[S09P-03] Using dense triad sub-arrays to detect and locate very low-frequency earthquakes in Japan
Very low frequency earthquakes (VLFEs) share a high resemblance with ordinary (fast) earthquakes in long-period seismic radiation, whilst their lack of high-frequency radiation is one of the characteristics of slow earthquakes. Thus, VLFEs may occur under unique fault conditions that may reveal physical mechanisms of slow and fast earthquakes. However, the detection and location of VLFEs have been challenging attributed to their lack of clear body wave phases, and the associated seismic signals are similar to those from coupled systems of the solid Earth, the ocean, and the atmosphere. To identify VLFEs from continuous seismic waveforms, previous studies often rely on template-matching techniques, which can be limited by the available templates.
Here, we apply a modified surface wave detector that is based on the Automated Event Location Using a Mesh of Arrays (AELUMA) method to explore unconventional seismic sources near Japan. The AELUMA method can effectively detect and locate seismic sources using local coherence across a triad sub-array. The method does not require phase-picking, prior knowledge of source types, or an accurate velocity model to calculate the travel times. Therefore, our method is ideal for identifying unconventional seismic sources that are commonly missed in standard catalogs. The dense seismic networks in Japan provide an excellent opportunity to use this method to investigate unconventional seismic sources.
We will present our recent development of the AELUMA method using the F-net broadband data and the Hi-net high-sensitivity accelerometer (tiltmeter) data. We will demonstrate our approach by detecting example VLFEs at the Hyuga-nada region that were previously overlooked through other detection means. Further, we will model these VLFE source mechanisms, including the seismic moment and the duration. We aim to gain new insight into the related fault conditions.
Here, we apply a modified surface wave detector that is based on the Automated Event Location Using a Mesh of Arrays (AELUMA) method to explore unconventional seismic sources near Japan. The AELUMA method can effectively detect and locate seismic sources using local coherence across a triad sub-array. The method does not require phase-picking, prior knowledge of source types, or an accurate velocity model to calculate the travel times. Therefore, our method is ideal for identifying unconventional seismic sources that are commonly missed in standard catalogs. The dense seismic networks in Japan provide an excellent opportunity to use this method to investigate unconventional seismic sources.
We will present our recent development of the AELUMA method using the F-net broadband data and the Hi-net high-sensitivity accelerometer (tiltmeter) data. We will demonstrate our approach by detecting example VLFEs at the Hyuga-nada region that were previously overlooked through other detection means. Further, we will model these VLFE source mechanisms, including the seismic moment and the duration. We aim to gain new insight into the related fault conditions.