共查询到20条相似文献，搜索用时 31 毫秒
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Hideo Aochi Marc Cushing Oona Scotti Catherine Berge-Thierry 《Geophysical Journal International》2006,165(2):436-446
The Middle Durance fault system, southeastern France, is a slow active fault that produced moderate-size historical seismic events and shows evidence of at least one M w ≳ 6.5 event in the last 29 000 yr. Based on dynamic rupture simulation, we propose earthquake scenarios that are constrained by knowledge of both the tectonic stress field and of the 3-D geometry of the Durance fault system. We simulate dynamic rupture interaction among several fault segmentations of different strikes, dips and rakes, using a 3-D boundary integral equation method. 50 combinations of reasonable stress field orientations, stress field amplitudes and hypocentre locations are tested. The probability of different rupture evolutions is then computed. Each segment ruptures mainly as a single event (44 per cent of the 50 simulations test in this paper). However, the probability that an event triggers simultaneously along three segments is high (26 per cent), leading to a potential rupture length of 45 km. Finally, 2 per cent of the simulations occur along four adjacent segments, producing the greatest total rupture length of 55 km. The simulation results show that the southernmost segment is most easily ruptured (40 per cent), because of its favourable orientation with respect to the tectonic stress and of its favourable location for interaction with the other segments. South-bound unilateral propagation is slightly preferable (41 per cent), compared to north-bound unilateral and bilateral propagation modes. Although, these rupture scenarios cannot be directly translated into probabilities of occurrence, they do provide a better insight as to which rupture scenarios are more likely, an important element to better estimate near-field strong ground motion and seismic hazard. 相似文献
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A. Douglas 《Geophysical Journal International》2007,169(2):502-505
Warren and Shearer describe a method of estimating the duration of P pulses radiated by earthquakes, on the assumption that the source is a unilateral fracture. The estimates are made in the frequency domain. The estimates obtained by Warren and Shearer for seven of the earthquakes are compared to durations estimated here in the time domain; the time-domain measurements being made on broad-band seismograms (∼0.1–4.0 Hz) derived by filtering from short-period recordings. Overall, the time-domain method indicates that the pulse duration of the earthquakes studied here range from 2.0 to 7.6 s, whereas the estimates from the results of Warren and Shearer range from 7.1 to 9.8 s. This suggests that the method of Warren and Shearer cannot resolve pulse lengths less than about 7 s. The suggestion is supported by the estimates of the duration of rupture—fault length/speed of rupture—implied by the results of Warren and Shearer. For, although the estimated fault-length ranges from 0.8 km to over 40 km most rupture durations are around 8 s. 相似文献
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Young-Fo Chang Chien-Chih Chen Chieh-Yu Liang 《Geophysical Journal International》2007,170(1):170-174
The 1999 September 20 Chi-Chi earthquake is the largest seismic event which occurred in the island during the twentieth century. Available seismic data relative to this earthquake are of high quality, and surface ruptures identified as features associated to the Chelungpu fault can be clearly observed at the surface and precisely mapped. We calculated the fractal dimension ( D ) and b value of Gutenberg–Richter law for 6-month aftershocks of the Chi-Chi earthquake for the fault area, and find that the surface ruptures exhibit self-similar geometry only within specific ruler intervals. The D values of the surface ruptures reflect the fault slip and geometry at depth. More importantly, the small-size aftershocks seem more likely to occur within high D value and high b value areas, whereas small D value and small b value areas have a high potential for medium- and large-size aftershocks. 相似文献
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Haruko Sekiguchi Kojiro Irikura Tomotaka Iwata 《Geophysical Journal International》2002,150(2):377-391
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Two distinct phases are commonly observed at the initial part of seismograms of large shallow earthquakes: low-frequency and low-amplitude waves following the onset of a P wave ( P 1 ) are interrupted by the arrival of the second impulsive phase P2 enriched with high-frequency components. This observation suggests that a large shallow earthquake involves two qualitatively different stages of rupture at its nucleation.
We propose a theoretical model that can naturally explain the above nucleation behaviour. The model is 2-D and the deformation is assumed to be anti-plane. A key clement in our model is the assumption of a zone in which numbers of pre-existing cracks are densely distributed; this cracked zone is a model for the fault zone. Dynamic crack growth nucleated in such a zone is intensely affected by the crack interactions, which exert two conflicting effects: one tends to accelerate the crack growth, and the other tends to decelerate it. The accelerating and decelerating effects are generally ascribable to coplanar and non-coplanar crack interactions, respectively. We rigorously treat the multiple interactions among the cracks, using the boundary integral equation method (BIEM), and assume the critical stress fracture criterion for the analysis of spontaneous crack propagation.
Our analysis shows that a dynamic rupture nucleated in the cracked zone begins to grow slowly due to the relative predominance of non-coplanar interactions. This process radiates the P1 phase. If the crack continues to grow, coalescence with adjacent coplanar cracks occurs after a short time. Then, coplanar interactions suddenly begin to prevail and crack growth is accelerated; the P2 phase is emitted in this process. It is interpreted that the two distinct phases appear in the process of the transition from non-coplanar to coplanar interaction predominance. 相似文献
We propose a theoretical model that can naturally explain the above nucleation behaviour. The model is 2-D and the deformation is assumed to be anti-plane. A key clement in our model is the assumption of a zone in which numbers of pre-existing cracks are densely distributed; this cracked zone is a model for the fault zone. Dynamic crack growth nucleated in such a zone is intensely affected by the crack interactions, which exert two conflicting effects: one tends to accelerate the crack growth, and the other tends to decelerate it. The accelerating and decelerating effects are generally ascribable to coplanar and non-coplanar crack interactions, respectively. We rigorously treat the multiple interactions among the cracks, using the boundary integral equation method (BIEM), and assume the critical stress fracture criterion for the analysis of spontaneous crack propagation.
Our analysis shows that a dynamic rupture nucleated in the cracked zone begins to grow slowly due to the relative predominance of non-coplanar interactions. This process radiates the P
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Simulation of the spontaneous growth of a dynamic crack without constraints on the crack tip path 总被引：2，自引：0，他引：2
The spontaneous growth of a dynamic in-plane shear crack is simulated using a newly developed method of analysis in which no a priori constraint is required for the crack tip path, unlike in other classical studies. We formulate the problem in terms of boundary integral equations; the hypersingularities of the integration kernels are removed by taking the finite parts. Our analysis shows that dynamic crack growth is spontaneously arrested soon after the bending of the crack tips, even in a uniformly stressed medium with homogeneously distributed fracture strengths. This shows that the dynamics of crack growth has a significant effect on forming the non-planar crack shape, and consequently plays an essential role in the arrest of earthquake rupturing. 相似文献
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Implications of a percolation model for earthquake 'nucleation' 总被引：2，自引：0，他引：2
Z. L.Wu 《Geophysical Journal International》1998,133(1):104-110
A percolation model is applied to the explanation of some of the qualitative and quantitative aspects associated with the recent observations of earthquake 'nucleation'. An additional assumption is introduced that nucleation starts at the critical point of percolation. The model explains the order of magnitude of the seismic moment release during the nucleation, the dependence of the seismic moment of the main shock on the duration of the nucleation process, and the observation that the fraction of the moment release during the nucleation has no systematic variation with the size of the main shock. The model also suggests that the source time function of the nucleation phase may be complex, and also that not all earthquakes are accompanied by a nucleation process, which is supported by observational results. By assuming that there exists a scale invariance associated with the criticality, a Widom scaling model is proposed to describe the electromagnetic emission during earthquake rupture. 相似文献
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