Spatially heterogeneous glacier elevation change in the Jankar Chhu Watershed, Lahaul Himalaya, India derived using ASTER DEMs

This study investigates elevation change (dh) and geodetic mass budget of glaciers in the Jankar Chhu Watershed (JCW), Lahaul Himalaya, India, based on the difference in ASTER DEMs during 2002–2018. Glacier-wide spatially heterogeneous dh patterns were evaluated in the context of morphological and topographical settings. During 2002–2018, glaciers show a mean annual elevation change rate (dh/dt) of −0.38 ± 0.10 m a−1, resulting in a specific mass budget of −0.32 ± 0.09 m w.e.a−1, close to the previously reported estimates in western Himalaya. Nearly stagnant thick debris-covered tongue (>10% debris cover) characterized by melt hotspots exhibits maximum dh at up-glacier instead of the terminus. Debris-free glaciers (dh near the terminus. Spatially heterogeneous dh under varying debris cover is interpreted as an insulating effect of debris thickness as validated by field measurements. We suggest that elevation change of debris-covered glaciers cannot be generalized and glacier-wide spatially detailed mapping of dh is necessary to better understand the control of different surface morphology under warming climatic conditions in the western Himalayas. We present a spatially heterogeneous elevation change rate of 33 glaciers (150.9 km2) in the Jankar Chhu Watershed (JCW), Chandrabhaga basin, Western Himalaya based on the differences of ASTER digital elevation models (DEMs).We estimate the altitude-dependent elevation change of glaciers under varying debris thickness and surface morphology.Glaciers in the JCW show mean dh/dt of –0.38 ± 0.10 m a−1, resulting in a specific mass budget of –0.32 ± 0.09 m w.e.a−1, close to the previously reported estimates in western Himalaya.Debris-covered ice exhibits higher elevation change than debris-free ones.Thick debris-covered tongues show maximum surface lowering at up glaciers while debris-free tongue exhibits maximum lowering near the terminus.Debris thickness controls the altitude-wise spatial elevation change pattern in the JCW. We present a spatially heterogeneous elevation change rate of 33 glaciers (150.9 km2) in the Jankar Chhu Watershed (JCW), Chandrabhaga basin, Western Himalaya based on the differences of ASTER digital elevation models (DEMs). We estimate the altitude-dependent elevation change of glaciers under varying debris thickness and surface morphology. Glaciers in the JCW show mean dh/dt of –0.38 ± 0.10 m a−1, resulting in a specific mass budget of –0.32 ± 0.09 m w.e.a−1, close to the previously reported estimates in western Himalaya. Debris-covered ice exhibits higher elevation change than debris-free ones. Thick debris-covered tongues show maximum surface lowering at up glaciers while debris-free tongue exhibits maximum lowering near the terminus. Debris thickness controls the altitude-wise spatial elevation change pattern in the JCW.</p

DataSheet1_Paleoseismology of the Marquesado-La Rinconada thrust system, Eastern Precordillera of Argentina.PDF

Excavated trenches at two sites across the Marquesado–La Rinconada fault system along the eastern Precordilleran front south of San Juan, Argentina, reveal the earthquake history of this rapidly urbanizing region. Interpretation of earthquakes is based on both the generation of colluvial wedges and upward fault terminations, as well as folding events in fine-grained alluvium ponded behind upslope-facing fault scarps. The ages of the past five interpreted earthquakes at the Loma Negra site are E1 at 2.8 ± 2.8 ka, E2 at 7.1 ± 1.5 ka, E3 at 9.6 ± 1.3 ka, E4 at 14.4 ± 2.1 ka, and E5 at 17.2 ± 3.1 ka. At the Jejenes sites, we documented event ages of 2.7 ± 0.1 ka, 3.9 ± 0.6 ka, 5.9 ± 1.3 ka, and 11.4 ± 4 ka. These results indicate that the recurrence interval along the Marquesado–La Rinconada fault zone averages several thousand years. The inferred displacements at the Jejenes site are about 1.1 m for E1, E3, and E4 and 2.1 m for event E2, whereas the displacements at Loma Negra averaged about 1 m, but the most recent event displays less slip. Notably, the older events seem to have been larger and emergent, whereas the youngest event appears to have been smaller and blind in the ponded sediment; this may partially explain the poor expression of classic colluvial wedges associated with some events. Despite the fact that active surface faulting has an uncertain relationship with the primary seismic sources at depth in the crust, past and future events of Mw ∼7.5 are consistent with the length scale of active deformation, the ∼1–2 m slip per event scale of these ruptures, and the size of historical earthquakes.</p