Detection and potential early warning of catastrophic flow events with regional seismic networks

Abstract

Far away landslide detection A mass wasting and flood event on 7 February 2021 in Uttarakhand, India, killed more than 200 people and damaged two hydropower plants. Cook et al . discovered that teleseimic signals from the beginning of this event were recorded at different stations on a regional seismic network in northern India. The signals were observed up to 100 kilometers from the disaster and demonstrate the potential for these far-away monitoring stations to be useful for early warning. This discovery suggests a different way to monitor such remote Himalayan valleys for mass wasting hazards. —BG

Pre-collapse motion of the February 2021 Chamoli rock-ice avalanche, Indian Himalaya

“…During the morning of 7 February 2021, a 26.9 [95% confidence interval 26.5-27.3] Mm 3 wedge of rock and ice detached from the north face of Ronti, a 5500 m peak in the Uttarakhand Himalaya (Fig 1 .). This wedge then dropped around 1800 m to the Ronti Gad valley floor, where it continued down-valley towards the Rishiganga and Dhauliganga rivers and transformed into a debris flow (Shugar et al, 2021;Cook et al, 2021). The collapse block was composed of approximatively 80% bedrock and 20% glacier ice.…”

“…A viable triggering mechanism for the Chamoli landslide must explain both the lag between the initial instability and collapse, and the timing of the collapse -in the middle of the winter. Syn-collapse seismic signals show that there was no seismic trigger for the collapse (Pandey et al, 2021;Shugar et al, 2021;Cook et al, 2021). Nearby meteorological stations and reanalysis data reveal heavy snowfall and a 5 K positive temperature anomaly in the week preceding collapse, as well as a temperature inversion in the valley (e.g.…”

“…Every slope failure will exhibit a different range of pre-collapse signals, and new instabilities might be recognized in some cases. Even though the forecasting of individual events remains a challenge, these data have value for identifying zones of highest risk for in-situ monitoring or the installation of early-warning systems (Cook et al, 2021).…”

Potential seismic precursors and surficial dynamics of a deadly Himalayan disaster: an early warning approach

“…The seismic stations record high-quality seismic data with a high signal-to-noise ratio which allows for a detailed reconstruction of deadly avalanche dynamics. After the recent deadly event, numerous studies have been carried out, which states the geometry of detachment, mechanism of rock-ice avalanche, flow velocity, downstream devastation, post impact of flash flood based on remote sensing and regional seismic network 35 – 38 . The present article investigates and highlights the complete scenario of pre and post dynamics of the source zone of material failure.…”

Brief communication: Seismological analysis of flood dynamics and hydrologically-triggered earthquake swarms associated with storm Alex

“…In the past decade, near-river seismic monitoring has been conducted during moderate-magnitude floods (e.g., Burtin et al, 2016;Roth et al, 2016) and controlled small-magnitude flow events (Schmandt et al, 2013(Schmandt et al, , 2017. To date, extensive seismic investigations of large-magnitude flood events are rare and mostly associated with glacier lake outburst floods (Cook et al, 2018;Maurer et al, 2020) and natural hazard cascade (Cook et al, 2021). Yet, improved understanding of flood dynamics is crucial for early warning, risk mitigation, and modeling landscape evolution (Raynaud et al, 2015;Borga et al, 2019).…”