Intraplate seismicity in Brazil

Assumpção, Marcelo; Ferreira, Joaquim Mendes; Barros, Lucas Vieira; Bezerra, Hilario; França, George Sand; Barbosa, José Roberto; Menezes, E. A.; Ribotta, L. C.; Pirchiner, Marlon; Nascimento, A. Do; Dourado, João Carlos

doi:10.1017/cbo9781139628921.004

Cited by 48 publications

(51 citation statements)

References 57 publications

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“…cit.). The Assumpção et al (2011Assumpção et al ( , 2014 Assumpção et al (2011). Topographic profile A-A' made with DEM data from Smith & Sandwell (1997).…”

Section: Discussionmentioning

confidence: 99%

“…A diffuse belt of seismicity occurs near or beyond the Cretaceous hinge line (Fig. 16) where the continental crust becomes highly extended (Assumpção, 1998;Assumpção et al, 2011Assumpção et al, , 2014; see maps by Assumpção et al, 1997, Zalán & Oliveira, 2005Zalán et al, 2011). Several of its earthquakes were characterized by compressional focal-plane mechanisms and had well-located hypocenters that indicated middle or upper crustal depths (Assumpção et al, 2011).…”

Section: The Model Abroadmentioning

confidence: 99%

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Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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To a first order, patterns of Fennoscandia's seismicity reflect the benchmark domain boundaries of its Mesozoic rifted margin. Three distinct belts of earthquakes strike sub-parallel to the generalized line of breakup. The outermost seismic belt (SB1) marks the Taper Break (TB), or the zone of flexural coupling/decoupling between the distal (seaward) and proximal/necking (landward) domains. A coastal belt (SB2) follows the Innermost Limit of Extension, defined as the onset of 39 km-thick crystalline continental crust. An interior belt (SB3) follows the Hinterland Break in Slope, or the landward limit of the Scandinavian rifted margin. Between each belt, large portions of the necking, proximal, and hinterland domains are seismically quiescent. Evaluation of the 'Cumulative Seismic Moment' (CSM w ) per unit area indicates that the release of seismic energy is asymmetric. Although some of Fennoscandia's largest seismic events occur in the dominantly Proterozoic to Archean lithosphere of the eastern craton, 80% of Fennoscandian CSM w maps to the domain boundaries of the western rifted margin. CSM w energy tends to be highest at the TB and decreases system atically towards the continental interior.As proposed by many previous studies, a first-order spatial correlation between Scandinavia's offshore earthquake belt and voluminous, geo logically rapid, sedimentary loading during the Neogene period is evident. However, the presence of thinned, faulted crystalline basement is also a very important factor behind Scandinavia's offshore seismicity. Where the Neogene deposits are at their thickest the underlying crust is dominantly oceanic; CSM w is lower per unit area there than where lesser Plio-Pleistocene loading impacts continental crust that was fully prepared by Mesozoic necking and hyperextension. CSM w data suggest that the 'strength' of the TB and the continental margin's distal domain is significantly less than that of relatively young (ca. 54 Ma) oceanic lithosphere. Our data imply that ridge push does not contribute significantly to Fennoscandia's seismicity. Rather, we find that thin-plate bending stresses stemming from offshore depositional loading conspire with unbuttressed Gravitational Potential Energy (GPE), onshore erosion, and post-glacial isostatic rebound to generate Fennoscandia's earthquakes.We present a conceptual seismological model for Fennoscadia that is consistent with modern hypotheses of extended margin evolution, including post-breakup reactivation by footwall uplift in regions adjacent to sharp crustal taper. Illustrated by simple concepts of elastic thin-plate theory, the model honors our conclusion that Fennoscandian seismicity is principally the product of locally derived stress fields and that far field stress from the oceanic domain is unlikely to penetrate deeply into a hyperextended continental margin. It predicts the locations of the observed seismic belts and seismic gaps with the mathematics of thin-plate bending. It describes how the outer seismic belt will remain localized in the...

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“…cit.). The Assumpção et al (2011Assumpção et al ( , 2014 Assumpção et al (2011). Topographic profile A-A' made with DEM data from Smith & Sandwell (1997).…”

Section: Discussionmentioning

confidence: 99%

Section: The Model Abroadmentioning

confidence: 99%

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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“…Located in the stable continental interior of the South American Plate, Brazil is characterized by low levels of seismicity (magnitude 5 occur only once every 4 yr) and shallow crustal depths (mostly <10 km; Berrocal et al 1984;Assumpção et al 2014). The largest recorded event in this stable region was the 1955 m b = 6.2 Serra do Tombador earthquake (Barros et al 2009), which is at least one magnitude unit less than the largest recorded magnitude in other stable continental interiors in the world (e.g.…”

