Repeated Folding during Late Holocene Earthquakes on the La Cal Thrust Fault near Mendoza City (Argentina)

Salomon E, Schmidt S, Hetzel R, Mingorance F, Hampel A (2013)

Publication Status: Published

Publication Type: Journal article

Publication year: 2013

Journal

Bulletin of the Seismological Society of America Seismological Society of America

Publisher: SEISMOLOGICAL SOC AMER

Book Volume: 103

Pages Range: 936-949

Journal Issue: 2A

DOI: 10.1785/0120110335

Abstract

In 1861, one of the most destructive earthquakes in the history of Argentina destroyed the city of Mendoza (currently 1 million inhabitants). The magnitude M-S similar to 7.0 earthquake is inferred to have occurred on the 31-km-long La Cal thrust fault, which extends from Mendoza to the north, where it offsets an alluvial fan and small inset terraces along a well-preserved fault scarp. A trench excavated on a terrace that is vertically offset by similar to 2.5 m exposes two main stratigraphic units separated by an erosional unconformity. The coarse-grained upper unit is deformed by three east-vergent folds (F-1-F-3). Retrodeformation of these folds yields total displacements of similar to 2.0 m, similar to 2.4 m, and similar to 0.5 m on the underlying fault splays, respectively. The displacement of similar to 2.0 m recorded by fold F-1 is interpreted as the result of the fault rupture that caused the 1861 earthquake. F-2 and F-3 were presumably generated during the penultimate event with an inferred magnitude of M-w similar to 7.0, although formation during two distinct ruptures cannot be excluded. Finite-element modeling shows that coseismic folding above the tip of a blind thrust fault is a physically plausible mechanism to generate these folds. A published luminescence age of 770 +/- 76 years, which is interpreted to date the formation of the deformed terrace, indicates that the two (or possibly three) scarp-forming events occurred during the last similar to 800 years. The fine-grained sediments below the erosional unconformity-that contain evidence for at least one older earthquake-are dated at similar to 12 kyr. Our results indicate that elastic strain energy, which is accumulating at the front of the Precordillera today as shown by Global Positioning System (GPS) data, was repeatedly released during earthquakes on the La Cal fault in the past. Hence, the La Cal thrust fault poses a serious threat to the city of Mendoza.

Authors with CRIS profile

Eric Salomon Lehrstuhl für Geologie (Exogene Dynamik)

Involved external institutions

Gottfried Wilhelm Leibniz Universität Hannover DE Germany (DE) Universidad Nacional de Cuyo AR Argentina (AR) Westfälische Wilhelms-Universität (WWU) Münster DE Germany (DE)

How to cite

APA:

Salomon, E., Schmidt, S., Hetzel, R., Mingorance, F., & Hampel, A. (2013). Repeated Folding during Late Holocene Earthquakes on the La Cal Thrust Fault near Mendoza City (Argentina). Bulletin of the Seismological Society of America, 103(2A), 936-949. https://dx.doi.org/10.1785/0120110335

MLA:

Salomon, Eric, et al. "Repeated Folding during Late Holocene Earthquakes on the La Cal Thrust Fault near Mendoza City (Argentina)." Bulletin of the Seismological Society of America 103.2A (2013): 936-949.

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