基于MODIS数据的2023年甘肃积石山Ms6.2地震热红外异常检测研究

Thermal Infrared Anomaly Detection of the 2023 Gansu Jishishan Ms6.2 Earthquake Based on MODIS Data

摘要: 为探究2023年甘肃积石山Ms6.2地震前后地表热红外异常的时空演化特征，本文以积石山及其邻区为研究对象，选取2023年11月至2024年2月的MODIS热红外数据，采用劈窗算法反演地表温度，并构建历史同期背景场，结合背景差值与逐像元统计方法提取热异常信息。在此基础上，分析白天与夜间地表温度分布、昼夜温差及相对背景场偏离的空间特征，并通过时间序列对异常的阶段性演化进行刻画。结果表明：(1) 研究区地表温度具有明显的地形控制效应，白天温度整体高于夜间，低温区主要分布在高海拔或阴影区，高温区集中于低海拔或开阔地带；(2) 震前阶段Td-Tn与Tn-Tnm异常增强且具有一定连续性，震区附近出现相对突出的温差异常；(3) 时间序列中，Mean (Tn-Tnm)在震前出现明显突变，Slope指标在临震前后发生由正转负或由负转正的变化，震后仍呈一定波动并逐步趋稳。研究表明，夜间温度相对背景场的偏离对地震过程响应更敏感，基于MODIS的热红外异常检测可为地震热异常识别与时空演化分析提供参考。

Abstract: To investigate the spatiotemporal evolution characteristics of surface thermal infrared anomalies before and after the 2023 Jishishan, Gansu Province, Ms6.2 earthquake, this study takes Jishishan and its adjacent areas as the research region. MODIS thermal infrared data from November 2023 to February 2024 were selected, and the split-window algorithm was employed to retrieve land surface temperature (LST). A historical synchronous background field was constructed, and thermal anomaly information was extracted using background differencing combined with pixel-by-pixel statistical methods. On this basis, the spatial characteristics of daytime and nighttime LST distribution, diurnal temperature difference, and deviations from the background field were analyzed, and the staged evolution of anomalies was characterized through time series analysis. The results indicate that: (1) LST in the study area is significantly controlled by topography, with overall higher daytime temperatures than nighttime temperatures; low-temperature zones are mainly distributed in high-altitude or shaded areas, while high-temperature zones concentrate in low-altitude or open areas; (2) during the pre-seismic stage, Td-Tn and Tn-Tnm anomalies were enhanced and showed certain continuity, with relatively prominent temperature difference anomalies appearing near the epicentral area; (3) in the time series, Mean (Tn-Tnm) exhibited obvious abrupt changes before the earthquake, and the Slope indicator showed transitions from positive to negative or vice versa around the time of the earthquake, with certain fluctuations persisting after the earthquake and gradually stabilizing. This study demonstrates that nighttime temperature deviations from the background field are more sensitive to the earthquake process, and MODIS-based thermal infrared anomaly detection can provide reference for earthquake thermal anomaly identification and spatiotemporal evolution analysis.