直下に断層を有する堆積平野の地震応答に関する研究

断层沉积平原地震响应研究

• 批准号: 08248209
• 负责人: 年縄 巧
• 金额: $ 0.83万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-08248209/
• 关键词: 地下地震; 堆積平野; 地震被害; 地震動増幅; 地震観測; 数値シミュレーション

甲府盆地では,1854年安政東海地震及び1923年関東地震において平野の一地域で震度6の被害を記録した.甲府盆地とこれら2つの地震の震源距離はどちらも60km程度であったが被害の集中した地域は異なっていた.すなわち,1854年安政東海地震の際には盆地南西部に被害が集中し,1923年関東地震の際には盆地南東部で被害が集中するという,地震波の到来方向に依存する被害パターンが生じた.本研究では,1923年関東地震の被害分布の成因を説明するために盆地南東部から北部の地盤をモデル化し,数値解析を行った.地盤モデルを作成するために,まず盆地内で常時微動測定を行い,卓越周期を推定し,弾性波探査の結果を参考として地表面のP波・S波速度,密度,厚さを決定した.その結果,地盤モデルはS波速度は220m/s程度,表層の地盤厚さは深いところで60m程度となった.この地盤モデルを用いて入射波の周期や入射角をパラメターとして数値解析を行い,1923年の関東地震の際に被害が大きかった地域は,傾斜地盤の影響によって地震動の振幅が増幅されることがわかった.数値解析と平行して,甲府盆地の4地点において地震観測を開始した.これら4地点の地震記録と科学技術庁防災科学研究所の観測記録を用いれば,盆地内の地震波の伝播特性,増幅特性を明らかにすることが期待される.また,盆地内の構造をさらに詳しく調べるために来年度は長周期微動のアレー観測を行う予定であり,得られた地盤構造を基に甲府盆地を3次元的にモデル化し,1923年関東地震の被害分布だけでなく1854年の安政東海地震の被害分布の成因についても検討したいと考えている.

Kofu Basin earthquake, 1854 Yasumasa Tokai earthquake and 1923 Kanto earthquake, earthquake intensity 6 recorded. The focal distance of earthquakes in Jiafu Basin is 60km, and the concentration of victims is different. In 1854, the victims were concentrated in the south-western part of the basin during the Anzheng East China Sea earthquake, and in 1923, the victims were concentrated in the south-eastern part of the basin during the Kanto earthquake, depending on the direction of arrival of seismic waves. This study is aimed at explaining the origin of the damage distribution of the Kanto earthquake in 1923, and analyzing the numerical value of the damage distribution in the southern and eastern parts of the basin. The results of seismic wave exploration can be used as a reference to determine the velocity, density and thickness of P wave and S wave on the surface of the earth. As a result, the velocity of the S wave in the surface layer is about 220m/s, and the thickness of the surface layer is about 60m. The period and angle of incidence of the incident wave were analyzed by numerical value analysis. The Kanto earthquake in 1923 was damaged by large area, and the amplitude of the ground vibration increased due to the influence of inclined ground. The seismic survey began at 4 locations in the Kofu Basin. The seismic records of the four sites and the seismic records of the Institute of Science and Technology for Disaster Prevention are used in the study. The propagation characteristics and amplitude characteristics of seismic waves in the basin are expected to be clear. The structure of the basin was studied in detail, and the long-period micro-motion of the basin was measured in the coming years. It was found that the structure of the basin was based on the three-dimensional micro-motion of the Kofu basin. The distribution of victims of the Kanto earthquake in 1923 and the cause of the distribution of victims of the Anzheng earthquake in the East China Sea in 1854 were studied.

项目成果

T.TOSHINAWA: "Interpretation of microtremor records." The 1995 Hyogoken-Nanbu Earthquake-Inuestigation into damage to civil Engineering structures,JSCE. 27-34 (1996)

T.TOSHINAWA：“微震记录的解释。”

T.TOSHONAWA,M.MATSUOKA and Y.YAMAZAKI: "Ground-motion characteristics in Sartiago,Chile,obtained by microtremor observations" Proc.of the 11th World Conference on Earthquake.Engineering. No.01764. (1996)

T.TOSHONAWA、M.MATSUOKA 和 Y.YAMAZAKI：“通过微震观测获得的智利萨尔蒂亚戈的地面运动特征”第 11 届世界地震工程学会议论文集。