Map and database of Quaternary faults in Bolivia and Chile

Lavenu, Alain; Thiele, Ricardo; Machette, Michael N.; Dart, Richard L.; Bradley, Lee‐Ann; Haller, Kathleen M.

doi:10.3133/ofr00283

Cited by 18 publications

(21 citation statements)

References 4 publications

(13 reference statements)

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“…The M w 6.1 Parina earthquake occurred in a region of south Peru that has experienced a number of recent M w 5.0-5.8 normal-faulting earthquakes (Cabrera & Sebrier, 1998;Devlin et al, 2012;Dziewonski et al, 1981;Ekström et al, 2012;Jay et al, 2015; Figure 1a). Geomorphic evidence of recent normal faulting in the Journal of Geophysical Research: Solid Earth 10.1029/2018JB015588 epicentral region is scarce (e.g., Benavente et al, 2013) but has been documented further north near Cuzco (Benavente et al, 2013;Mercier et al, 1992;Sébrier et al, 1985;Suarez et al, 1983), and to the south near Arequipa (Lavenu et al, 2000). The limited geomorphic expression of normal faults in south Peru probably reflects the small amount of finite extensional strain in the high mountains (< 1%; Sébrier et al, 1985).…”

Section: The 1 December 2016 Parina Earthquakementioning

confidence: 99%

“…Geological evidence of recent normal faulting in the high Andes is widespread, with examples of extensional structures in regions at elevations >3,000 m from central and southern Peru (Benavente et al, 2013;Dalmayrac & Molnar, 1981;Kar et al, 2016;Mercier et al, 1992;Sébrier et al, 1985Sébrier et al, , 1988Veloza et al, 2012), northern Chile (Tibaldi & Bonali, 2018;Tibaldi et al, 2009), southern and northern Bolivia (Lamb, 2000;Lavenu et al, 2000;Mercier, 1981), and northern Argentina (Cladouhos et al, 1994;Lavenu et al, 2000;Marrett et al, 1994;Schoenbohm & Strecker, 2009;Figures 9a and 13). The timing of motion on these normal faults can be bracketed by cross-cutting relationships with the extensive volcanics erupted continually throughout the Andean orogeny.…”

Section: Late Miocene Change In the Dynamics Of The Andesmentioning

confidence: 99%

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Extension and Dynamics of the Andes Inferred From the 2016 Parina (Huarichancara) Earthquake

et al. 2018

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The Mw 6.1 2016 Parina earthquake led to extension of the south Peruvian Andes along a normal fault with evidence of Holocene slip. We use interferometric synthetic aperture radar, seismology, and field mapping to determine a source model for this event and show that extension at Parina is oriented NE‐SW, which is parallel to the shortening direction in the adjacent sub‐Andean lowlands. In addition, we use earthquake source models and GPS data to demonstrate that shortening within the sub‐Andes is parallel to topographic gradients. Both observations imply that forces resulting from spatial variations in gravitational potential energy are important in controlling the geometry of the deformation in the Andes. We calculate the horizontal forces per unit length acting between the Andes and South America due to these potential energy contrasts to be 4–8 ×1012 N/m along strike of the mountain range. Normal faulting at Parina implies that the Andes in south Peru have reached the maximum elevation that can be supported by the forces transmitted across the adjacent foreland, which requires that the foreland faults have an effective coefficient of friction ≲0.2. Additionally, the onset of extension in parts of the central Andes following orogen‐wide compression in the late Miocene suggests that there has been a change in the force balance within the mountains. We propose that shortening on weak detachment faults within the Andean foreland since ∼5–9 Ma reduced the shear tractions acting along the base of the upper crust in the eastern Andes, leading to extension in the highest parts of the range.

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Section: The 1 December 2016 Parina Earthquakementioning

confidence: 99%

Section: Late Miocene Change In the Dynamics Of The Andesmentioning

confidence: 99%

Extension and Dynamics of the Andes Inferred From the 2016 Parina (Huarichancara) Earthquake

et al. 2018

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“…Despite these results and evidence, including newly identified faulted late Holocene surfaces, of recent activity across multiple wedge‐front faults [ Brooks et al ., , ; Lavenu et al ., ], there is no historical earthquake record of earthquakes > M w 5 associated with the frontal fault system. Other than an analysis of the morphology of the range‐crossing Rio Pilcomayo to infer recent thrust fault activity [ Mugnier et al ., ] and the identification of eroding hanging wall terraces in a few satellite images [ Lamb , ], no detailed neotectonic studies exist.…”

