Fault-plane Identification by a Geometrical Method – Application to Moderate Earthquake Mw 5.1 Kerman, Iran

Hejrani, Babak; Hatami, Mohammad; Mousavi, Seyed Morteza

doi:10.3997/2214-4609.201401311

Cited by 2 publications

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“…There are a number of ways in which a choice can be made between conjugate fault plane solutions, for example, by using directivity calculations (French et al, ; Warren & Shearer, ), or the H‐C method (Hejrani et al, ). However, in most cases, this level of sophistication is not necessary.…”

Section: Four Principles For Structural Analysis Of Seismotectonic Datamentioning

confidence: 99%

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Structural Geology and the Seismotectonics of the 2004 Great Sumatran Earthquake

et al. 2018

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The paper sets out a method for structural analysis of seismotectonic data using centroid moment tensors and associated hypocenters from the Global Centroid Moment Tensor project, here illustrated for aftershocks from the 2004 great Sumatran earthquake. We show that the Sumatran segments of the megathrust were subject to compression in a direction near to orthogonal with the margin trend, consistent with the effect of relative movement of the adjacent tectonic plates. In contrast, the crust above the Andaman Sea segments was subject to margin‐orthogonal extension, consistent with motion toward the gravitational potential well accumulated due to prior lateral (westward) rollback of the subducting edge of the northward moving Indian plate. Since this potential well is largely defined by topography, this episode of margin‐orthogonal extension is at least in part “gravity driven.” It did not last long. Within 15 months, an earthquake cluster across an Andaman Sea spreading segment showed a return to kinematics driven by relative plate motion. The transition can be explained if fluid activity temporarily reduced basal friction (or effective stress) but then led to healing so that the megathrust once again began to develop friction‐locked segments. The influence of slab rollback is in developing a gravitational potential well facing the megathrust, hence drawing the overriding crust toward it in the immediate postrupture phase while the megathrust is in a weakened state. Plate tectonics dominates during interseismic gaps, once the megathrust heals, and regains frictional resistance.

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Section: Four Principles For Structural Analysis Of Seismotectonic Datamentioning

confidence: 99%

“…Tectonics 10.1002/2017TC004708 (Hejrani et al, 2010). However, in most cases, this level of sophistication is not necessary.…”

Section: Geology Allows Choice Between Conjugate Fault Plane Solutionsmentioning

confidence: 99%

Structural Geology and the Seismotectonics of the 2004 Great Sumatran Earthquake

et al. 2018

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“…1D,1E,and 1F). It was also possible to resolve ambiguity for strike-slip fault solutions, by computing hypocenters and centroids for individual earthquakes using the Hypocenter-Centroid (H-C) method (Zahradník et al, 2005(Zahradník et al, , 2008Hejrani et al, 2010). This H-C method allowed classification of fault plane pole and slip line orientation clusters based on the fault plane solution that allows the alignment of the earthquake hypocenter and centroid in the same plane.…”

Section: Introductionmentioning

confidence: 99%

Lineaments and earthquake ruptures on the East Japan megathrust

et al. 2018

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In this paper we describe the earthquake geology of East Japan, based on a seismotectonic analysis of foreshocks and aftershocks for the 2011 Tohoku-oki Great Earthquake. The earthquake geology is defined by three compressional buttresses that are separated by channels dominated by extensional earthquakes. In the 2011 earthquake sequence, most activity occurred in the Tohoku-oki extensional channel. This is bounded by seismotectonic lineaments that run subparallel to the slip direction of thrust-fault earthquakes in the adjacent compressional buttresses, and to the slip direction of landward-dipping normal-fault aftershocks in the subducting Pacific plate. The northern bounding seismotectonic lineament of the Tohoku-oki extensional channel runs WNW-ESE ~15 km north of the Miyagi Volcanic Lineament. The southern bounding seismotectonic lineament runs ~20 km to the south of the Fukushima Volcanic Lineament. These lineaments may reflect faults that splay from deeper structures beneath the volcanic lineaments. In any case, the seismotectonic lineaments appear to reflect zones of weakness, and as is the case in any load-bearing architecture, precursor movements on such focusing structures may herald the onset of catastrophic failure. We discovered that two-thirds of all major earthquakes with moment magnitude M w ≥6.9 in the past 40 years in East Japan began within 15 km of the seaward prolongation of a volcanic lineament, and that motion across the northern seismotectonic lineament reversed its sense in the days prior to the 2011 Great Earthquake, suggesting the onset of yield. We infer that continuous geodetic monitoring across the East Japan lineaments might thus provide useful signals for future hazard assessment.

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Fault-plane Identification by a Geometrical Method – Application to Moderate Earthquake Mw 5.1 Kerman, Iran

Cited by 2 publications

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Structural Geology and the Seismotectonics of the 2004 Great Sumatran Earthquake

Structural Geology and the Seismotectonics of the 2004 Great Sumatran Earthquake

Lineaments and earthquake ruptures on the East Japan megathrust

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