Section: The 2012 Montes Claros Earthquake and Its Context In The Bramentioning

confidence: 99%

“…• S, seismicity in Brazil tends to concentrate offshore in the continental shelf rather than onshore in the continental interior (Assumpção 1998b;Assumpção et al 2014). At this latitude, inland Brazil is not exempt from important seismic activity, such as the 2007 m b = 4.9 Caraíbas-Itacarambi earthquake, which caused the first death from an earthquake in Brazil (Chimpliganond et al 2010).…”

Section: The 2012 Montes Claros Earthquake and Its Context In The Bramentioning

confidence: 99%

The 2012–2013 Montes Claros earthquake series in the São Francisco Craton, Brazil: new evidence for non-uniform intraplate stresses in mid-plate South America

Agurto‐Detzel

Assumpção

Ciardelli

et al. 2014

Geophysical Journal International

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an m b = 4 earthquake shook the town of Montes Claros, Brazil in the middle of the São Francisco Craton. Because of the scarce seismicity in the area, an event like this could provide valuable information to characterize the governing seismotectonics and stress field for the region. Here, we present the results of more than 1 yr of local seismic monitoring after the main shock. We found that the seismicity originated at approximately 1-km depth in an NNW-oriented blind reverse fault, dipping to the E. The magnitude of the main shock was 4m b , with aftershocks reaching up to 3.6m b . Focal mechanisms from first motion polarities and waveform moment tensor inversions indicate a reverse faulting in agreement with the orientation of the aftershock locations. In addition, we derived a new 1-D local velocity model using a simultaneous inversion of hypocentres and velocity layers. The results indicate P-wave velocities of 4.5 km s −1 for the upper layer of carbonate rocks and 5.23 and 5.69 km s −1 for the lower fractured and compact crystalline basement layers, respectively. Higher Vp/Vs ratios were obtained for the upper two layers compared to the lowermost layer, possibly indicating presence of rock fracturing and percolated water. The calculated stress drop for the main event is 0.33 MPa, which is a relatively low value for an intraplate earthquake but still within the observed range. The inversion of the main shock focal mechanism and previously published focal mechanisms suggests a compressional stress regime in the central part of the São Francisco Craton, which is different from the strike-slip regime in the southern part, although both have an EW-oriented σ 1. On the other hand, focal mechanisms of events located to the west of the craton indicate an NW-SE oriented σ 1 for central Brazil. This variability highlights the importance of local sources of stresses (e.g. flexural stresses) in mid-plate South America, unlike other mid-plate areas of the world, such as central and east North America, where a more uniform stress field is observed.

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“…These ear thquakes are along with disturbance and nature equilibrium disturbin and there is direct relation among induced earthquake and human activity.therefore, we should expect the center of these false earthquakes be on human activity eras (Assumpcao, et al, 2002 Occurring induced earthquake in dam reservoir is due to parameters like tension eras condition, stone hydromechanical character uncer reservoir, eras geology and also dimensions and fluctuations of water level in dam reservoir (Berberian, et al,. 1999).…”

Section: Introductionmentioning

confidence: 99%

Analytic Study of Inductive Earthquake Occurring Due to Tabriz Veniar Dam Reservoir Supplying With Water

Javdani¹,

Zade²

2015

Curr. World Environ

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Tabriz Vaniar dam by reservoir volume about 360 milion cubic meters, and 50 meter height of river bed, is an earth dam with clay core. This dam is along with north Tabriz fault of active one by historical background of earthquake. Therefore, it requires studying possibility of inductive earthquake occurring on this dam.we have considered noram tensions ¡ ¡ and cross one ¡ ¡ in limit of 40-45 kilometer from dam by considering reservoir loads in the center of earthquake for1×1network kilometer and on north fault of tabriz in order to study potential of inductive earthquake on Vaniar Tabriz dam. in this study, We have used of 19 december 2007 earthquake affairs in which shows stumbling direction in right direction and is concordant with north Tabriz fault. We have used of speedometer apparatus in order to determine earthquake affairs andrecognizing fault face and analyzed result by mathematic models. According to the amount of analysis, We concluded increasing earthquake deep decreases reservoir effects. The most effect of reservoir is on 1-4kilometers deep and also the amount of fault satability S r (t) is less than zero on north. Tabriz fault in which indicated the influence of Vaniar dam reservoir on Tabriz fault that push forward earthquake.

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Intraplate seismicity in Brazil

Cited by 48 publications

References 57 publications

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

The 2012–2013 Montes Claros earthquake series in the São Francisco Craton, Brazil: new evidence for non-uniform intraplate stresses in mid-plate South America

Analytic Study of Inductive Earthquake Occurring Due to Tabriz Veniar Dam Reservoir Supplying With Water

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