Lava flow hazard modeling during the 2014–2015 Fogo eruption, Cape Verde

Abstract

Satellite remote sensing techniques and lava flow forecasting models have been combined to enable a rapid response during effusive crises at poorly monitored volcanoes. Here we used the HOTSAT satellite thermal monitoring system and the MAGFLOW lava flow emplacement model to forecast lava flow hazards during the 2014–2015 Fogo eruption. In many ways this was one of the major effusive eruption crises of recent years, since the lava flows actually invaded populated areas. Combining satellite data and modeling allowed mapping of the probable evolution of lava flow fields while the eruption was ongoing and rapidly gaining as much relevant information as possible. HOTSAT was used to promptly analyze MODIS and SEVIRI data to output hot spot location, lava thermal flux, and effusion rate estimation. This output was used to drive the MAGFLOW simulations of lava flow paths and to continuously update flow simulations. We also show how Landsat 8 OLI and EO‐1 ALI images complement the field observations for tracking the flow front position through time and adding considerable data on lava flow advancement to validate the results of numerical simulations. The integration of satellite data and modeling offers great promise in providing a unified and efficient system for global assessment and real‐time response to effusive eruptions, including (i) the current state of the effusive activity, (ii) the probable evolution of the lava flow field, and (iii) the potential impact of lava flows.

Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014–2015 Effusive Eruption at Fogo Volcano (Cape Verde)

“…The 2014-2015 eruption was jointly monitored by researchers from the University of Cape Verde (UNICV) and from INVOLCAN directly in field, and remotely by the Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo (INGV-OE) of Italy through satellite images [30,43].…”

“…From the end of December (Figure 2f) to the end of the eruption (Figure 2g), only small third-order ephemeral vents [3] were observed along the lava flow field, causing thickening of the proximal lava flow field [59], drainage of the main flows, and slight changes in the outline of the lava flow field. The eruption eventually ended on 8 February 2015, after a gradual decline of the output rate [30].…”

“…Figures 6 and 7 show the difference in volume between the TADR measured by satellite (data from [30]) and the SR calculated here from SO2 flux measurements [43]. It is worth noting that SO2 flux measurements started on 27 November, thus the SR estimates are lacking for the first three days of eruption.…”

“…TADR were calculated by considering, in the variability range of each lava parameter, the largest values [30]. Moreover, for the percentage of crystals and temperature variations, we used the recent constrained values [46].…”

“…In this paper, we present for the first time an estimation of the total volume endogenously intruded within the lava flow field of the Fogo 2014-2015 eruption. We obtained this estimate by comparing results of time averaged discharge rate (TADR) from satellite measurements [30] and of magma supply rate (SR) from the source as retrieved from daily measurements of SO 2 flux, which is related to the amount of degassing magma intruded within the system [31,32]. Given that satellite images only detect surface emplacement of lava, and that SO 2 flux instead is related to the total magma volume stored in the source region [32] and feeding the eruption, the difference between the two should give an estimation of the magma intruded within the lava flow field and responsible for its inflation and supplying lava tubes.…”