Source study and tectonic implications of the historic 1958 Las Melosas crustal earthquake, Chile, compared to earthquake damage

Alvarado, Patricia; Barrientos, Sergio; Sáez, Mauro; Astroza, Maximiliano; Beck, S. L.

doi:10.1016/j.pepi.2008.03.015

Cited by 36 publications

(36 citation statements)

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“…Eventually active strike-slip faulting along N-S trending structures could accommodate deformation further west in the forearc and intra-arc Andean regions although this type of seismicity has not been instrumentally recorded yet. Clear analogies to these alternative fault systems and seismicity exist in other seismic Andean segments (Cembrano et al, 2007;Lange et al, 2008;Alvarado et al, 2009b) and the Sumatran subduction zone (McCaffrey, 2009). In those margins, significant continental faults accommodate slip partition in the forearc region such as the forearc Liquiñe-Ofqui Andean Fault or the Sumatran Fault.…”

Section: Discussionmentioning

confidence: 99%

Earthquake deformation in the northwestern Sierras Pampeanas of Argentina based on seismic waveform modelling

Alvarado

Ramos

2011

Journal of Geodynamics

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Section: Discussionmentioning

confidence: 99%

Earthquake deformation in the northwestern Sierras Pampeanas of Argentina based on seismic waveform modelling

Alvarado

Ramos

2011

Journal of Geodynamics

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“…Taking an average thrust slip ranging between 1 and 4 m over the 15 km long piedmont fault segment with rupture width of 15 km (corresponding to the frontal ramp in Figure 3c, breaking from 10 km depth to the surface) would yield seismic moments of M o ∼0.75 to 3 × 10 19 N m, corresponding to events of magnitude M w 6.6 to M w 7.0. This range of magnitudes is higher than that of the sequence of three consecutive shocks, all together known as the 1958, Las Melosas earthquake, which correspond to the largest events recorded instrumentally in the upper plate near Santiago [see Sepúlveda et al , 2008; Alvarado et al , 2009, and references therein]. The 1958 sequence occurred within an interval of 6 min with hypocentral depth of 10 km in the center of the Principal Cordillera ∼60 km SE of Santiago, with intensity values reaching IX in the epicentral area.…”

Section: San Ramón Faultmentioning

confidence: 99%

The West Andean Thrust, the San Ramón Fault, and the seismic hazard for Santiago, Chile

et al. 2010

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The importance of west verging structures at the western flank of the Andes, parallel to the subduction zone, appears currently minimized. This hampers our understanding of the Andes‐Altiplano, one of the most significant mountain belts on Earth. We analyze a key tectonic section of the Andes at latitude 33.5°S, where the belt is in an early stage of its evolution, with the aim of resolving the primary architecture of the orogen. We focus on the active fault propagation–fold system in the Andean cover behind the San Ramón Fault, which is critical for the seismic hazard in the city of Santiago and crucial to decipher the structure of the West Andean Thrust (WAT). The San Ramón Fault is a thrust ramp at the front of a basal detachment with average slip rate of ∼0.4 mm/yr. Young scarps at various scales imply plausible seismic events up to Mw 7.4. The WAT steps down eastward from the San Ramón Fault, crossing 12 km of Andean cover to root beneath the Frontal Cordillera basement anticline, a range ∼5 km high and >700 km long. We propose a first‐order tectonic model of the Andes involving an embryonic intracontinental subduction consistent with geological and geophysical observations. The stage of primary westward vergence with dominance of the WAT at 33.5°S is evolving into a doubly vergent configuration. A growth model for the WAT‐Altiplano similar to the Himalaya‐Tibet is deduced.Wesuggest that the intracontinental subduction at theWAT is amechanical substitute of a collision zone, rendering the Andean orogeny paradigm obsolete.Our work has been supported by the binational French‐Chilean ECOS‐Conicyt program (project C98U02), the French Agence Nationale pour la Recherche, Project Sub Chile (ANR‐05‐ CATT‐014), and the Chilean ICM project “Millennium Science Nucleus of Seismotectonics and Seismic Hazard,

