Details
| Original language | English |
|---|---|
| Pages (from-to) | 936-949 |
| Number of pages | 14 |
| Journal | Bulletin of the Seismological Society of America |
| Volume | 103 |
| Issue number | 2 A |
| Publication status | Published - Apr 2013 |
Abstract
In 1861, one of the most destructive earthquakes in the history of Argentina destroyed the city of Mendoza (currently 1 million inhabitants). The magnitudeMS ~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 ~2.5 m exposes two main stratigraphic units separated by an erosional unconformity. The coarse-grained upper unit is deformed by three eastvergent folds (F1-F3). Retrodeformation of these folds yields total displacements of ~2.0 m,~2.4 m, and~0.5 mon the underlying fault splays, respectively. The displacement of ~2.0 m recorded by fold F1 is interpreted as the result of the fault rupture that caused the 1861 earthquake. F2 and F3 were presumably generated during the penultimate event with an inferred magnitude of Mw ~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.Apublished 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 ~800 years. The fine-grained sediments below the erosional unconformity-that contain evidence for at least one older earthquake- are dated at ~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.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Bulletin of the Seismological Society of America, Vol. 103, No. 2 A, 04.2013, p. 936-949.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Repeated folding during late holocene earthquakes on the La Cal thrust fault near Mendoza City (Argentina)
AU - Salomon, Eric
AU - Schmidt, Silke
AU - Hetzel, Ralf
AU - Mingorance, Francisco
AU - Hampel, Andrea
PY - 2013/4
Y1 - 2013/4
N2 - In 1861, one of the most destructive earthquakes in the history of Argentina destroyed the city of Mendoza (currently 1 million inhabitants). The magnitudeMS ~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 ~2.5 m exposes two main stratigraphic units separated by an erosional unconformity. The coarse-grained upper unit is deformed by three eastvergent folds (F1-F3). Retrodeformation of these folds yields total displacements of ~2.0 m,~2.4 m, and~0.5 mon the underlying fault splays, respectively. The displacement of ~2.0 m recorded by fold F1 is interpreted as the result of the fault rupture that caused the 1861 earthquake. F2 and F3 were presumably generated during the penultimate event with an inferred magnitude of Mw ~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.Apublished 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 ~800 years. The fine-grained sediments below the erosional unconformity-that contain evidence for at least one older earthquake- are dated at ~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.
AB - In 1861, one of the most destructive earthquakes in the history of Argentina destroyed the city of Mendoza (currently 1 million inhabitants). The magnitudeMS ~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 ~2.5 m exposes two main stratigraphic units separated by an erosional unconformity. The coarse-grained upper unit is deformed by three eastvergent folds (F1-F3). Retrodeformation of these folds yields total displacements of ~2.0 m,~2.4 m, and~0.5 mon the underlying fault splays, respectively. The displacement of ~2.0 m recorded by fold F1 is interpreted as the result of the fault rupture that caused the 1861 earthquake. F2 and F3 were presumably generated during the penultimate event with an inferred magnitude of Mw ~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.Apublished 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 ~800 years. The fine-grained sediments below the erosional unconformity-that contain evidence for at least one older earthquake- are dated at ~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.
UR - http://www.scopus.com/inward/record.url?scp=84875409552&partnerID=8YFLogxK
U2 - 10.1785/0120110335
DO - 10.1785/0120110335
M3 - Article
AN - SCOPUS:84875409552
VL - 103
SP - 936
EP - 949
JO - Bulletin of the Seismological Society of America
JF - Bulletin of the Seismological Society of America
SN - 0037-1106
IS - 2 A
ER -