Abstract
Lahars are one of the greatest hazards at many volcanoes, including Volcán de Fuego (Guatemala). On 1 December 2018 at 8:00pm local Guatemala time (2:00:00 UTC), an hour-long lahar event was detected at Volcán de Fuego by two permanent seismo-acoustic stations along the Las Lajas channel on the southeast side. To establish the timing, duration, and speed of the lahar, infrasound array records were examined to identify both the source direction(s) and the correlated energy fluctuations at the two stations. Co-located seismic and acoustic signals were also examined, which indicated at least 5 distinct energy pulses within the lahar record. We infer that varying sediment load and/or changes in flow velocity is shown by clear fluctuations in the acoustic and seismic power recorded at one of the stations. This particular event studied with infrasound provides insight into how lahars occur around Volcán de Fuego.
Highlights
Lahar is an Indonesian term to describe mobilized pyroclastic mudflows on or near a volcano
In this study we use data recorded from a secondary rain-triggered lahar on 1 December 2018 by two permanent, telemetered seismo-acoustic stations located along the Las Lajas drainage; these instruments are part of a larger network installed at Volcán de Fuego to monitor the drainages to the south of the volcano (Figure 2A–B)
Preceding the lahar event (~ : 6: – : : UTC), sensors picked up thunder and other possible stormrelated noise, such as wind. [E and F] Lahar event infrasound data for channel of the infrasound sensors at both stations overlain on the vertical component (z) of the seismic data
Summary
Lahar is an Indonesian term to describe mobilized pyroclastic mudflows on or near a volcano. Major initiation mechanisms include transformations from debris avalanches [e.g. Mount St. Helens, USA: Scott 1988], rapid melting of ice and snow during an eruption [e.g. Nevado del Ruiz, Columbia: Pierson et al 1990], outbreaks of crater lakes (or other impounded bodies of water) [e.g. Mt. Kelud, Indonesia: Thouret et al 1998], and rainfall on unconsolidated tephra deposits [e.g. Besides the addition of water, influence the initiation of a rain-triggered lahar, including: (1) slope instability and channel gradient driven by gravitational forces [e.g. Lavigne and Thouret 2003; Pierson et al 2013]; (2) the volume and thickness of pyroclastic material and tephra deposits [e.g. Infrasound has been utilized to detect and track lahars [Johnson and Palma 2015], and other types of non-volcanic debris flows and surficial mass movements [Allstadt et al 2018; Marchetti et al 2019]. This study highlights the capabilities of infrasound in detecting and tracking lahars, as well as distinguishing the hydrological and geomorphic pulses and surges that occur within the flow
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