Seismic Hazard Analysis in Nicaragua – a Summary

Larsson, Tara; Mattson, C.

doi:10.1016/b978-0-444-98955-0.50037-9

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…Seaward migration of the volcanic arc seems to have also occurred in the Pliocene [ Weinberg , 1992]. Seismic data show a Wadati‐Benioff zone down to 200 km only, consistent with recent subduction of a new slab [ Burbach et al , 1984; Larson and Mattson , 1987; Protti et al , 1994; Engdahl et al , 1998; Rogers et al , 2002]. From geomorphic analysis and tomographic images, Rogers et al [2002] estimated that the slab broke off 9–6.7 Ma ago (in late Miocene) and the modern slab started subducting 3.8 Ma ago (in Pliocene) consistent with the observed length of the slab.…”

Section: Discussionmentioning

confidence: 91%

“… Ranero et al [2000] suggested that the offshore inner forearc is currently tectonically active. However, the inner forearc does not exhibit any motion and seems to be seismically quiescent [ Larsson and Mattson , 1987; Weinberg , 1992] (Figure 1c). In contrast, the outer forearc, 0–80 km from the trench, shows distributed seismicity and normal faulting associated with uplift [ Larsson and Mattson , 1987; Ranero et al , 2000].…”

Section: Introductionmentioning

confidence: 99%

“…In the sedimentary basin, layers are as defined by Ranero et al [2000]. The white dots are the 1975–1982 hypocenters from Larsson and Mattson [1987]. (d) Close‐up of basin sedimentary layers and middle Miocene deformation phase from Ranero et al [2000].…”

Section: Introductionmentioning

confidence: 99%

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Past forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat?

Cailleau

Oncken

2008

Geochem Geophys Geosyst

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[1] Deformation at the boundary between the Cocos and Caribbean plates in Nicaragua is currently focused in the volcanic arc in the form of arc-parallel shearing. In the middle Miocene, however, there was widespread subsidence with local uplift in the outer-forearc and inner-forearc broad uplift. To understand this complex deformation, we use numerical modeling to investigate the effect of inhomogeneous friction at the megathrust fault on strain localization in the upper plate. A good fit is obtained when (1) the interface between the slab and upper plate is not situated at the current Wadati-Benioff zone but rather is moved 50 km landward to where subduction may have been active in the early Tertiary and (2) there is high stress accumulation between 15 and 25 km depths and low stress accumulation updip and downdip of the thrust interface. The results are consistent with a high-velocity block being the remnant of an oceanic plateau that subducted in the Eocene and was later incorporated into the upper plate. We suggest that this geometry persisted into the middle Miocene, before the slab broke off and the thrust interface jumped seaward.

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Section: Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Past forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat?

Cailleau

Oncken

2008

Geochem Geophys Geosyst

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“…Depth distribution of hypocentres of earthquakes in the subduction zone west of Nicaragua and below the Nicaraguan Depression(Larsson & Mattson 1987). The distribution is based on 2564 records from the period between 1975 and 1982.…”

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confidence: 99%

Results of magnetotelluric and gravimetric measurements in western Nicaragua, Central America

Elming

Rasmussen

1997

Geophysical Journal International

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Magnetotelluric and gravity data have been collected within a ca. 170 km long traverse running from the Pacific coast of Nicaragua in the west to the Nicaraguan Highland in the east. This part of Nicaragua is characterized by sedimentary rocks of the Pacific Coastal Plain, separated from the Tertiary volcanic rocks of the Highland by the NW-SE-trending Nicaraguan Depression. 2-D interpretation of the magnetotelluric (MT) data, collected at 13 stations, indicates four regions of high electrical conductivity in addition to the conductive coastal region. Two of these are associated with conducting sediments and pyroclastics in the upper part of the crust. Two other conductive structures have been defined at depth around 20 km and the one best defined is located below the depression. From the distribution of seismic events, volcanic activity in the depression and the similarity in geophysical characteristics with areas such as the Rio Grande Rift, this conductor is interpreted as a melt layer or a complex of magma chambers. Models of the upper lithosphere, constrained by the MT model, vertical electrical sounding (VES) data, seismic data and densities, have been tested using gravity data. A model that passes this test shows a gradual thickening of the crust eastwards from the Pacific coast. An anomaly centred over the depression is interpreted to have its origin in a thinning of the crust. In this model the melt layer is situated on top of the bulge of the lower lithosphere. A change in the composition of the crust, from the Pacific Coastal Plain to the Highland, is indicated from the change in character of the MT response and from the density distribution in the gravity model. This may support the hypothesis that the Pacific region is an accreted terrane. MT and gravity data indicate a depth to a resistive and high-density basement in the depression of ca. 2 km. On the basis of this, the vertical setting in the depression is estimated to be of the order of 2.5 km.

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“…A seismic hazard map based on probabilities of horizontal peak ground accelerations would be the base for a better building code. For the Nicaraguan seismic area, some work in hazard analysis (Shah et al, 1975;Zapata, 1984;Larsson and Mattson, 1987;Johansson, 1988) and in earthquake engineering (Toivanen and Wagenius, 1989) has already been done.…”

Section: Introduction and Central American Tectonicsmentioning

confidence: 99%

Probabilistic macroseismic hazard assessment for Nicaragua (preliminary results)

Espinosa

1996

Nat Hazards

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A probabilistic macroseismic hazard assessment has been done for Nicaragua. For this, the most complete catalogue for Central America, compiled by NORSAR in Norway has been used. In this catalogue, empirical intensity attenuation relations were found. Using these empirical relations, magnitudes were changed to epicentral intensities expected in sites where no intensities had been reported. The calculated intensities from a polygon surrounding Nicaragua were used to assess the macroseismic hazard in the region. For the whole polygon, the cumulative intensity frequency was calculated resulting in a b-value of 0.60 for an intensity interval of V-IX. The time completeness was also studied indicating that, for strong events causing higher intensities (lo > VII), the catalogue is complete for events that have been recorded since 1840. The whole polygon was cut into independent seismotectonic regions where the statistical procedure (intensity frequency and time completeness) was done.

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Seismic Hazard Analysis in Nicaragua – a Summary

Cited by 5 publications

References 2 publications

Past forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat?

Past forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat?

Results of magnetotelluric and gravimetric measurements in western Nicaragua, Central America

Probabilistic macroseismic hazard assessment for Nicaragua (preliminary results)

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