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Seismic Moment Tensors Evaluation of Earthquakes in Central Zagros (Iran)

Description: 

Due to the influence of crustal structure on wave propagation, seismic waves contain substantial information about the Earth's crust, and their analysis contributes significantly to a better understanding of the Earth’s interior. Calculating the moment tensor based on seismic data is one of the physical methods for classifying and physically interpreting seismic sources. An earthquake moment tensor is a complete representation of interval forces on a point source which represents its fault geometry and size using moment tensor components and scalar moment, respectively. Specifically, each tensor component represents the dynamic effect in a particular direction, which can be calculated by decomposing the moment tensor. By doing so, we can analyze the earthquake source mechanism.
This study used the Global Centroid Moment Tensor (GCMT) catalog to calculate seismic moment tensors of events with M≥5 in Central Zagros (CZ), Iran, based on seismic data (e.g., strike, dip, and rake angles). We decomposed each diagonalized tensor into two parts: Isotropic (ISO) and Deviatoric (M’). To evaluate the contribution of each component to the seismic source, we further decomposed M’ into a best Double Couple (DC) and Compensated Linear Vector Dipole (CLVD) components. Moreover, owing to the convergence of the Arabian and Eurasian plates that formed Zagros Mountain in the western part of Iran, we expected to find only DC faulting in this region. However, we found more than 50% of misfit between M’ and a pure DC for some events, indicating that the CLVD faulting type was dominant. We found a good agreement between the locations of these events and the geology structures, including active anticlines, active salt domes, fault links, and fault tips which are the local effect of dominant CLVD in this area.
Keywords: Moment Tensor, Central Zagros, Deviatoric Moment Tensor, Double Couple (DC), Compensated Linear Vector Dipole (CLVD).

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Zohreh Abbasi Hafshejani

Student Presenter: Yes

Invited Presentation: 

Authors