Deep-low Frequency Earthquakes on the Downward Extension of the Seismogenic Fault of the 2000 Western Tottori Earthquake
| Autor: | OHMI, Shiro, HIROSE, Issei, MORI, James J. |
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| Jazyk: | japonština |
| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | 京都大学防災研究所年報. B. 47:691-696 |
| ISSN: | 0386-412X |
| Popis: | 平成12年(2000年)鳥取県西部地震の震源域では，本震前から深部低周波地震(DLF)が発生しており，本震後に活動が活発化した。これらのDLF地震は，震源断層の深部延長上に位置しており，断層の非地震性下部延長上で発生している可能性がある。地震波速度構造や非抵抗構造などからは，この領域には水等の流体が存在すると予想され，これが断層下部延長部の非地震性すべりや，上部地殻への応力蓄積に影響を与えている可能性がある。DLF地震はそれらの流体の活動の指標のひとつとして重要であろう。 Deep low-frequency (DLF) earthquakes have been discussed in association with fluid (magma)activity around volcanoes. In this paper, however, we will show another example of DLF activity beneathactive faults in the western Tottori region where a Mw6.7 earthquake occurred on October 2000. DLFearthquakes had been observed prior to the mainshock and the activity was increased after the mainshock.They are distributed around 30 km depth and seem to be located at the downward extension of theseismogenic fault. Seismic tomography analysis and the resistivity structure both indicate the fluid activityin the focal region of the DLF events. One of the DLF earthquakes exhibits the single-force type sourcemechanism, which indicates the transport of fluid such as water or magma. Therefore, these DLFearthquakes are probably the direct evidence of the fluid activity of the downward extension of theseismogenic fault. |
| Databáze: | OpenAIRE |
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