[论文解读] Use of high resolution satellite images for tracking of changes in the lineament structure, caused by earthquakes

A. A. Arellano-Baeza, R. V. García+1 more|ArXiv.org|Jun 13, 2007

Earthquake Detection and Analysis参考文献 40被引用 3

一句话总结

本研究利用ASTER/TERRA高分辨率多光谱卫星图像，检测强震（Mw ≥ 5.2）前地壳线性构造系统的变化。通过应用LESSA软件进行线性构造提取与条带密度分析，发现重大地震前约1个月，线性构造数量及重新取向显著增加，尤其在汇聚型板块边界区域，表明其可能与地壳应力积累及扩容过程相关，具有潜在前兆信号特征。

ABSTRACT

Over the last decades strong efforts have been made to apply new spaceborn technologies to the study and possible forecast of strong earthquakes. In this study we use ASTER/TERRA multispectral satellite images for detection and analysis of changes in the system of lineaments previous to a strong earthquake. A lineament is a straight or a somewhat curved feature in an image, which it is possible to detect by a special processing of images based on directional filtering and or Hough transform. "The Lineament Extraction and Stripes Statistic Analysis" (LESSA) software package, developed by Zlatopolsy (1992, 1997). We assume that the lineaments allow to detect, at least partially, the presence ruptures in the Earths crust, and therefore enable one to follow the changes in the system of faults and fractures associated with strong earthquakes. We analysed 6 earthquakes occurred in the Pacific coast of the South America and XXX with the Richter scale magnitude >4.5. They were located in the regions with small seasonal variations and limited vegetation to facilitate the tracking of features associated with the seismic activity only. It was found that the number and orientation of lineaments changed significantly about one month before an earthquake approximately, and a few months later the system returns to its initial state. This effect increases with the earthquake magnitude, and it is much more easily detectable in case of convergent plate boundaries (for example, Nasca and South American plates). The results obtained open a possibility to develop a methodology able to evaluate the seismic risk in the regions with similar geological conditions.

研究动机与目标

• 探究通过高分辨率卫星图像可见的地质线性构造系统的变化是否可作为强震的前兆。
• 评估利用遥感数据在地震事件前监测地壳应力积累的可行性。
• 评估线性构造变化在不同构造环境中的稳定性与可检测性，特别是汇聚型边界区域。
• 基于卫星影像中观察到的动态线性构造演化，开发一种地震风险评估方法。
• 将观测到的线性构造变化与未受地震活动影响的对照区域进行对比验证。

提出的方法

• 获取地震前、中、后时期的ASTER/TERRA多光谱卫星图像（分辨率15–30 m）。
• 应用LESSA软件包（Zlatopolsky, 1992, 1997）通过方向滤波与霍夫变换技术进行线性构造提取。
• 通过与圆形掩模卷积计算条带密度场，随后进行残差分析以检测重新取向模式。
• 生成玫瑰图与拉东变换，量化线性构造取向与密度随时间的变化。
• 对比地震影响区域与距震中数百公里外参考区域的线性构造动态变化。
• 采用图像阈值化处理（本研究设定为120）以优化线性构造检测并减少噪声。

实验结果

研究问题

• RQ1 通过卫星图像检测到的线性构造系统的变化是否可作为强震的可靠前兆？
• RQ2 在重大地震发生前的一个月内，线性构造的数量与取向如何演变？
• RQ3 线性构造变化在多大程度上与地震震级及构造环境相关，特别是在汇聚型板块边界？
• RQ4 与背景噪声或非地震区域相比，观测到的线性构造变化是否具有统计显著性？
• RQ5 条带密度场残差是否能为破裂前的地壳扩容提供额外证据？

主要发现

• 在强震（Mw ≥ 5.2）发生前约一个月，观察到线性构造数量显著增加，且在汇聚型板块边界附近区域尤为明显。
• 条带密度场残差与拉东变换分析显示的线性构造重新取向，表明其与地壳应力积累及扩容过程存在动态关联。
• 地震发生约一个月后，线性构造系统逐渐恢复至初始构型，表明该前兆信号具有瞬态特征。
• 在距震中数百公里外的对照区域未检测到显著的线性构造变化，证实了所观测现象的局地性。
• 地震震级与线性构造变化的强度呈正相关，震级越大，前兆信号越明显且分布越广泛。
• 利用ASTER图像（分辨率15–30 m）可检测到地壳尺度的构造变化，尽管地表形变通常仅在厘米量级。