Internal Structure of Four Rock Glaciers in the Northern Tien Shan from Geophysical Investigations

The cryosphere in Central Asia is critically important as a source of water. Widespread glacier mass loss has been observed across the Tien Shan in response to rising temperatures, raising concerns over future water resources. The Northern Tien Shan, situated along the border of Kazakhstan and Kyrgyzstan hosts almost 700 rock glaciers, including a number of notably large, fast flowing landforms, connected to clean ice glaciers. Despite their prevalence, little is known about the volume and distribution of ice within these rock glaciers. Previous studies have highlighted the potential hydrological significance of rock glaciers both globally and in the Tien Shan, but field data to support this assumption remains limited, particularly outside of Europe.Here, we present the results of geophysical investigations on four glacier or glacier-forefield connected rock glaciers in the Ulken Almaty Valley, Kazakhstan, conducted in July 2024. The investigations aim to provide key information on the internal structure of these rock glaciers, focusing on the internal architecture and spatial distribution of ice. We conducted Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) surveys using a 48-electrode ERT device and a 100MHz GPR. ERT surveys were conducted on the two larger rock glaciers (Morennyi and Gorodetsky), whilst GPR surveys were conducted across all four rock glaciers. In total, 10 ERT profiles with a combined length over 3 km and approximately 10 km of GPR profiles were collected. Initial results reveal areas of high ice content with a heterogenous distribution related to morphological features. This research builds on previous remote sensing work examining rock glacier surface kinematics, aiming to better understand the relationships between surface flow processes and rock glacier internal structure.