2015年4月15日内蒙古阿拉善左旗MS5.8地震前后CH4和CO变化

基于卫星高光谱数据讨论鄂尔多斯西缘CH₄和CO气体背景场特征和2015年4月15日内蒙古阿拉善左旗M_S5.8地震前后气体异常变化。 结果表明, CH₄和CO气体总量在时间上均存在显著的季节变化, 空间分布上受构造地质背景、 地形地貌影响, 高值区位于银川、 吉兰泰、 河套断陷盆地。 2015年4月15日内蒙古阿拉善左旗M_S5.8地震当月, CH₄异常沿鄂尔多斯西缘断裂带呈线性展布, 地震前1周左右, 震中两侧油气田出现CH₄异常, 异常幅度达到6倍标准偏差, 与地震引起附近油气田CH₄逸出增加有关; CO异常空间分布与CH₄基本一致, 时间上滞后CH₄异常1周左右, 持续2周左右后消失。 CH₄和CO关系密切, CO异常部分源自CH₄氧化。

Anomalies on the Changes of CH4 and CO related to the15 April 2015 Alashan Zuoqi MS5.8 Earthquakein the Inner Mongolia

The anomalies of TotCH4 and TotCO associated with the 15 April 2015 Alashan Zuoqi M_S5.8 earthquake were discussed based on the satellite hyper-spectrum data. The background in monthly and anomaly-index of TotCH4 and TotCO were calculated from AIRS standard 3 level product data in recent years (2003—2012). The results showed that the TotCH4 and TotCO backgrounds in the study area presented obviously seasonal variations in temporally. Spatially, the distributions of TotCH₄ and TotCO were affected by the tectonic geological background and topographic landform. The high values of TotCH₄ and TotCO were located in Yinchuan, Jilantai and Hetao fault-sinking basins. TotCH4 anomaly appeared linearly along western edge of Ordos fault in April, while TotCH₄ appeared in oil-gas-bearing basins on both sides of the epicenter about 1 week before the major shock with the maximum anomaly index reached 6. TotCO anomaly appeared when and after the main shock, and lasted for two weeks. And the spatial distribution of TotCO anomaly was consistent with the CH₄. There was a close relationship between CH₄ and CO. The CO anomaly was partly derived from the CH₄ oxidation.