Structure and State of Stress of the Chilean Subduction Zone from Terrestrial and Satellite-Derived Gravity and Gravity Gradient Data

Gutknecht, Benjamin D.; Götze, Hans‐Jürgen; Jahr, T.; Jentzsch, G.; Mahatsente, R.; Zeumann, St

doi:10.1007/s10712-014-9296-9

Cited by 20 publications

(11 citation statements)

References 55 publications

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“…In addition to the presence of this rock unit with higher density than the surrounding rocks, the topographic load of the positive relief of the Nicoya Peninsula, located on top of the seismogenic zone, contributes to the increase in vertical stress due to the lithostatic load and the frictional state of the plate interface. The correlation between coupled zones on the seismogenic zone and geological bodies of high density (characterized by positive gravity anomalies and cause positive stress anomalies) is consistent with results by Sobiesiak et al (2007), Tassara (2010) and Gutknecht et al (2014) for the Chilean convergent margin.…”

Section: Discussionsupporting

confidence: 87%

“…The combined effect of the lithostatic pressure (σ v ) exerted by several layers at a depth of "z" below the geoid, taking into account the topographic load caused by masses that reach a height of "h" above the geoid is described in equation 2, after Gutknecht et al (2014):…”

Section: Calculation Of Static Stressmentioning

confidence: 99%

“…Equation 4 from Gutknecht et al (2014), shows how this component is calculated for a model with "n" amount of layers and accounting for the effect of topography. The geometry of the plate interface is reflected in the dip angle (α) of the subduction zone.…”

Section: Calculation Of Static Stressmentioning

confidence: 99%

“…The value of the reference density (ρ r ) is defined in order to eliminate the global effect of the depth gradient, which tends to mask the lateral heterogeneities of the stress field. In contrast with Gutknecht et al (2014), a single reference density was used, since in this research, the focus of the calculation of stress anomalies is on the effects of these anomalies on the seismogenic zone. Thus, a density of 3.32 g/cm 3 was chosen as reference since it was determined that it optimally removed the effect of the depth gradient for the shallower 50 km of the subduction zone.…”

Section: Calculation Of Static Stressmentioning

confidence: 99%

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Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

Lücke¹

2015

Rev. Geol. Amér. Central

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ABSTRACT:The forearc region along the Central American Subduction Zone shows a series of trench-parallel positive gravity anomalies with corresponding gravity lows along the trench and toward the coast. These features extend from Guatemala to northern Nicaragua. However, the Costa Rican section of the forearc does not follow this pattern due to the segmentation of the along-trench gravity low, the absence of the coastal low, and the presence of emerged continental mass along the forearc gravity high at the Nicoya Peninsula. Geodetic and seismological studies along the Costa Rican Subduction Zone suggest the presence of coupled areas in the seismogenic zone beneath the Nicoya Peninsula prior to the 7.6 Mw magnitude earthquake of September 5th, 2012. These areas have previously been associated with asperities. Based on the structure of the overriding plate, former publications have proposed a mechanical model for the origin of asperities along the Chilean convergent margin, in which the dense igneous material in the forearc of the overriding plate above the seismogenic zone modifies/disturbs the state of static stress and influences seismogenic processes. In Costa Rica, surface geology and gravity data indicate the existence of dense basalt/gabbro crust overlying the seismogenic zone where the coupling is present. Bouguer anomaly values in this region reach up to 120×10 -5 m/s 2 and are the highest for Costa Rica. In this research, the state of static stress on the Cocos-Caribbean plate interface is calculated based on the geometry and on the density distribution of a 3D litosphere density model of the subduction zone as interpreted from gravity data from combined geopotential models. Results show a spatial correlation between the coupled areas at the Nicoya Peninsula and the presence of anomalies on the static state of stress on the plate interface. The stress anomalies were calculated for the normal component of the vertical stress on the seismogenic zone and were interpreted as being generated by the dense material which makes up the forearc in the area.

