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地震

地震 ›› 2004, Vol. 24 ›› Issue (4): 73-79.

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强震中期阶段区域性形变异常的共性特征及其机制以青藏块体东北部为例

王双绪, 张希, 张四新, 张晓亮   

  1. 中国地震局第二监测中心, 陕西 西安 710054
  • 出版日期:2004-10-31 发布日期:2021-11-29
  • 作者简介:王双绪(1959-), 男, 陕西歧山人, 研究员, 主要从事地壳形变与地震预报及地球动力学等研究。
  • 基金资助:
    “十五”中国地震局重点科研项目(100501-05-04); 地震科学联合基金项目(104011)

Common characteristics and mechanism of regional deform- ation anomaly in medium-term phase of strong earthquakes Taking the northeastern Qinghai-Xizang block as example

WANG Shuang-xu, ZHANG Xi, ZHANG Si-xin, ZNANG Xiao-liang   

  1. The Second Monitoring and Application Center, CEA, Xi'an 710054, China
  • Online:2004-10-31 Published:2021-11-29

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摘要： 强震前中期阶段(1～3年或稍长)区域性形变异常往往表现出3个方面的共性特征: ① 区域垂直运动变形呈现与构造有关的异常隆起区、 垂直差异变形高梯度带(有的还呈“四象限”)分布特征; ② 水平运动变形呈现与活动地块及断裂构造有关的、 以剪切变形为主的高应变集中区(带)特征; ③ 区域性垂直形变异常区与水平形变的高应变分布区共生的特征。 分析这些异常共性特征的形成机制, 初步认为: 它们是在基本统一的大区域构造应力场控制下, 不同层次块体系统运动及其边界带变形的非平稳、 非协调性, 在活动地块边界地带和地块内部次级断裂构造部位产生变形差异而导致应力-应变积累、 孕育强震到一定阶段的结果。 在此基础上, 分析探讨了基于区域性形变异常共性特征、 结合地质构造活动背景进行强震中期预测的意义。

关键词: 强震中期阶段, 区域性形变异常, 共性特征, 形成机制

Abstract: The regional deformation anomaly of medium-term phase (1~3 years or more) before strong earthquake occurrence usually shows three aspects of common characteristics: ① For regional vertical deformation, it shows distribution features of anomalous uplift area and concentration belt-high gradient belt of vertical differential deformation (some of them reflect distribution of four quadrants) related to tectonics; ② For horizontal movement, it shows features of centralized high strain area (or zone) of domination shear deformation related to active blocks and faults; ③ It shows common features of regional vertical deformation anomaly area and high strain distribution area of horizontal deformation. Having analyzed preliminarily formation mechanism of these common characteristics of anomaly, it concludes that: these are results, controlled by basically united tectonic stress field of large-range, caused by stress-strain accumulation and certain phase strong earthquakes, according to deformation difference brought about in tectonic position along the boundary zone and within second-order faults of active blocks resulted from unstable and inharmonious features for movement of block system at different levels and deformation of boundary. Based on the above, the meaning of medium-term prediction of strong earthquakes is discussed in the light of common features of regional deformation anomaly and combined with background of geological tectonic activities.

Key words: Medium-term phase of strong earthquakes, Regional deformation anomaly, Common characteristics, Formation mechanism

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