The Motagua Fault (also, Motagua Fault Zone) is a major, active left lateral-moving

transform fault A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either an ...

which cuts across

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

. It forms part of the

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

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 The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

. Its western end appears not to continue further than its surface trace, where it 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

graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

s across the region that show evidence of counter-clockwise rotation over time.

Guatemala City Guatemala City (, also known colloquially by the nickname Guate), is the Capital city, national capital and largest city of the Guatemala, Republic of Guatemala. It is also the Municipalities of Guatemala, municipal capital of the Guatemala Depa ...

lies in one of these grabens, which may contribute to the seismic hazard posed to 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 the zone reveal that the motion of the North American / Caribbean plate Boundary is, for the most part, accommodated by the Motagua Fault.

Earthquakes

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 A fault trace describes the intersection of a Fault (geology), 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 outwar ...

.USGS Historic Earthquakes
/ref> 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. Information about historical earthquakes is determined by digging trenches along the fault zone and consulting historical records and documents.

Notes

References

External links

Datapages, Volume 28 (1978)USGS Map
{{Faults Seismic faults of Guatemala Seismic faults of Mexico Strike-slip faults Motagua Geographic areas of seismological interest Pacific Coast of Mexico