Exploring tectonic strain accumulation and release patterns in the Pamir region using Sentinel-1 InSAR data

The Pamir Range in Central Asia accommodates a significant portion of deformation resulting from the ongoing collision of India with Eurasia. The region hosts active faults that are fast-slipping and geomorphically well-expressed, and that have witnessed large- and moderate-magnitude earthquakes during the instrumental period. For example, the Vakhsh and Darvaz faults that bound the Pamir to the north and west, respectively, are characterized by some of the fastest slip rates in continental Asia (> 10 mm/year during Holocene time). Several large-magnitude earthquakes have been recorded within the Pamir, including the 1911 M 7.7 Sarez Lake and 2015 M 7.2 Sarez/Murghab earthquakes. These features and events present a natural laboratory in which to test fundamental questions regarding the nature of strain accumulation and release at collisional plate boundaries. Yet the region remains under-explored from both ground-based and remote sensing perspectives due to its relative inaccessibility, steep terrain, and seasonal changes in snow cover. In this study, we use 7 years of Copernicus Sentinel-1 satellite radar interferometry (InSAR) data processed using a combined permanent scatterer (PS) and distributed scatterer (DS) approach. This approach is more robust in the Pamir ranges where areas of low coherence (e.g., due to snow) can lead to errors in the timeseries displacement measurements.

We use the ground surface velocity maps (averaged over the 7-year observation period) computed from the InSAR data to explore tectonic strain accumulation and release patterns. Spatial patterns of deformation will better constrain the kinematics and relative activity of different faults in the region. Comparison of the geodetic data to paleoseismic earthquake records and offset geomorphic features will provide insights into the temporal behavior the fault network. These combined datasets will address questions including: What portion of the India-Eurasia strain budget is accommodated on mapped, throughgoing tectonic structures such as the Vakhsh and Darvaz faults? What effects have recent, large-magnitude earthquakes (e.g., along the Sarez-Karakul fault system) had on the interseismic strain accumulation rates of surrounding faults? Have the faults experienced significant changes in strain accumulation and release rates over time, as indicated by discrepancies between geodetic and geologic slip rates?