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    May 19

    汶川地震是印度板块惹的祸

    汶川地震成因机理
    2008-05-18 信息来源:中国地质调查局

    5月15日下午,中国地质调查局召开汶川地震及其诱发的次生地质灾害情况分析会,航遥中心、环境监测院、地科院、地质所、地质力学所等单位的专家根据各自调查监测和评价研究的结果对灾情进行“会诊”。初步形成如下认识:

    汶川地震是印度板块惹的祸

    印度板块向亚洲板块俯冲,造成青藏高原快速隆升。高原物质向东缓慢流动,在高原东缘沿龙门山构造带向东挤压,遇到四川盆地之下刚性地块的顽强阻挡,造成构造应力能量的长期积累,最终在龙门山北川-映秀地区突然释放。

    汶川地震是逆冲、右旋、挤压型断层地震

    第一,发震构造是龙门山构造带中央断裂带,在挤压应力作用下,由南西向北东逆冲运动。第二,这次地震属于单向破裂地震,由南西向北东迁移,致使余震向北东方向扩张。第三,挤压型逆冲断层地震在主震之后,应力传播和释放过程比较缓慢,可能导致余震强度较大,持续时间较长。

    汶川地震是浅源地震

    汶川地震不属于深板块边界的效应,发生在地壳脆-韧性转换带,震源深度为10-20千米,因此破坏性巨大。

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