中国渤海地区海底地震观测的初步研究

A Preliminary Study on Sea-bottom Seismograph Observation in Bohai Sea Area, China

摘要:

本文是在日本造船振兴财团的经费赞助下在中国渤海地区发展海底地震观测的初步技术报告。
本报告主要包括以下内容:
(1)渤海及其邻近地区的地震活动性与地震危险性估计;
(2)渤海地区海底地震观测的条件;
(3)渤海地区海底地震观测仪器与技术的某些初步研究结果;
(4)浅海情况下海底地震观测噪声的模拟实验研究结果。
文中研究了该地区的历史与现代地震活动性、长期地震危险性以及发生在华北与日本的大地震之间的关系。还讨论了渤海强震和海啸对渤海及其邻近海域航海的影响问题。在这些研究结果的基础上对在渤海地区开展海底地震观测的必要性进行了解释。
本文探讨了在渤海地区进行海底地震观测的某些仪器和技术问题。天津市地震局曾在渤海地区石油平台的油井中作过初步地震观测试验。日本气象厅气象研究所发展的海底地震观测中有关降低噪声与信号传输等方面的新技术与经验可用于渤海地区的海底地震观测。在这些研究的基础上,提出了一个在中国渤海地区发展渤海地震观测的初步设想。指出渤海海底地震观测试验应从观测和研究渤海海底海洋噪声谱开始。
为了研究浅海情况下海底地震观测的噪声,本文完成了一项新的模拟试验工作。分别对海面源及海内源产生的噪声进行了实验研究。文中给出了一些重要实验结果。
本文所得的初步结果,对发展渤海及邻近地区海底地震观测有一定的参考价值。

Abstract:

The present paper is a preliminary technical report of the development of ocean-bottom seismograph observation in the Bohai Sea area of China, conducted under financial support from Japan Foundation for Shipbuilding Advancement.
This report mainly includes the following contents:
(1) The seismicity and seismic risk assessment of the Bohai Sea area and its vicinity.
(2) Conditions for sea-bottom seismograph observation in the Bohai Sea area.
(3) Some results of preliminary study on instruments and techniques for ocean-bottom seismograph observation in the Bohai Sea area.
(4) The results of experimental modelling researches on the noises of ocean-bottom seismograph observation in the case of shallow sea.
The historical and present seismicity, the long-term seismic risk, and the relation between large earthquakes which occurred in North China and Japan have been studied. The problems on influences of a strong earthquake and tsunami upon the Bohai Sea navigation routes and near populated areas were discussed. Based on the result the necessity of sea-bottom seismograph observation in the Bohai Sea area was explained.
The conditions in the Bohai Sea area, introduced in this paper, include the sea-bottom geomorphology, strong waves and meteorological conditions, and the sea navigation and Sea work condition in this sea area.
Some problems on the instruments and techniques for sea-bottom seismograph observation in the Bohai Sea area were studied and discussed. The preliminary seismograph observation test at the platform of an oil well in the Bohai Sea area was made by the Seismological Bureau of Tianjin, Some new techniques, and successes in noise reduction and signal transmission etc. of sea-bottom seismograph observation advanced by the Meteorological Research Institute of Japan Meteorological Agency (JMA) may be applied to the sea-bottom seismograph observation in the Bohai Sea area. On the basis of these results, a preliminary project to develop the sea-bottom seismograph observation in the Bohai Sea area of China was proposed.
To study the noises of sea-bottom seismograph observation in the case of shallow sea, a new experimental modelling research has been completed. The noises caused by sea surface source and sea interior source were studied separately. Some important experimental results have been presented.
The preliminary results, obtained in this paper, may be useful to develop the sea-bottom seismograph observation in the Bohai Sea area and its vicinity.