Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S)
During the last few hundred years several destructive earthquakes occurred along the eastern margin of the Andean Precordillera, where GPS data reveal a shortening rate of ∼4.5 mm/a. We use fault scarp profiles and age determinations of deformed terraces (T<inf>1</inf>-T<inf>4</...
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2011
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v30_n5_p_Schmidt http://hdl.handle.net/20.500.12110/paper_02787407_v30_n5_p_Schmidt |
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paper:paper_02787407_v30_n5_p_Schmidt2023-06-08T15:26:53Z Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) Earthquakes Risk assessment Age determination Co-seismic displacement Fault dip Fault scarp GPS data Holocenes Seismic hazards Slip rates Thrust faults Landforms coseismic process displacement earthquake earthquake magnitude GPS Holocene mountain region seismic hazard slip rate thrust fault Precordillera Pisum sativum During the last few hundred years several destructive earthquakes occurred along the eastern margin of the Andean Precordillera, where GPS data reveal a shortening rate of ∼4.5 mm/a. We use fault scarp profiles and age determinations of deformed terraces (T<inf>1</inf>-T<inf>4</inf>) to infer coseismic displacements and quantify slip rates for the Peas and Cal thrust faults near Mendoza city. Scarps on the lowest terrace level T<inf>1</inf> reveal vertical offsets of 0.8-1.0 m for both faults, which are interpreted as coseismic displacements during the last earthquake. Together with the fault dip these offsets indicate that both faults are capable of producing magnitude M<inf>W</inf> ∼6.9 earthquakes, which is corroborated by a magnitude M <inf>S</inf> = 7.0 event on the Cal fault that destroyed Mendoza in 1861. At the Peas thrust fault, terrace T<inf>2</inf> has an age of ∼3.3 ka and is offset by ∼1.9 m, whereas the ∼12-ka-old terrace T<inf>3</inf> is displaced by ∼11 m. Combined with the fault dip of ∼25 °, the age and offset of terrace T<inf>3</inf> define a shortening rate of ∼2.0 mm/a on the Peas fault, i.e., about half of the present-day shortening at the eastern margin of the Precordillera. At the Cal fault, terraces T<inf>2</inf> to T <inf>4</inf> have ages of ∼0.8 ka (OSL), ∼3.9 ka (14C), and 12 ka (10Be) and are vertically offset by ∼2.6, ∼3.6, and ∼7.0 m, respectively, which implies that slip on the fault has recently accelerated. Hence, the Cal fault poses a serious seismic hazard to the one million inhabitants of Mendoza. Copyright 2011 by the American Geophysical Union. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v30_n5_p_Schmidt http://hdl.handle.net/20.500.12110/paper_02787407_v30_n5_p_Schmidt |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Earthquakes Risk assessment Age determination Co-seismic displacement Fault dip Fault scarp GPS data Holocenes Seismic hazards Slip rates Thrust faults Landforms coseismic process displacement earthquake earthquake magnitude GPS Holocene mountain region seismic hazard slip rate thrust fault Precordillera Pisum sativum |
| spellingShingle |
Earthquakes Risk assessment Age determination Co-seismic displacement Fault dip Fault scarp GPS data Holocenes Seismic hazards Slip rates Thrust faults Landforms coseismic process displacement earthquake earthquake magnitude GPS Holocene mountain region seismic hazard slip rate thrust fault Precordillera Pisum sativum Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| topic_facet |
Earthquakes Risk assessment Age determination Co-seismic displacement Fault dip Fault scarp GPS data Holocenes Seismic hazards Slip rates Thrust faults Landforms coseismic process displacement earthquake earthquake magnitude GPS Holocene mountain region seismic hazard slip rate thrust fault Precordillera Pisum sativum |
| description |
During the last few hundred years several destructive earthquakes occurred along the eastern margin of the Andean Precordillera, where GPS data reveal a shortening rate of ∼4.5 mm/a. We use fault scarp profiles and age determinations of deformed terraces (T<inf>1</inf>-T<inf>4</inf>) to infer coseismic displacements and quantify slip rates for the Peas and Cal thrust faults near Mendoza city. Scarps on the lowest terrace level T<inf>1</inf> reveal vertical offsets of 0.8-1.0 m for both faults, which are interpreted as coseismic displacements during the last earthquake. Together with the fault dip these offsets indicate that both faults are capable of producing magnitude M<inf>W</inf> ∼6.9 earthquakes, which is corroborated by a magnitude M <inf>S</inf> = 7.0 event on the Cal fault that destroyed Mendoza in 1861. At the Peas thrust fault, terrace T<inf>2</inf> has an age of ∼3.3 ka and is offset by ∼1.9 m, whereas the ∼12-ka-old terrace T<inf>3</inf> is displaced by ∼11 m. Combined with the fault dip of ∼25 °, the age and offset of terrace T<inf>3</inf> define a shortening rate of ∼2.0 mm/a on the Peas fault, i.e., about half of the present-day shortening at the eastern margin of the Precordillera. At the Cal fault, terraces T<inf>2</inf> to T <inf>4</inf> have ages of ∼0.8 ka (OSL), ∼3.9 ka (14C), and 12 ka (10Be) and are vertically offset by ∼2.6, ∼3.6, and ∼7.0 m, respectively, which implies that slip on the fault has recently accelerated. Hence, the Cal fault poses a serious seismic hazard to the one million inhabitants of Mendoza. Copyright 2011 by the American Geophysical Union. |
| title |
Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| title_short |
Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| title_full |
Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| title_fullStr |
Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| title_full_unstemmed |
Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (∼33°S) |
| title_sort |
coseismic displacements and holocene slip rates for two active thrust faults at the mountain front of the andean precordillera (∼33°s) |
| publishDate |
2011 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v30_n5_p_Schmidt http://hdl.handle.net/20.500.12110/paper_02787407_v30_n5_p_Schmidt |
| _version_ |
1768544728536580096 |