1946 Ancash earthquake

1946 Ancash earthquake
UTC time	1946-11-10 17:42:56
ISC event	898660
USGS-ANSS	ComCat
Local date	November 10, 1946
Local time
Magnitude	6.8 Mw; 7.3
Depth	15-17 km
Epicenter	8.410°S 77.535°W
Type	Dip-slip
Areas affected	Central Peru
Max. intensity	XI (Extreme)
Tsunami	None
Landslides	Numerous
Casualties	~1,400[1]

The 1946 Ancash earthquake in the Andes Mountains of central Peru occurred at 17:43 UTC on November 10. The earthquake had a magnitude of 7.3, and achieved a Mercalli intensity scale rating of XI (Extreme).[2] About 1,400 Peruvians are thought to have died from the event.[1]

Earthquake

It was triggered by slippage along a normal fault at a depth of ~17.0 km with a magnitude of 6.9-7.3, as suggested by the focal mechanism. The fault was a shallow crustal structure on the South American Plate, as surface ruptures were observed with a maximum offset of 3.5 meters. This event also reactivated several older thrust faults.[3] These faults are part of the Marańón Thrust and Fold Belt, which formed in the Tertiary. The surface rupture from this quake ran for 21 km.[1]

Effects

Many landslides were triggered by the very strong ground motions which was the reason for the high death toll and destruction. One of these slides completely buried the village of Acobamba in Suytucocha Valley.[4]

References

Bellier, Olivier; Dumont, Jean Francois; Sebrier, Michel; Mercier, Jacques Louis (April 1991). "Geological constraints on the kinematics and fault-plane solution of the Quiches Fault Zone reactivated during the 10 November 1946 Ancash earthquake, northern Peru". Bulletin of the Seismological Society of America. 81: 468–490.
"Significant Earthquake Information PERU: JOCAIBAMBA,CERRO ANGASCHAJ,CERRO SILLAPATA". NGDC. Retrieved 12 Dec 2020.
Diane I. Doser (October 1987). "The Ancash, Peru, earthquake of 1946 November 10: evidence for low-angle normal faulting in the high Andes of northern Peru". Geophysical Journal International. 91: 57–71. doi:10.1111/j.1365-246X.1987.tb05213.x.
Kampherm, Tanya Sandra. Landslides triggered by the 1946 Ancash Earthquake (Peru) and geologic controls on the mechanisms of initial rock slope failure (Dissertation). OCLC 827757776.

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[Bellier_etal_1991-1] Bellier, Olivier; Dumont, Jean Francois; Sebrier, Michel; Mercier, Jacques Louis (April 1991). "Geological constraints on the kinematics and fault-plane solution of the Quiches Fault Zone reactivated during the 10 November 1946 Ancash earthquake, northern Peru". Bulletin of the Seismological Society of America. 81: 468–490.

[2] "Significant Earthquake Information PERU: JOCAIBAMBA,CERRO ANGASCHAJ,CERRO SILLAPATA". NGDC. Retrieved 12 Dec 2020.

[3] Diane I. Doser (October 1987). "The Ancash, Peru, earthquake of 1946 November 10: evidence for low-angle normal faulting in the high Andes of northern Peru". Geophysical Journal International. 91: 57–71. doi:10.1111/j.1365-246X.1987.tb05213.x.

[4] Kampherm, Tanya Sandra. Landslides triggered by the 1946 Ancash Earthquake (Peru) and geologic controls on the mechanisms of initial rock slope failure (Dissertation). OCLC 827757776.