Validation of an integrated satellite-data-driven response to an effusive crisis: the April–May 2018 eruption of Piton de la Fournaise

Abstract

Satellite-based surveillance of volcanic hot spots and plumes can be coupled with modeling to allow ensemble-based approaches to crisis response. We complete benchmark tests on an effusive crisis response protocol aimed at delivering product for use in tracking lava flows. The response involves integration of four models: MIROVA for discharge rate (TADR), the ASTER urgent response protocol for delivery of high-spatial resolution satellite data, DOWNFLOW for flow path projections, and PyFLOWGO for flow run-out. We test the protocol using the data feed available during Piton de la Fournaise's April-May 2018 eruption, with product being delivered to the Observatoire du Piton de la Fournaise. The response was initialized by an alert at 19:50Z on 27 April 2018. Initially DOWNFLOW-FLOWGO were run using TADRs typical of Piton de la Fournaise, and revealed that flow at >120 m 3 /s could reach the island belt road. The first TADR (10-20 m 3 /s) was available at 09:55Z on 28 April, and gave flow run-outs of 1.2-2.5 km. The latency between satellite overpass and TADR provision was 105 minutes, with the model result being posted 15 minutes later. An InSAR image pair was completed six hours after the eruption began, and gave a flow length of 1.8 km; validating the run-out projection. Thereafter, run-outs were updated with each new TADR, and checked against flow lengths reported from InSAR and ASTER mapping. In all, 35 TADRs and 15 InSAR image pairs were processed during the 35day-long eruption, and 11 ASTER images were delivered.

Thermal Remote Sensing for Global Volcano Monitoring: Experiences From the MIROVA System

“…Many effusive eruptions show a characteristic exponential decrease of effusion rates over time, ascribed to elastic or inelastic processes occurring within the decompressing magmatic system (Wadge, 1981;Coppola et al, 2017). In Figure 8a we show the TADR and erupted volumes, reconstructed through the MIROVA data, for the April 2018 eruption of Piton de la Fournaise (Harris et al, 2019) that can be considered as archetypal for this type of trend. Taking into account the uncertainty in the TADR estimates (typically between 30 and 50%; Coppola et al, 2019b), several types of predictions are possible.…”

“…Stationary, waning or intensifying trends obviously have different implications on the evaluation of the hazards and can be used (modeled) to define future eruptive scenarios, and possibly to make forecasts. At Piton de la Fournaise (La Réunion Island), the knowledge of the effusion rate trend (derived from thermal data), in combination with previously generated models of the likely lava flow path, has been useful to predict whether the flow will tend to lengthen or shorten, and whether the lava flows will reach the sea, cutting the national road that goes around La Réunion Island (Harris et al, 2017(Harris et al, , 2019. Moreover, by comparing this variable with the gas flux and deformation rate, it is possible to analyze the balance of the erupted/degassed material and eventually to quantify magmatic intrusions or endogenous growth .…”

“…At basaltic volcanoes equipped with a large ground-based monitoring network, such as Stromboli, Etna, Piton de la Fournaise, etc., MIROVA is commonly used to estimate timeaveraged lava discharge rates (TADR) and erupted volumes in near real time Laiolo et al, 2019), to define imminent eruptive scenarios and to model the path and length of lava flows (Harris et al, 2017(Harris et al, , 2019.…”

“…Taking into account the uncertainty in the TADR estimates (typically between 30 and 50%; Coppola et al, 2019b), several types of predictions are possible. For example, the initial flow rate (Q 0 ) can be used (as soon as the MODIS data has been processed) within an effusive response protocol (Harris et al, 2017(Harris et al, , 2019, to timely provide the observatory flow path projections and maximum run-out of the emplacing lava flow (Figure 8b).…”

“…(a) Middle Infrared Observations of Volcanic Activity-derived TADR (blue circles) and cumulative volume (red circles) provided to the Observatoire Volcanologique du Piton de la Fournaise (OVPF) during the April 2018 eruption. Q 0 is the initial flow rate, used to model the maximum runout of the emplacing lava flow (modified fromHarris et al, 2019). (b) Lava flow inundation map derived from ingestion of MIROVA-derived TADR into DOWNFLOW-PyFLOWGO models.…”