This study, motivated by the flood disaster that took place at the glaciated region in Rishi Ganga Basin of Nanda Devi Biosphere Reserve (NDBR), Uttarakhand on 7th February 2021, intends to identify the altitudinal and sequential changes in the glacier region using satellite imageries. Our results suggest that 21.50 km2 and 34.70 km2 glacier area was lost from the region during the period 1976–2013 and 1976–2020 respectively. Besides this, out of the 106 High Altitude Glacial Lakes (HAGLs) found at an altitude of 4500 m above mean sea level (amsl), 14 potential spots are identified which can be a reason for future calamities. Our analysis of snow cover extents for the decade 2010–2021 suggests a considerable decrease of (16–28%) in winter snow cover. The unpredictable temperature fluctuations especially during the last few decades have also affected the freezing and thawing processes in the high-altitude areas. The changing behavior of the weathering processes quite often results in landslides, a major reason for disasters in the higher Himalaya. There is, thus, an urgent need to identify the high-risk sites in higher Himalaya which may be potential zones for future landslides. In anticipation to mitigate the resulting damages, the study emphasizes developing an early warning system based on geospatial technology to minimize loss of life, particularly for the workers employed in the engineering projects in the vicinity of the risk zone.

Sills and hydrothermal vents are commonly observed in sedimentary basins. However, not all sills could generate overlying hydrothermal vents, and whether a sill generates a hydrothermal vent or not is still poorly constrained. In this study, a large number of sills and hydrothermal vents are observed, using high-resolution reflection seismic data in the Qiongdongnan Basin of northern South China Sea. These sills are characterized by saucer or linear shapes and present as isolated sills or sill swarms, roughly being larger with buried depth increase. More importantly, the hydrothermal vents are mainly related to the underlying sills intruding into the shallow strata (buried depth <1.4 km), which suggests that magma intrusion depth (from paleo-seabed to the tip of sill) plays an important role on the formation of hydrothermal vents. The duration of magmatism lasted for ∼5 Ma from ∼11.6 Ma to ∼5.7 Ma with peak occurring at ∼8.2 Ma, judging from the spans of hydrothermal vents in the sedimentary strata. This study reports the intense magmatism in the eastern Qiongdongnan Basin for the first time, which extends the distribution of post-rift magmatism in the South China Sea and benefits to explore the mysterious origin of post-rift magmatism. The intense magmatism would also influence the maturity of source rock and hydrocarbon migration in such a petroliferous basin. Moreover, this study also highlights that shallow emplacement of sill is advantageous for the occurrence of hydrothermal vents due to the heating of unconsolidated/less consolidated strata by magmatic sills.