Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic<sup>10</sup>Be and optically stimulated luminescence determinations

A., J. Cortés; L., Gabriel González; Binnie, Steven A.; Robinson, R. W.; Freeman, Stewart P.H.T.; E., G. Vargas

doi:10.1029/2011tc002877

Cited by 40 publications

(42 citation statements)

References 79 publications

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“…Marine terraces typically date from about 800 ka to <10 ka [Regard et al, 2010] (see Figure 1a and Table S1 for references). Recent efforts in surveying and dating these coastal features using in situ produced cosmogenic nuclide exposure dating have provided robust constraints on the rates and patterns of local coastal uplift along most of the coast of Peru and Chile [Marquardt et al, 2004;Quezada et al, 2007;Saillard, 2008;Melnick et al, 2009;Saillard et al, 2009Saillard et al, , 2011Cortès et al, 2012;Jara-Muñoz et al, 2015]. These data reveal spatiotemporally variable uplift rates along and across strike during the last million years [Saillard et al, 2009[Saillard et al, , 2012 (Figure 1a).…”

Section: Long-term Coastal Dynamics Of the Andean Marginmentioning

confidence: 96%

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

et al. 2017

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Measurement of interseismic strain along subduction zones reveals the location of both locked asperities, which might rupture during megathrust earthquakes, and creeping zones, which tend to arrest such seismic ruptures. The heterogeneous pattern of interseismic coupling presumably relates to spatial variations of frictional properties along the subduction interface and may also show up in the fore‐arc morphology. To investigate this hypothesis, we compiled information on the extent of earthquake ruptures for the last 500 years and uplift rates derived from dated marine terraces along the South American coastline from central Peru to southern Chile. We additionally calculated a new interseismic coupling model for that same area based on a compilation of GPS data. We show that the coastline geometry, characterized by the distance between the coast and the trench; the latitudinal variations of long‐term uplift rates; and the spatial pattern of interseismic coupling are correlated. Zones of faster and long‐term permanent coastal uplift, evidenced by uplifted marine terraces, coincide with peninsulas and also with areas of creep on the megathrust where slip is mostly aseismic and tend to arrest seismic ruptures. We conclude that spatial variations of frictional properties along the megathrust dictate the tectono‐geomorphological evolution of the coastal zone and the extent of seismic ruptures along strike.

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Section: Long-term Coastal Dynamics Of the Andean Marginmentioning

confidence: 96%

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

et al. 2017

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“…[47] Why were other preexisting intraplate faults not triggered by the Maule earthquake, at least with magnitudes large enough for focal mechanisms to be calculated? In northern Chile, recent work by Cortés et al [2012] suggests that upper plate fore-arc normal faults have recurrence intervals more than one order of magnitude longer than the plate boundary seismic cycle. Thus, if subduction earthquakes are responsible for the permanent upper plate extension, many cycles are necessary to accumulate shear loading and break the Coastal Cordillera or reactivate upper plate normal faults.…”

Section: Breaking the Fore Arcmentioning

confidence: 99%

Permanent fore‐arc extension and seismic segmentation: Insights from the 2010 Maule earthquake, Chile

et al. 2013

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[1] Geologists have long known that young normal faults are an important structural element of the Andean Coastal Cordillera, but their relationship to the subduction seismic cycle is still unclear. Some of the largest aftershocks of the 2010 M w 8.8 Maule earthquake in central Chile were nucleated on upper plate normal faults, including the M w 6.9 and 7.0 events of the Pichilemu earthquake sequence. We use the available coseismic GPS displacements, moment tensor sums, and slip distribution models for the Maule earthquake to compute the static strain and stress fields imposed on the upper plate by slip on the subduction interface. The extensional strains calculated from coseismic GPS and from a moment tensor sum of the Pichilemu events have similar orientations and orders of magnitude. The normal Coulomb stress increment (CSI) on the Pichilemu fault has maximum positive stresses as high as 4.9 MPa. Regionally, the Maule event produced a semi-elliptical, radial pattern of static extension and deviatoric tension (CSI > 1.5 MPa) along the Coastal Cordillera enclosing the rupture area. This elliptical pattern mimics the trends of the major upper-crustal structures. The static deformation field produced by a great subduction earthquake is an effective mechanism for generating permanent extension above the seismogenic zone, reactivating suitably oriented, long-lived normal faults. We suggest that the semi-elliptical outline of the first-order structures along the Coastal Cordillera may define the location of a characteristic, long-lived megathrust segment. This observation implies a persistence at least over the Quaternary of great subduction ruptures along the Maule segment.

