Low-frequency Events away from Volcanoes in the Japan Islands: ―その分布と発生原因―
Low-frequency Events away from Volcanoes in the Japan Islands: ―その分布と発生原因―
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日本列岛火山以外的低频事件：-分布及发生原因-
DOI：
10.4294/zisin1948.57.1_11
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
A. Katsumata
中科院分区：
文献类型：
--
作者：
Noriko Kamaya;A. Katsumata
近年来，日本改进后的地震网络在莫霍罗维奇不连续面附近发现了低频事件，但远离火山。这些地震可分为两类：低频地震（LFE）和低频震颤（LFT）。LFE的源区分布在日本各地的孤立位置，而LFT的源区分布在日本西部的一个带内。虽然LFE直接低于火山以前已经认识到，LFE远离火山代表新的观察。这些LFE被发现特别是在日本东北部的火山前缘的弧后，并在日本西部的LFT带以北。LFE和LFT持续时间长，表明流体参与了它们的生成。本研究考虑触发LFE和LFT的源过程，使用水饱和的大洋玄武岩和橄榄岩的高压和高温实验结果作为模型。这些物质是下降板块内部和周围的代表。在日本西部的LFT的情况下，该模型提供了，作为一个可能的触发器，水的脱水释放的玄武岩中的菲律宾海板块的下降和形成单斜辉石。另一方面，在整个日本的LFE的情况下，不仅来自板片的水，而且在板片和地幔楔中产生的岩浆和来自岩浆的高温流体也是可能的触发器。由于LFE具有明显的P波起始点，因此LFE的产生可能涉及某种断裂。LFE和LFT有望成为地震预报的有用指标，但大地震或震群与LFE和LFT发生的关系尚待确定。
In recent years, improved seismic networks in Japan have detected low-frequency events near the Mohorovicic discontinuity, but away from volcanoes. These can be classified as two types: lowfrequency earthquakes (LFE) and low-frequency tremors (LFT). Source regions for LFE are distributed in isolated locations throughout Japan, while those for LFT are distributed within a belt in western Japan. Although LFE immediately below volcanoes have been previously recognized, LFE away from volcanoes represent new observations. These LFE are found specifically both in the back-arc of the volcanic front in northeastern Japan, and to the north of the LFT belt in western Japan. LFE and LFT have long durations, suggesting the involvement of fluids in their generation. This study considers the source processes that trigger LFE and LFT, using the results of high pressure and temperature experiments on water-saturated oceanic basalt and peridotite as a model. Such materials are representative of those in and around the descending slab. In the case of LFT in western Japan, the model provides, as a possible trigger, the water released by the dehydration of chlorite and forming clinopyroxene in the basalt of the descending Philippine Sea Plate. On the other hand, in the case of LFE throughout Japan, not only water from the slab but also magma generated in the slab and mantle wedge and high temperature fluid derived from the magma are possible triggers. Because LFE have clear P-wave onsets, some sort of fracture is likely to be involved in the generation of LFE. LFE and LFT are expected to be indicators useful in earthquake prediction, but the relationships between large earthquakes or earthquake swarms and the occurrence of LFE and LFT are yet to be determined.
影响因子：
2.9
作者：
HASEGAWA, A;YAMAMOTO, A
通讯作者：
YAMAMOTO, A
影响因子：
56.9
作者：
Obara, K
通讯作者：
Obara, K