Crustal Deformation Processes: The Long and Short of It
摘要
Gradual crustal deformation processes have been constantly deforming the earth’s surface. Understanding of these deformation processes in the present is the key to their reconstruction in the past. Such studies play a significant role to understand earthquake occurrences and identify potential zones for future earthquake occurrences. InSAR technique allows us to observe and measure short-term surface deformation patterns precisely and it can be modelled to determine the causative fault geometry and also to estimate the stress changes, particularly due to an earthquake. Although, long-term deformation processes may be observed through the geological and geomorphological studies of the area. These studies can be carried out using optical remote sensing images and Digital Elevation Models which can be used to identify evidences of past deformation at all spatial scales ranging from continents to small landmasses such as ponds, scarplets, terraces etc. As a corollary, landforms/landscapes have become an indispensable part of crustal deformation studies providing key insights by combining long-term records with short-term processes. The long-term deformation processes records are ingrained in geology and geomorphology, waiting to be discovered and interpreted whereas short-term processes refer to the range from few decades to current. It may be expected that these processes have operated in times when instrumentation and records were already available to some extent and any investigation into these may actually be data-driven. In the present study, we discuss the results of two earthquakes (1) Mirpur (2019) of magnitude 5.4 and (2) Afghanistan (2022) of magnitude 6.2; to evaluate the correlation between short- and long-term deformation patterns. The results show a reasonably good match, of course, both suffer from the incompleteness of record due to technical issues. However, in either case, for a better understanding of crustal deformation processes it is most suitable to complement diverse techniques over various spatial and temporal scales to arrive at the best possible outcomes.