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“…Quaternary faults have been proposed to trigger many of the rock avalanches (Moreiras 2006(Moreiras , 2009b. In Chile, Antinao & Gosse (2009) prepared a large landslide inventory and suggested a relationship with regional faults and seismicity, yet only one historic earthquake in 1958 (M w 6.3, Alvarado et al 2009) triggered landslides and these were only of medium to large size (volume of a few millions of cubic metres; Sepúlveda et al 2008). In this context, a major question is whether huge palaeo-landslide deposits observed throughout the Andean region are linked to seismic activity or climatic events, that is, whether these deposits can be used as unambiguous indicators of tectonic or climatic forcing.…”

Section: Quaternary Tectonics and Geohazardsmentioning

confidence: 99%

Geodynamic processes in the Andes of Central Chile and Argentina: an introduction

Sepúlveda

Giambiagi

Moreiras

et al. 2014

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The Andes, the world's largest non-collisional orogen, is considered the paradigm for geodynamic processes associated with the subduction of an oceanic plate below a continental plate margin. In the framework of UNESCO-sponsored IGCP 586-Y project, this Special Publication includes state-of-the-art reviews and original articles from a range of Earth Science disciplines that investigate the complex interactions of tectonics and surface processes in the subductionrelated orogen of the Andes of central . This introduction provides the geological context of the transition from flat slab to normal subduction angles, where this volume is focused, along with a brief description of the individual contributions ranging from internal geodynamics and tectonics, Quaternary tectonics and related geohazards, to landscape evolution of this particular segment of the Andes.Convergent continental margins are one of the firstorder expressions of the movement of Earth's tectonic plates atop a convecting mantle. The topography of convergent margins is due to the interactions of rock uplift, climate and surface processes that are dominantly driven by upper crustal and internal lithospheric deformation as well as erosional processes (e.g. Molnar & Lyon-Caen 1988;Beaumont et al. 2004;Whipple & Meade 2006). The Andes of central Chile and Argentina (c. 32 -368S, Figs 1 & 2) straddle a potentially important transition in geodynamic boundary conditions imposed on the upper plate: a drastic change in the geometry of the subducting Nazca plate from 'flat' to normal subduction angles, from c. 5-108 to 308 (Cahill & Isacks 1992; Fig. 1). This segment of the Andes is therefore a particularly suitable setting to evaluate the interplay between constructive deep mechanisms, resulting in rock uplift and lateral expansion of the Andes, and the mechanisms of exhumation and erosion that shape the landscape in an active, convergent margin.The Central Andes are composed of different morphostructural units (from west to east; Figs 1 & 2): the Chilean Coastal Cordillera, the Principal Cordillera (spanning Chile and Argentina), the Frontal Cordillera, the Argentine Precordillera and the Pampean Ranges (Jordan et al. 1983). Although previous studies attempt to constrain the magnitudes of orogenic shortening for each morphostructural unit, limited amounts of geochronology complicate attempts to constrain more tightly the rates of shortening and topographic uplift. There are several outstanding questions regarding the interplay between deep and surface processes in the development of the Andean Orogen over different timescales, as follows. † What is the nature of the interaction between tectonic and surface processes in this sector of the Andes? In particular, are surface and tectonic processes part of a strongly coupled system? † What control does the geometry of the subducting slab exert over the timing and style of deformation in the South American plate? † How do deformation and denudation evolve in space and time? Are there differences between ...

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Source study and tectonic implications of the historic 1958 Las Melosas crustal earthquake, Chile, compared to earthquake damage

Cited by 36 publications

References 57 publications

Earthquake deformation in the northwestern Sierras Pampeanas of Argentina based on seismic waveform modelling

Earthquake deformation in the northwestern Sierras Pampeanas of Argentina based on seismic waveform modelling

The West Andean Thrust, the San Ramón Fault, and the seismic hazard for Santiago, Chile

Geodynamic processes in the Andes of Central Chile and Argentina: an introduction

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