Monitoring ground movement at Volcán de Colima, Mexico, using Sentinel-1 data and SqueeSAR®

Abstract

Volcán de Colima is a highly active stratovolcano in western Mexico, which presents a significant hazard to over 300 000 people who live within c. 40 km of the volcano. Because of its persistent activity, the volcano is actively monitored and researched, and understanding the patterns of behaviour is vital to accurate hazard assessment. Sentinel-1 synthetic aperture radar (SAR) images from ascending and descending orbits allow 1D and 2D ground motions to be retrieved using multi-interferogram techniques. SqueeSAR®’s unique processing allows a better characterization of subtle ground movements in remote, rural mountainous areas compared with many other multi-interferogram techniques. A dataset of 147 SAR scenes (2017–19) has been processed to show patterns of lava subsidence (<150 mm of downward vertical deformation over 2 years), as well as volcano deflation and apparent westward lateral movement. These data indicate that viscous andesitic lava flows may remain mobile for years following eruption and emplacement, and that the entire volcanic edifice is subsiding. Despite the apparent quiescence, volcanic edifices can remain highly dynamic after the termination of explosive or effusive activity. We interpret that the western flank of Volcán de Colima may become steeper with time and may be of long-term concern for hazard assessment activities.