Heterogeneity and its Effect on Rotational Seismology (HERS)

• Applicant: Dr. Anjali Dhabu
• Subject Area: Geophysics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521891289

The present proposal aims to understand the effect of heterogeneities on the rotational ground motions due to earthquakes. With the improving instrumentation techniques, the rotational ground motions have evolved as a new observable in seismology. The combined analysis of translational and rotational motions due to an earthquake has improved the understanding of earthquake physics and wave propagation phenomena. In the absence of recorded data, the ground motions are often simulated to estimate damage due to an earthquake. The estimates of translational ground motions obtained from the analytical, empirical or numerical simulation techniques match well with the recorded data. However, whether the existing simulation models can capture the rotational ground motions is still a topic of concern. Recently, it is found that the strong, local heterogeneities near the receiver increase the amplitude of rotational ground motions. However, how and how much these heterogeneities can affect the characteristics of rotational ground motions remains an open question. In the present proposal, a parametric study will be carried out initially to identify the parameters that affect the heterogeneities and characterize how these parameters affect the simulated translational and rotational ground motions. After that, we will select a region of the European Union to develop a conventional and heterogeneous regional scale model. The conventional regional scale model refers to a model that incorporates the three-dimensional (3D) topography and lateral and longitudinal variation of material properties in the region of interest. The heterogeneous regional scale model includes strong local heterogeneities near the receiver in addition to the 3D topography and lateral and longitudinal variation of material properties. Finally, we will validate the simulations obtained from these models with the recorded data for two past earthquakes (i) Mw 6.8 that occurred on October 26, 2018, at 20.61°E, 37.33°N and 12km depth, (ii) Mw 5.9 that occurred on October 30, 2018, at 20.53°E, 37.44°N and 12km depth. Optimizing the heterogeneity parameters will be carried out so that the simulated rotational ground motions match well with the recorded data.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigators: Dr. Felix Bernauer; Professorin Dr. Céline Hadziioannou; Professor Dr. Heiner Igel
• Cooperation Partner: Professor Dr. Yann Capdeville