利用Terra和Aqua卫星地表温度探索汶川地震同震热响应

如何从卫星热红外遥感影像中提取出可靠的、能够验证的、与构造活动有关的热信息,是利用热红外信息研究构造现今活动亟待完善的问题之一.从信息提取的角度看,地震前后所对应的物理变化最为强烈,同震热响应可能是利用热信息探索现今构造活动潜在的突破点.本文以MODIS/Terra和MODIS/Aqua两颗卫星的地表温度为基础,探索汶川地震同震热响应.首先,去除了由地形等静态因素和太阳年周期组成的稳定背景;其次,去除大气环流的影响,获得由本地因素产生的原地温度场.最后,在原地温度场中,发现了汶川地震的同震温度响应.经过检验,上述温度响应的空间展布形态与发震断层的活动方式产生的力学效应吻合.从应力变化与温度响应的关系看,本文相当于借助热信息获得了汶川地震同震拉张或卸载区的空间展布情况.

Exploring co-seismic thermal response of Wenchuan earthquake by using Land Surface Temperatures of Terra and Aqua Satellites

There are many problems which should be solved when thermal infrared information is applied to exploring the current tectonic activities. One of these problems is to obtain the reliable, testable information related to tectonic activity through the satellite thermal infrared image. From the viewpoint of signal processing, thermal information changes largely before and after the strong earthquake. Specially, the co-seismic thermal response is the breakthrough point to investigate current tectonic activity. In this paper, the MODIS/Terra and MODIS/Aqua land surface temperature products are applied to detecting the co-seismic response of Wenchuan earthquake. The effects of non-tectonic factors on land surface temperature are carefully considered. Firstly, the stable background of land surface temperature is extracted from land surface temperature. Then, influences of atmosphere circulation and mankind activity are gotten rid of, with consideration of spatial frequency difference between tectonic and non-tectonic activities. At last, the co-seismic temperature-dropping response of Wenchuan earthquake is found in the left temperature field which stems from the in-situ factors. Furthermore, the spatial distribution of co-seismic response is in accordance with the mechanical mode related to the fault activity. According to the relationship between temperature response and stress-strain, this regional lowering temperature is equivalent to the co-seismic unloading or tension.