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High-resolution Imaging of Fault Damage Zones Based on Multiple Ultra-dense Arrays in the Aftershock Zone of the 2023 Kahramanmaras Earthquake Sequence in Southern Türkiye

Description: 

The 2023 Kahramanmaras earthquake sequence included two events of magnitude 7.5 and 7.8 only nine hours apart causing significant damage and loss of life in southern Turkey and northern Syria. To capture the ongoing aftershock sequence and image fault zone structures in greater detail, we deployed an array of up to 200 5-Hz Smartsolo nodal stations and 16 broadband/strong motion stations across the rupture zone for ~100 days beginning in May 2023 which we termed the “Eastern Anatolian Seismic Temporary” (EAST) array. We also deployed an ultra-dense fault zone profile across the Pazarcık segment of the East Anatolian Fault (EAF) and the Sakçagöz-Narlı Fault (SNF) where the M7.8 mainshock initiated. In Fall 2024, we deployed four additional dense fault zone profiles across and along the Pazarcık segment of the EAF where the M7.8 mainshock likely ruptured at a supershear speed. In this study, we present preliminary results from the analysis of fault zone waves recorded by these ultra-dense fault zone profiles. Specifically, we selected local earthquakes from a new high-resolution earthquake catalog built using our nodal recordings. Next, we use both visual inspection and automatic methods to detect fault zone trapped waves (FZTWs) that are recorded by stations close to the surface rupture zones. We examine the moveout of the FZTWs associated with both hypocentral depth and source-receiver geometry to better understand the depth extent and asymmetric properties of the fault damage zones. We also attempt to detect fault zone head waves (FZHWs) that refract along the bi-material fault interface to better quantify the velocity contrasts across multiple fault segments. Our preliminary results suggest the presence of an asymmetric damage zone further to the east across the Pazarcık segment of the EAF, which is consistent with the preferred damage zone along a bi-material rupture zone. Future work will examine other fault-zone profiles and combine waveform modeling of fault zone waves and body-wave tomography to better understand the relationship between fault zone properties and earthquake rupture behaviors.

Session: Innovative Applications of Seismic Nodal Technology for Hazard Mitigation and Earth System Monitoring - I

Type: Oral

Date: 4/15/2025

Presentation Time: 02:45 PM (local time)

Presenting Author: Michael

Student Presenter: Yes

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