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High-Resolution Three-Month Aftershock Catalog using Nodal Stations of the 2023 Kahramanmaraş Earthquake Sequence in Southeastern Türkiye

Description: 

The Kahramanmaraş earthquake doublet on February 2023 in Southeastern Türkiye started with a Mw 7.8 earthquake at Sakçagöz-Narlı Fault rupturing the East Anatolian Fault (EAF) for more than 300 km. Nine hours later, a Mw 7.5 earthquake occurred near Ekinözü; this earthquake ruptured nearly 100 km along the adjacent Çardak fault. Both mainshocks have triggered a great number of aftershocks along the faults and surrounding areas in the complex Maras triple junction. To better map the ongoing aftershock sequence, we deployed approximately 200 5-Hz SmartSolo nodal stations and 16 broadband/strong motion seismic stations across the rupture zone focusing on major clusters and potential areas under threat, for more than three months starting in May 2023. These SmartSolo nodal stations are set with a sampling rate of 500 Hz to record higher quality waveforms from smaller aftershocks, as compared with a 100 Hz sampling rate from typical broadband stations. In this work, we start with the earthquake catalog with more than 15,000 events in the same period of nodal deployment from the Turkey Disaster and Management Authority (AFAD) catalog. The P and S arrivals are picked, using the PSIR method, in the nodal stations and used as templates for subsequent matched-filter detection (MFD). We also apply a deep-learning phase picker called EQTransformer and its association method to the continuous nodal records to help identify more events that were not listed in the AFAD catalog, which adds more template events for the MFD. Our preliminary results show that MFD can detect micro-earthquakes hidden in the noise with very small magnitudes. Waveform-based relocation methods are then applied to all detected events to build a more complete catalog. With a higher resolution catalog, fault and seismic structures, especially splay faults along the EAF and the adjacent faults can be identified and imaged for an improved understanding of potential seismic hazards in this region. Additionally, we expect to better decipher the physical mechanism of aftershocks and processes that drive the evolution of seismicity in Southeastern Türkiye.

Session: Illuminating Complex, Multiplet Earthquake Sequences at Kahramanmaras (Turkiye), Herat (Afghanistan), and Beyond [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Phuc

Student Presenter: Yes

Invited Presentation: 

Authors