2010年新西兰M7.1地震前的长波辐射变化特征

以2001—2011年美国NOAA长波辐射数据为背景数据,利用涡度背景场法研究2010年9月3日新西兰南岛M7.1级地震前后卫星长波辐射数据变化特征。结果表明,地震当月在震中西南侧出现显著的长波辐射异常变化,这种变化在全年各月及2001—2011年11年历年同月变化中都是最为显著的,认为其是本次地震的1次映震表现。用同样方法对区内2001—2011年11年间发生6次7.0级以上地震的长波辐射数据进行分析,结果在3次陆地地震发震前都检测到了长波辐射异常变化,而海域地震前则未发现这种现象。检索前人的相关研究结果,发现仅有2次海域地震(2004年12月26日印度尼西亚苏门答腊西北海域8.7级地震和2010年1月12日海地7.0级地震)前有长波辐射异常变化的报道,而根据全球云量分布资料显示,这2个地震所发生的区域是全球洋面云量分布最少的2个区域,而新西兰地震发生的区域位于全球洋面云量分布最多的区域。因此,认为由于水汽和云层对地表红外辐射的强吸收作用,长波辐射捕捉陆地地震红外辐射异常变化更加灵敏,对陆地地震的映震效能要强于海洋地震。

Variation of Outgoing Longwave Radiation around the Time of New Zealand Earthquake M7. 1, 2010

The variation characteristics of outgoing longwave radiation (OLR) around the time of New Zealand Earthquake M7.1 September 3, 2010 have been analyzed based on eleven years (2001 2011) background data using vorticity background method. The results indicated that the maximum increase of OLR was found in the month of the main shock and the position of the variation was distributed in the south west of the epicenter. This variation was the most remarkable during the annual monthly data and monthly data in September from 2001 to 2011, which can be considered as the reflection to this earthquake. Six earthquakes with the magnitude greater than 7.0 in this region from 2001 to 2011 have been analyzed using the same method. The results have shown that OLR anomalies have been detected in three continental earthquakes and without anomalies in three coastal earthquakes. For comparison, the published reports related to OLR seismic studies have been retrieved. Only two coastal earthquakes (M8.7 off the west coast of northern Sumatra earthquake of December 2004 and M7.0 Haiti earthquake of January 2010) have been detected with OLR anomalies. According to the global distribution of cloud amount, the two regions of Sumatra and Haiti earthquakes are covered by the minimum cloud amount in global ocean. But the region of Zealand earthquake is covered by the maximum cloud amount in global ocean. So, it is believed that OLR is more sensitive to continental earthquakes than coastal earthquakes in reflecting seismic thermal infrared anomalies because water vapor and cloud can absorb much of surface outgoing infrared radiation.