Characterization of Source, Path and Site Effects on Ground Motions From the 2023 Kahramanmaraş, Türkiye, Earthquake Sequence
Description:
We seek to understand the physical processes that generated the strong ground motions observed during the 2023 Kahramanmaraş, Türkiye, earthquake sequence, reasons why recorded motions may differ from existing ground motion models (GMMs), and factors controlling the observed variability. The devastating 2023 Türkiye earthquake sequence, which included the M7.7 Pazarcik mainshock and the M7.5 Elbistan aftershock, occurred along the Eastern Anatolian Fault Zone. Because these destructive earthquakes represent a nearly unprecedented set of near-source ground-motion records, understanding their genesis could improve GMMs and hazard estimates in Türkiye and worldwide. We perform an ensemble GMM residual analysis, examining ground motions from the 2023 sequence as well as other previous regional earthquakes, using a total of 63 M5+ events, including the 2010 M6.1 Elazig and 2020 M6.7 events, recorded on 1116 stations. Using many smaller earthquakes allows for robust sampling of source, site, and path effects, including consideration of more complex spatially varying and azimuth-dependent effects that we might expect to be present on a nationwide scale. We consider ground-motion residuals for spectral acceleration between 0.05s and 10s, as well as peak ground motions relative to a reference GMM of Boore et al. (2014; BSSA14) and partition them into components representing repeatable source, path, and site effects to understand the relative contribution of each. The BSSA14 GMM includes an anelastic attenuation term that is specific to Türkiye, and we observe that overall, the ground motions for the two largest events are well modeled at all distances and periods. Directivity is evident in the ground motions for the largest events, consistent with the complex multi-fault rupture. For the moderate aftershocks, the data within ~50km are well modeled by BSSA14 but show overprediction at distance, implying anelastic attenuation for the smaller events on the Eastern Anatolian Fault Zone is stronger than along the Northern Anatolian Fault Zone, from which data was used to constrain the model.
Session: February 2023 Mw 7.8 Earthquake Sequence in Turkey [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Annemarie S. Baltay
Student Presenter: No
Invited Presentation:
Authors
Grace Parker Corresponding Author gparker@usgs.gov U.S. Geological Survey |
Annemarie Baltay Presenting Author abaltay@usgs.gov U.S. Geological Survey |
Eric Thompson emthompson@usgs.gov U.S. Geological Survey |
Mehmet Çelebi celebi@usgs.gov U.S. Geological Survey |
Brad Aagaard baagaard@usgs.gov U.S. Geological Survey |
Ayşegül Askan aaskan@metu.edu.tr Middle East Technical University |
Abdullah Altindal abdullah.altindal@metu.edu.tr Middle Eastern Technical University |
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Characterization of Source, Path and Site Effects on Ground Motions From the 2023 Kahramanmaraş, Türkiye, Earthquake Sequence
Category
February 2023 Mw 7.8 Earthquake Sequence in Turkey