestra of Cuba toward Guatemala. The transform fault continues onshore as the Polochic-Motagua fault system, which consists of the Polochic and Motagua faults. This system continues on until the Chiapas massif where it is part of the diffuse triple junction of the North American, Caribbean and Cocos plates.
The North American Plate is a tectonic plate containing most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of 76 million km2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific Plate.
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the northern coast of South America.
The Motagua River is a 486-kilometre-long (302 mi) river in Guatemala. It rises in the Western Highlands of Guatemala and runs in an easterly direction to the Gulf of Honduras. The Motagua River basin covers an area of 12,670 square kilometres (4,890 sq mi) and is the largest in Guatemala.
The outer trench swell, outer trench high, or outer rise is a subtle ridge on the seafloor near an oceanic trench, where a descending plate begins to flex and fault in preparation for its descent into the mantle at a subduction zone. The lithosphere is bent upwards by plate stresses, and is not in isostatic equilibrium.
The Middle America Trench is a major subduction zone, an oceanic trench in the eastern Pacific Ocean off the southwestern coast of Middle America, stretching from central Mexico to Costa Rica. The trench is 1,700 miles (2,750 km) long and is 21,880 feet at its deepest point. The trench is the boundary between the Rivera, Cocos, and Nazca plates on one side and the North American and Caribbean plates on the other. It is the 18th-deepest trench in the world. Many large earthquakes have occurred in the area of the Middle America Trench.
The 1976 Guatemala earthquake struck on February 4 at 03:01:43 local time with a moment magnitude of 7.5. The shock was centered on the Motagua Fault, about 160 km northeast of Guatemala City at a depth of 5 kilometers (3.1 mi) near the town of Los Amates in the department of Izabal.
The 2009 Swan Islands earthquake occurred on May 28 at 02:24:45 AM local time with a moment magnitude of 7.3 and a maximum Mercalli intensity of VII. The epicenter was located in the Caribbean Sea, 64 kilometres (40 mi) northeast of the island of Roatán, 19 miles northeast of Port Royal, Isla de Bahias, 15 miles northwest of Isla Barbaretta, and 130 kilometres (81 mi) north-northeast of La Ceiba. Three aftershocks followed the earthquake within magnitude 4 range.
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.
The Gonâve Microplate forms part of the boundary between the North American Plate and the Caribbean Plate. It is bounded to the west by the Mid-Cayman Rise spreading center, to the north by the Septentrional-Oriente fault zone and to the south by the Walton fault zone and the Enriquillo–Plantain Garden fault zone. The existence of this microplate was first proposed in 1991. This has been confirmed by GPS measurements, which show that the overall displacement between the two main plates is split almost equally between the transform fault zones that bound the Gonâve microplate. The microplate is expected to eventually become accreted to the North American Plate.
The 1842 Cap-Haïtien earthquake occurred at 17:00 local time on 7 May. It had an estimated magnitude of 8.1 on the Ms scale and triggered a destructive tsunami. It badly affected the northern coast of Haiti and part of what is now the Dominican Republic. Port-de-Paix suffered the greatest damage from both earthquake and tsunami. Approximately 5,000 people were killed by the effects of the earthquake shaking and another 300 by the tsunami.
On 9 January 2018, at approximately 8:51 p.m. local time, a magnitude 7.5 earthquake struck in the Yucatán Basin of the Caribbean Sea, 44 kilometres (27 mi) east of Great Swan Island off the coast of Honduras. The earthquake was felt across Central America, and rattled windows in Tegucigalpa. The earthquake was also felt in the Cayman Islands.
The Chortis Block is a 400–600 km (250–370 mi)-wide continental fragment in Central America located in the northwest corner of the oceanic Caribbean Plate.
The geology of Guatemala encompasses rocks divided into two tectonic blocks. The Maya Block in the north has igneous and metamorphic North American Craton basement rocks, overlain by late Paleozoic metasedimentary rocks, which experienced deformation during the Devonian. Red beds, evaporites and marine limestone from the Mesozoic overlie these rocks. A karst landscape formed in the thick limestone units across the north of the country. During a collisional orogeny, these Paleozoic and Mesozoic rocks were uplifted, thrust and folded as the Central Guatemalan Cordillera. Paleogene rocks from the early Cenozoic include volcanic and marine clastic rocks, associated with high rates of erosion.
The 2022 Guatemala earthquake occurred on the early morning of February 16, 2022 in the southern regions of Guatemala. The quake measured a moment magnitude of 6.2 and reached a peak intensity of VI (Strong) on the Modified Mercalli Intensity scale. Damage was widespread but light in and around the capital, Guatemala City, resulting mostly in cracked walls and rockslides.
The Maya Block, also known as the Maya Terrane, Yucatan Block, or Yucatan–Chiapas Block, is a physiographic or geomorphic region and tectonic or crustal block in the southernmost portion of the North American Plate.