1992 Murindó earthquake
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  | |
| UTC time | 1992-10-18 15:11:59 |
|---|---|
| ISC event | 268025 |
| 268313 | |
| USGS-ANSS | ComCat |
| ComCat | |
| Local time | 03:32 |
| 10:11 | |
| Magnitude | 7.2 Mwb |
| Depth | 10.0 km |
| Epicenter | 7°04′30″N 76°51′43″W / 7.075°N 76.862°W |
| Type | Strike-slip |
| Areas affected | Colombia |
| Max. intensity | MMI X (Extreme) MSK-64 X (Devastating) XI (ESI 2007)[1] |
| Foreshocks | 6.7 Mw |
| Casualties | 10 dead, 115 injured |
The 1992 Murindó earthquake (also known as the Atrato earthquake) occurred on October 18 at 15:11 UTC (10:11 a.m. local time) with an epicenter in the Department of Chocó, northern Colombia. The shallow magnitude 7.2 earthquake struck northwest of the town of Murindó, killing ten and injured more than a hundred.[2] Thirty-three municipalities were severely damaged.[2]
The preferred focal mechanism of this earthquake is highly debated with either thrust, reverse, or left-lateral strike-slip.
Subduction of the Nazca plate beneath the North Andes plate (part of the South American plate) occasionally produces moderately large to great earthquakes along the coast of Colombia. The megathrust fault forms the northern part of the Peru–Chile Trench, which has been the source of very large earthquakes including the 1906 Ecuador–Colombia earthquake; the magnitude 8.8 is the biggest in the region and the 6th largest earthquake to be instrumentally recorded.
Earthquake
From the earthquake's depth and proximity to the trench, this was not a subduction-related earthquake.
On October 17, a magnitude 6.7 foreshock struck between Murindó and Opogodó 31 hours before the mainshock. Its focal mechanism was of reverse origin.[3] It ruptured along a thrust or reverse fault for 50 km. Because of its size and rupture length, this quake could be considered an independent mainshock.
The earthquake of October 18 was slightly more complex, consisting of two events separated by a time gap of 12 seconds. Two focal mechanisms were discovered during the mainshock thrust and strike-slip, which meant that there was a transition of faulting.[4] This quake ruptured a 90 km section of the fault.[5] A third event 100 seconds later could be part of the mainshock sequence.[6][7] It is believed that this earthquake was a result of slippage along the Murindó Fault, a left-lateral strike-slip fault, and other smaller structures. No surface rupture was ever mentioned in reports.
