scholarly journals Corrigendum to “Geo- and seismo-tectonics of Eastern Himalaya: Exploring earthquake source zones from foredeep to Tibetan hinterland”, Physics and Chemistry of the Earth, Issue 123 (2021) JPCE 103013”

2021 ◽  
pp. 103071
Author(s):  
Sujit Dasgupta ◽  
Basab Mukhopadhyay ◽  
Manoj Mukhopadhyay ◽  
Prabhas Pande
Keyword(s):  
Earthquake Source ◽  
Eastern Himalaya ◽  
The Earth ◽  
Source Zones

Geo- and seismo- tectonics of Eastern Himalaya: Exploring earthquake source zones from foredeep to Tibetan hinterland

2021 ◽  
pp. 103013
Author(s):  
Sujit Dasgupta ◽  
Basab Mukhopadhyay ◽  
Manoj Mukhopadhyay ◽  
Prabhas Pande
Keyword(s):  
Earthquake Source ◽  
Eastern Himalaya ◽  
Source Zones

Nonuniformity of crack-growth resistance and breakdown zone near the propagating tip of a shear crack in brittle rock: A model for earthquake nucleation to dynamic rupture

1990 ◽  
Vol 68 (9) ◽  
pp. 1071-1083 ◽  
Author(s):  
Mitiyasu Ohnaka
Keyword(s):  
Crack Growth ◽  
Constitutive Relation ◽  
High Frequency ◽  
Crack Growth Resistance ◽  
Earthquake Source ◽  
Source Process ◽  
Zone Model ◽  
The Earth ◽  
Shear Rupture ◽  
Propagating Shear

This paper reviews our recent studies on (i) slip failure nucleation, which leads to the mechanical instability that gives rise to a dynamically propagating shear rupture, (ii) constitutive behavior during the local breakdown process near the propagating tip of the slipping zone, and (iii) the physical modeling of the earthquake-source process based on the constitutive relation inferred from laboratory experiments. Laboratory studies were done using a simulated fault in rock in the brittle regime under a mode II crack-growth condition, to gain a deeper understanding of the earthquake-source process, which is considered to be dynamically propagating shear rupture in the earth. A stable but accelerating phase of nucleation locally precedes an unstable dynamically propagating rupture even in the brittle regime. The appearance of a sizable zone of such nucleation is related to a nonuniform distribution of the crack-growth resistance on the fault. The local shear strength degrades to a residual friction stress level with ongoing slip near the propagating tip of the slipping zone. This slip-dependent constitutive relation shows that there is a breakdown zone near the propagating tip over which shear stress, slip displacement, slip velocity, and slip acceleration are highly nonuniform. This nonuniformity is responsible for generating high-frequency elastic radiation. A model of the breakdown zone, which incorporates the laboratory-based constitutive relation, does not give rise to unrealistic singularities of slip acceleration and stresses at and near the dynamically propagating tip of the slipping zone. The breakdown zone model enables one to give a common interpretation to both small-scale slip failure in the laboratory and large-scale shear failure as earthquake faulting in the earth, and it can explain the earthquake-source strong motion characterized by the high-frequency content.

scholarly journals A project of creating atlas aftershocks of strong earthquakes

2019 ◽  
pp. 79-84
Author(s):  
A. V. Guglielmi ◽  
A. D. Zavyalov ◽  
O. D. Zotov
Keyword(s):  
Inverse Problem ◽  
Strong Earthquake ◽  
Main Shock ◽  
Earthquake Source ◽  
Problem Solution ◽  
Strong Earthquakes ◽  
Omori Law ◽  
The Earth ◽  
Interesting Possibility ◽  
Source Physics

The Omori Law, which describes the repeated underground shocks after a strong earthquake, is written in the form of a nonlinear differential equation. An idea of the focal deactivation coefficient after the main shock is introduced. Two advantages of the new wording of the Omori Law are given. Firstly, there is an interesting possibility to naturally take into account exogenous and endogenous triggers affecting the earthquake source. Endogenous triggers in the form of round-the-world seismic echo and free oscillations of the Earth, excited by the main shock, are especially noted. The second advantage is that the differential aftershock equation makes it possible to put the reverse problem of the earthquake source physics. The essence of the inverse problem is to determine the deactivation coefficient from the data on the observed aftershock frequency. Examples of inverse problem solution are given. The project of creation of the Atlas of aftershocks on the basis of the solution of the inverse problem of the source, cooling down after a strong earthquake is offered.

Deep structure and tomographic imaging of strong earthquake source zones

2006 ◽  
Vol 42 (10) ◽  
pp. 850-863 ◽  
Author(s):  
S. S. Arefiev ◽  
E. A. Rogozhin ◽  
Zh. Ya. Aptekman ◽  
V. V. Bykova ◽  
C. Dorbath
Keyword(s):  
Strong Earthquake ◽  
Deep Structure ◽  
Tomographic Imaging ◽  
Earthquake Source ◽  
Source Zones

GENERATION OF SYNTHETIC ACCELEROGRAMS USING ENGINEERING EARTHQUAKE SOURCE MODEL

2004 ◽  
Vol 04 (04) ◽  
pp. 497-514 ◽  
Author(s):  
SHAILESH KR. AGRAWAL
Keyword(s):  
Elastic Medium ◽  
Mean Squared Error ◽  
Strong Motion ◽  
Source Model ◽  
Earthquake Source ◽  
Acceleration Time ◽  
The Earth ◽  
Acceleration Time Histories ◽  
Earthquake Source Model ◽  
Time Histories

The strong motion records available during an earthquake can be treated as the response of the earth as a structural system to unknown forces acting at unknown locations. Thus, if the part of the earth participating in ground motion is modeled as a known finite elastic medium, one can model the source location and forces generated during the earthquake as an inverse problem. Based on this analogy, a simple model for the earthquake source is proposed, by assuming the source to be a sequence of impulses acting at locations yet to be found. These impulses and their locations are found using the normal mode expansion along with a minimization of mean squared error. The medium is assumed to be finite, elastic, homogeneous, layered and horizontal with specified boundary conditions. Detailed results are obtained for the Uttarkashi earthquake of 20th October 1991, in India. The impulse locations are shown to be closely associated with the underlying fault mechanism. The proposed model is then used to simulate the acceleration time histories at a few recording stations. The earthquake source expressed in terms of a sequence of impulses acting at different locations is applied to a 2D finite elastic medium. The acceleration time histories found from this model agree well with with the accelerations recorded for the earthquake.

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