Work

NISAR offsets measure pre-failure motion but do not single out the Bhote Koshi avalanche source

Year: 2026

Type: preprint

Abstract: Whether catastrophic ice–rock detachments are preceded by measurable surface motion decides whether satellite geodesy can contribute to early warning. We analyse five consecutive NISAR L-band pixel-offset pairs spanning the 26 August 2026 Bhote Koshi ice–rock avalanche, Nepal, and screen the full 116,707 km² footprint for coherently moving surfaces. In the interval closing seven days before failure the source moved 0.96 m in 24 days along the topographic fall line, and the signal survives a matched-magnitude control; but against size-matched random regions no pre-event interval reaches the 95th percentile on directional coherence or displacement, and no interval shows acceleration. The pair spanning the failure decorrelates. A blind footprint-wide screen recovers the source among 101 validated zones of downslope motion, 93 of them inventoried glaciers, and does not distinguish it by magnitude, persistence or coherence. Motion at a future source is measurable before failure; it is not diagnostic of failure.

Source: Research Square

DOI: 10.21203/rs.3.rs-11022365/v1

Author: Sansar Raj Meena

Institution: National Institute of Oceanography and Applied Geophysics

Language: English

Topic: Landslides and related hazards

Subfield: Management, Monitoring, Policy and Law

Field: Environmental Science

Domain: Physical Sciences

Open Access status: green

Funders: National Aeronautics and Space Administration, European Commission, Indian Space Research Organisation, Ministero dell'Università e della Ricerca

Awards: G6019297537, G6025922736