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“…(Cortés et al, 2012). Therefore, the period of great drought in coastal northern Chile probably spread between 14,000 and 5,400 yr B.P., followed by a semi-arid period, and again by hyper-arid conditions lasting until present.…”

Section: Climatic History During the Late Pleistoceneholocene In The mentioning

confidence: 99%

Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta.

Herrera

Custódio

2014

Andgeo

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ABSTRACT. The origin of waters from small springs located at the hyper-arid northern coast of Chile, in the vicinity of Antofagasta, is discussed after hydrogeochemical and isotopic studies and supported by groundwater flow hydrodynamic considerations. Spring water is brackish to saline, with electrical conductivity ranging from 2 to 25 mS/cm. Chemical and water isotope data ( 18 O and 2 H) show that the rainfall events that produced part of the recharge could correspond to wetter conditions than at present. Their origin could be related to the emplacement of warm sea currents facing the coast of northern Chile, possibly associated to incursions of El Niño Southern Oscillation (ENSO). Radiocarbon dating and preliminary groundwater hydraulic calculations indicate that these spring waters could be remnants of a more significant recharge in the Cordillera de la Costa than that produced today during the less arid period about 5,000 to 3,000 years ago. The exception is Las Vertientes spring which is the only one that receives water transferred from the Central Depression. The springs are the visible discharge of a regional groundwater body in the very low permeability Cordillera de la Costa, whose hydraulic conductivity decreases downward and flow is dominantly though fissures and storage in the low porosity rock matrix. Costa, Antofagasta, Spring, Groundwater, Stable isotopes, Radiocarbon, Arid climate, Recharge. RESUMEN. Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta. Se discute el origen de las aguas que surgen en pequeños manantiales localizados en la costa hiperárida del norte de Chile a partir de un estudio hidrogeoquímico e isotópico, apoyado en consideraciones hidrodinámicas del flujo del agua subterránea. Las aguas de los manantiales son salobres a salinas, con valores de la conductividad eléctrica que varían entre 2 y 25 mS/cm. El estudio de la composición química e isotópica ( 18 O y 2 H) de las aguas revela que las precipitaciones que produjeron la recarga se registraron en condiciones más húmedas que en la actualidad. Su origen estaría relacionado con el emplazamiento de corrientes marinas cálidas frente a las costas del norte de Chile, posiblemente asociadas a la incursión de El Niño-Oscilación del Sur (ENOS). Las dataciones con radiocarbono y los cálculos hidráulicos preliminares indican que las aguas que afloran en estos manantiales pueden corresponder a remanentes de una recarga más significativa ocurrida en un período menos árido que el actual alrededor de 5.000 a 3.000 años atrás, si bien también hay evidencia de alguna recarga reciente en situaciones locales. La única excepción corresponde a las aguas del manantial de Las Vertientes, que recibe contribución de aguas subterráneas de la depresión Central. Los manantiales son la descarga visible de un cuerpo general de agua subterránea en los materiales muy poco permeables de la Cordillera de la Costa, cuya conductividad hidráulica decrece en profundidad y donde el flujo se produce domin...

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Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic¹⁰Be and optically stimulated luminescence determinations

Cited by 40 publications

References 79 publications

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

Permanent fore‐arc extension and seismic segmentation: Insights from the 2010 Maule earthquake, Chile

Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta.

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Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic10Be and optically stimulated luminescence determinations

Cited by 40 publications

References 79 publications

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

Permanent fore‐arc extension and seismic segmentation: Insights from the 2010 Maule earthquake, Chile

Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta.

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Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic¹⁰Be and optically stimulated luminescence determinations