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Section: Discussionsupporting

confidence: 87%

Section: Calculation Of Static Stressmentioning

confidence: 99%

Section: Calculation Of Static Stressmentioning

confidence: 99%

Section: Calculation Of Static Stressmentioning

confidence: 99%

See 2 more Smart Citations

Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

Lücke¹

2015

Rev. Geol. Amér. Central

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“…The spatial resolution of the Earth Gravitational Models (e.g., EGM2008, EIGEN-6C4) depends on the availability of high-quality land gravity data (Köther et al, 2012;Gutknecht et al, 2014;Godin and Harris, 2014). We would like to emphasize that the land gravity data in the EIGEN-6C4 model are based on the Earth Gravitational Model (EGM2008; Pavlis et al, 2012), which includes all available land gravity data.…”

Section: Gravity Databasementioning

confidence: 99%

Lithospheric structure and the isostatic state of Eastern Anatolia: Insight from gravity data modelling

2018

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Eastern Anatolia, Turkey, is a part of the Alpine-Himalayan collisional belt where continental crust is relatively thin for a collisional belt. The region contains part of the Zagros suture zone, which formed during collision of the Arabian and Anatolian plates in the Miocene. It is underlain by a low-velocity zone associated with asthenospheric flow in the uppermost mantle.We constructed gravity models of the crust and upper-mantle structures to assess the driving mechanism of asthenospheric flow and the isostatic state of Eastern Anatolia. Our density models are based on terrestrial and satellite-derived gravity data, and they are constrained by receiver function and seismic tomography. The gravity models show significant lithospheric thickness variations across the Anatolian and Arabian plates. The lithospheric mantle in Eastern Anatolia is thinner (~62-74 km) than the Arabian plate (~84-95 km), indicating that part of the Anatolian mantle lithosphere might have been removed by delamination. The lithospheric removal process might have occurred following the detachment of the Arabian slab in the Miocene. Widespread Holocene volcanism and high heat flow in Eastern Anatolia can be considered as evidence of lithospheric delamination and slab break-off. The upward asthenospheric flow and subsequent asthenospheric underplating beneath Eastern Anatolia might have been induced by both delamination and slab break-off. These two processes may account for the rapid uplift of the Anatolian Plateau. There is a residual topography of ~1.7 km that cannot be explained by crustal roots. Based on our gravity models, we suggest that part of the eastern Anatolian Plateau is dynamically supported by asthenospheric flow in the upper mantle.

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Moho depth model for the Central Asian Orogenic Belt from satellite gravity gradients

2017

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The main purpose of this study is to construct a new 3‐D model of the Central Asian Orogenic Belt (CAOB) crust, which can be used as a starting point for future lithospheric studies. The CAOB is a Paleozoic accretionary orogen surrounded by the Siberian Craton to the north and the North China and Tarim Cratons to the south. This area is of great interest due to its enigmatic and still not completely understood geodynamic evolution. First, we estimate an initial crustal thickness by inversion of the vertical gravity component of the Gravity Field and Steady‐State Ocean Circulation Explorer (GOCE) and DTU10 models. Second, 3‐D forward modeling of the GOCE gravity gradients is performed, which determines the topography of the Moho, the geometry, and the density distribution of the deeper parts of the CAOB and its surroundings, taking into account the lateral and vertical density variations of the crust. The model is constrained by seismic refraction, reflection, and receiver function studies and geological studies. In addition, we discuss the isostatic implications of the differences between the seismic Moho and the resulting 3‐D gravity Moho, complemented by the analysis of the lithostatic load distribution at the upper mantle level. Finally, the correlation between the contrasting tectonic domains and the thickness of the crust reveals the inheritance of Paleozoic and Mesozoic geodynamics, particularly the magmatic provinces and the orocline which preserve their crustal features.

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Structure and State of Stress of the Chilean Subduction Zone from Terrestrial and Satellite-Derived Gravity and Gravity Gradient Data

Cited by 20 publications

References 55 publications

Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

Lithospheric structure and the isostatic state of Eastern Anatolia: Insight from gravity data modelling

Moho depth model for the Central Asian Orogenic Belt from satellite gravity gradients

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