Section: Tectonic Setting and Previous Workmentioning

confidence: 99%

Spatial and temporal distribution of deformation at the front of the Andean orogenic wedge in southern Bolivia

et al. 2015

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New observations from an active orogenic wedge help link the seismotectonic behavior of individual faults to wedge deformation rates and patterns over multiple timescales. We provide the first detailed constraints on the distribution and timing of deformation at the front of the Andean orogenic wedge in southern Bolivia, where a recent study suggests that great (M w > 8) earthquakes could rupture the master fault underlying the wedge. We use stratigraphic relationships across fault-related folds and elastic dislocation modeling of seismic reflection horizons to obtain probabilistic estimates of wedge-front fault ages and slip rates. Our analyses reveal that at least half of the previously determined GPS-based wedge-loading and Quaternary whole-wedge shortening rates are absorbed across a 20-40 km wide wedge-front zone consisting of 1-4 en echelon and partially to fully overlapping faults and folds associated with blind thrust faults. The difference between our slip rates and the geodetic/geologic observations combined with evidence for activity across internal wedge structures supports the notion that nonsteady state mass balance conditions coupled with elevated erosional efficiency result in distributed wedge deformation. The orogenic wedge in southern Bolivia behaves in a similar fashion to the Taiwanese and Himalayan ranges; slip accumulates at downdip locations along the master fault and is released incrementally by earthquakes that rupture the wedge-front fault zone. The faults and folds comprising this zone pose a major source of seismic hazard. Accumulating slip is also released in the wedge interior and older, internal wedge faults must be considered in any future assessment of regional earthquake risk.

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“…The selection of active faults in the western part of the Alps orogen (from among many mapped faults) was based on the work by Battaglia et al [2004], geodetic results of Anzidei et al [2001], and stress data of Montone et al [2004]. Active faults in the Peru and Altiplano‐Sierras Pampeanas orogens of the Andes are from Lavenu et al [2000], Costa et al [2000], and Macharé et al [2003]. Another general reference was a preliminary version of International Lithosphere Program II‐2 World Map of Major Active Faults [e.g., Mörner et al , 2004].…”

Section: Model Constructionmentioning

confidence: 99%

Stresses that drive the plates from below: Definitions, computational path, model optimization, and error analysis

2008

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[1] We divide the torques on each surface plate into three parts: lithostatic pressure, side strength, and basal strength. We compute each part for each of 52 plates using a thin shell finite element model of the lithosphere with topography, variable heat flow, variable crust and lithosphere thicknesses from seismic data, transient geotherms, nonlinear rheology, and weak faults. We present an iterative method of adjusting boundary conditions that results in correct plate velocities without the need for models of deep mantle flow. Uncertainty remains because side strength torques, and therefore inferred basal strength torques, depend on the effective friction of faults. Therefore, we compute a two-parameter suite of models with differing trench resistance and differing fault friction, and we evaluate their misfits relative to seafloor spreading rates, geodetic velocities, intraplate stress directions, and azimuths of seismic anisotropy. The minimum misfit occurs at effective fault friction of 0.1 and trench resistance of 2 Â 10 12 N m À1 . In this preferred model, computed values of mean basal strength traction systematically increase for smaller plates. We analyze error sources and find that the largest source is unmodeled variation in effective friction of plate boundary faults. Discounting highly uncertain results, we find mean basal shear tractions of no more than 1 MPa for the six largest slabless plates: Africa 0.2 MPa; Antarctica 0.1 MPa; North America 0.6 MPa; Eurasia 1.0 MPa; South America 1.0 MPa; Somalia 0.9 MPa. The directions of basal shear traction on these plates are generally forward, meaning subparallel to absolute velocity. Basal strength torques on plates with subducting slabs represent the sum of net slab pull and distributed basal shear traction; if these torques are attributed to net slab pull alone, net slab pull is generally toward the trench and of order 5 Â 10 12 N m À1 . Thus, present plate motions on Earth appear to be driven primarily by deep mantle convection rather than by topography and associated lithostatic pressures.Citation: Bird, P., Z. Liu, and W. K. Rucker (2008), Stresses that drive the plates from below: Definitions, computational path, model optimization, and error analysis,

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Map and database of Quaternary faults in Bolivia and Chile

Cited by 18 publications

References 4 publications

Extension and Dynamics of the Andes Inferred From the 2016 Parina (Huarichancara) Earthquake

Extension and Dynamics of the Andes Inferred From the 2016 Parina (Huarichancara) Earthquake

Spatial and temporal distribution of deformation at the front of the Andean orogenic wedge in southern Bolivia

Stresses that drive the plates from below: Definitions, computational path, model optimization, and error analysis

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