尼泊尔8.1级地震卫星热红外异常解析

摘要

Aiming at the thermal infrared anomaly in the epicentral area of Nepal Ms 8.1 earthquake,this paper collected the infrared remote sensing brightness temperature data of China Geostationary Meteorological satellite FY-2C/E,and analyzed the data by using power spectrum transform method.The results showed that the thermal anomaly had obvious temporal and spatial characteristics,and the anomaly range was in irregular zonal distribution,which gradually expand over time and tend to peak when the earthquake occurred.The epicenter was always located in the edge of anomaly area,and the anomaly rapidly shrank after the earthquake until completely disappeared.The change process of thermal anomaly was divided into three stages,namely preliminary display,rapid development and gradual decay,whose duration was more than 45 days,characteristic period was 16 days,and the magnitude of relative variation was more than 12 times.Through the comparative study,we found that the evolution of thermal infrared characteristics in this earthquake was similar to Wenchuan earthquake,mainly reflected in the evolution process,morphology and the relationship of seismic moment and epicenter location with the anomaly area.These two earthquake cases only had different characteristic period and peak value,and this difference may be related to the regional stress,climatic factors and special geological environment.The cognizance in this paper had certain enlightenment function to determine the relationship between the thermal anomalies and the three elements of earthquake,and had a great significance to the thermal infrared monitoring and earthquake prediction.%针对2015年4月25日尼泊尔8.1级地震前后在震中区附近出现的大范围热红外异常,以中国静止卫星FY-2C/E亮温资料为数据源,采用功率谱相对变化法进行数据处理和资料分析,结果表明:震前热异常具有显著的时空特征,异常范围呈不规则带状分布,且随时间推移逐渐扩大,至震时异常面积趋于峰值,震中始终位于异常区域的边缘部位,震后异常快速收缩减弱,直至完全消失.该次热异常变化表现为初步显现、加速发展至逐步衰减的过程,持续时间在45天以上,特征周期为16天,相对变化幅度达12倍多.通过相似震例对比研究发现,该次地震与汶川大地震的热红外时空演化特征存在一定共性,主要体现在热异常的演化过程、异常形态、发震时刻及震中位置与异常区域的关系上,仅特征周期和特征幅值有所不同,应与各区域应力变化、气候因素及特殊的地质环境相关.这些认识对热异常与地震三要素的关系判定有一定启示作用,对地震热红外监测预报工作具有重要意义.