Icequakes on the Urumqi Glacier No. 1, China and their relations with solid tide and environmental changes

Icequakes, micro-seismicity caused by glacier deformation and motion, provide important information to study glacier dynamics and its responses to environmental changes at various temporal and spatial scales. In this study, we apply a multi-dimensional autoregressive maximum-likelihood algorithm to obtain 12 icequake templates on the Urumqi Glacier No. 1, China, and detect 65,363 icequakes through template matching. Centroid location of the 12 templates indicate that most icequakes are caused by surface crevasses inside the glacier, which are characterized by dominant surface waves. The icequakes show seasonal variation with more events in summer because of faster ice flow due to high temperature and precipitation. In winter, however, the icequakes, on par with those in summer, suggest considerable glacier growth in cold weather. Because of higher ice flow velocity due to low tide, the number of icequakes has two daily peaks which seems to negatively correlate with semi-diurnal solid tide.

冰震（Icequakes）是由冰川变形与运动引发的微地震活动，可为研究冰川动力学及其在不同时空尺度下对环境变化的响应提供关键信息。本研究采用多维自回归极大似然算法，在中国乌鲁木齐一号冰川（Urumqi Glacier No.1）上构建了12个冰震模板，并通过模板匹配法检测到65363次冰震事件。12个模板的质心位置分析显示，绝大多数冰震由冰川内部的表层裂隙引发，这类冰震以面波为主要特征。冰震活动呈现显著季节变化：夏季事件数量更多，这是由于高温与降水促使冰川运动速率加快。但冬季的冰震事件数量与夏季基本持平，表明寒冷天气下冰川仍存在显著增生现象。由于固体潮汐作用引发的冰川流速升高，冰震数量每日呈现两个峰值，且该峰值似乎与半日固体潮呈负相关关系。