Seismographic array observation in and around Iceland by use of ocean bottom seismographs and land seismometers.

利用海底地震仪和陆地地震仪对冰岛及其周边地区进行地震阵列观测。

基本信息

批准号：
02044003
负责人：
SHIMAMURA Hideki
金额：
$ 8.64万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Mid-Atlantic Ridge is the place where plate is being born. Iceland is situated immediately on the Ridge. There was no detailed study on crustal and upper mantle structure of any ridge. Also there was no detailed seismicity study around ridge. This study has revealed a very detailed seismicity in and around Iceland which made use of sensitive ocean bottom Seismograph (OBS) array.Also, crustal structure off north of Iceland was obtained in this study.Twenty OBS were transported from Japan to Iceland twice in 1990 and 1991. The OBS were deployed by an Icelandic Coast Guard Ship, for both years. In 1990, the OBS array was along Reykjanes Ridge, whose length is 150 km, and width is 40 km. The dense array observation was operated for one month continuously.The result shows that earthquake hypocenters are distributed only along the very crest area of the ridge, and no earthquake was observed outside of the ridge crest. We found some patches of concentrations of earthquakes along the ridge axis, which show a good correspondence to the past submarine volcanic activities. The depth distributions of observed earthquakes were nearly vertical, and the maximum depth was 12 km. Two microearthquake swarms were caught during the observation period, which shows a very concentrated epicenters with vertical chimney-like distribution of hypocenters.In 1991 similar OBS expeditions were made to the north off Iceland, where tectonics is more complicated than usual mid-oceanic ridges. 21 OBS as well as 15 land-based seismographs were deployed for the observation. Explosions were made for controlled source study of crust and upper mantle. The expedition was quite successful, and obtained data are now being processed.As a results of this study in 1990 and 1991, microseismicity of mid-oceanic ridge in Icelandic region has been clearly revealed, which is for the first time in any ridge. Also, a detailed crustal structure of the ridge has been obtained.

中大西洋山脊是盘子诞生的地方。冰岛立即位于山脊上。没有关于任何山脊的地壳和上地幔结构的详细研究。另外，Ridge周围没有详细的地震性研究。这项研究揭示了冰岛及其周围的地震性非常详细，它利用了敏感的海洋底部地震仪（obs）阵列。此外，冰岛北部的地壳结构在这项研究中也获得了。二十个obs在1990年和1991年两次从日本运输到冰岛。冰岛海岸警卫队两年都将其部署到冰岛海岸警卫队的两年中。 1990年，OBS阵列沿着雷克雅内斯山脊的长度为150 km，宽度为40公里。稠密的阵列观察连续进行了一个月。结果表明，地震降压体仅沿着山脊的极rest区分布，并且在山脊波峰外没有观察到地震。我们发现沿着山脊轴的一些浓度的地震浓度，这些地震表现出与过去的海底火山活动的良好对应关系。观察到的地震的深度分布几乎是垂直的，最大深度为12 km。在观察期间，捕获了两只微鞭子群，这表明一个非常集中的震中具有垂直的烟囱样的低中心物。 21个OBS和15个陆基地震仪进行了观察。爆炸是用于控制地壳和上地幔的受控来源研究。这次探险非常成功，现在正在处理获得的数据。作为这项研究的结果，1990年和1991年，冰岛地区中大洋山脊的微观震动已清楚地揭示出来，这是任何山脊首次在任何山脊中。同样，还获得了脊的详细地壳结构。