1972 Nicaragua earthquake
| Date | December 23, 1972 |
|---|---|
| Origin time | 6:29 UTC |
| Magnitude | 6.2 Mw |
| Depth | 5 kilometres (3 mi) |
| Epicenter | 12°18′N 86°06′W / 12.3°N 86.1°WCoordinates: 12°18′N 86°06′W / 12.3°N 86.1°W |
| Areas affected | Nicaragua |
| Casualties | 6,000 |
The 1972 Nicaragua earthquake occurred at 12:29 a.m. local time (06:29 UTC) on Saturday, December 23 near Managua, the capital of Nicaragua. It had a magnitude of 6.2, with the epicenter 28 kilometers northeast of the city centre, and a depth of about 5 kilometers. Within an hour after the main shock, two aftershocks, one of magnitude 5.0 and the other 5.2, occurred at 1:18 a.m. and 1:20 a.m. The earthquake caused widespread casualties among Managua's residents: 6,000 were killed, 20,000 were injured and over 250,000 were left homeless.
Managua, which lies on the southern shore of Lake Xolotlan, near the western coast of Nicaragua, is situated within an active volcanic zone known as the Central American Volcanic Chain. The city has a long history of volcanic and seismic activity which arise from the relative movements of two crustal plates which intersect near the southwestern border of Central America. The Cocos plate, located east of the East Pacific Rise, is moving northeastward and is slowly being submerged under the Caribbean Plate. The zone of dipping is initiated at the surface of the Middle America Trench, which extends 4 to 5 kilometers deep along the Pacific Coast from Mexico to Costa Rica. But rather than a simple crustal movement between the two plates the earthquake was believed to have been caused by a shallow adjustment to geological pressure at the south western corner of the Caribbean plate.
One of the most significant geological effects of the 1972 Nicaragua earthquake quake was surface faulting. Examination of the fault lines indicated a lateral motion moving in a northeasterly direction and aftershock data has revealed at least one of the faults extends from the surface to a depth of 8 to 10 kilometers beneath the city of Managua.
The earthquake severely damaged an area of 27 square kilometers and destroyed 13 square kilometers in the city centre. The majority of the buildings in the central business district sustained significant structural damage including a 19-story building, one 15-story building, approximately 5 buildings in the 7 to 9 story range and well over 25 buildings in the 3 to 6 story range. Much of the damage arose from seismic ground movement which occurred within 10–15 seconds of the main shock. The majority of the factories and smaller buildings were severely damaged. Many of the houses and small shops were over 40 years old and constructed of taquezal or talquezal, which have walls that are timber frames filled with stone and finished with plaster, and roofs of unmortared clay tiles. This architecture is far from earthquake resistant, something that became fatally evident. An estimated 53,000 homes in the city were affected.
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