Attenuation structure in northeastern Japan inferred from characteristic observations of a high-frequency wave for intraslab earthquakes
Abstract
We investigate a high-frequency later phase (HFL) which is observed for intraslab earthquakes occurred at intermediate depths, especially those depths of greater than 100 km, in northeastern Japan. The HFL has often been detected in high-frequency bands (>4 Hz), with abnormal arrival delays compared to that of the direct S wave. Here, we assume the HFL is a single scattered wave and estimate its propagation path by applying the source-scanning algorithm [Kao and Shan, 2004]. The scattering source determined in this study distributes in the forearc region, at depths of about 30-80 km, indicating that the HFL pass through the forearc region. These observations of the HFL also implies that significant differences in S-wave attenuation property between the forearc and backarc region in northeastern Japan; the strong S-wave attenuation in the backarc mantle wedge controls on high-frequency waves of intraslab earthquakes, in addition to the presences of scatterers in the forearc region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41J0270S
- Keywords:
-
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8158 Plate motions: present and recent;
- TECTONOPHYSICS;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY