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Infrasound Signals and Their Implications From the 2024 M7.5 Noto Earthquake in Japan

Description: 

Earthquakes can generate infrasound, low-frequency (< 20 Hz) acoustic waves that propagate through the atmosphere as a result of surface ground motions near the epicenter. The study of earthquake-generated infrasound using remote sensor array data can provide constraints on the coupling mechanism between ground motion and the atmosphere, the level of strong ground motion around the source, as well as the propagation path effects through the atmosphere. The earthquake (M7.5, 1 January 2024) occurred on the west coast of Japan on the Noto Peninsula produced infrasound signals that were observed by at least 14 remote infrasound arrays to distances as great as 3489 km. This data set includes signals at six seismo-acoustic arrays operated cooperatively by Southern Methodist University and Korea Institute of Geoscience and Mineral Resources (KIGAM), three infrasound arrays operated by KIGAM, and five International Monitoring System infrasound stations in Japan, Russia, Mongolia, and US, designed to monitor the Comprehensive Nuclear-Test-Ban Treaty. In this study, we focus on the assessments of infrasound signal characteristics and constraints of propagation effects to reconstruct the earthquake source region that generated these waves. Infrasound signals from the main earthquake and aftershocks are identified based on the F-K analysis using array data. Multiple infrasound arrivals of coherent waves with long time durations (15 minutes to 1 hour) are linked to epicentral and diffracted infrasound sources with backazimuths changing in time, corresponding to the source location and the topography of the surrounding area. The atmospheric model predicts a two-directional stratospheric duct at the time of the earthquake associated with a sudden stratospheric warming event. Infrasound backprojections are produced using the backazimuths and arrival times at each array to image source locations. This event illustrates how infrasound observations accompanying earthquakes can be utilized to constrain strong ground motions near the source and the subsequent interactions of the coupled infrasound waves with the atmosphere.

Session: The 2024 Magnitude 7.5 Earthquake and the Associated Earthquake Swarm Beneath the Noto Peninsula, Central Japan - I

Type: Oral

Date: 5/3/2024

Presentation Time: 09:00 AM (local time)

Presenting Author: Junghyun

Student Presenter: No

Invited Presentation: 

Authors