Combined Use of Satellite Data and Machine Learning for Detecting,
Measuring, and Monitoring Active Lava Flows at Etna Volcano
Abstract
Despite significant advances in monitoring of the development of active
lava flow fields, many challenges remain. Timely field surveys of active
lava flows could improve our understanding of the development of flow
fields, but data of sufficient accuracy, spatial extent and repeat
frequency have yet to be acquired. Satellite remote sensing of volcanoes
is very useful because it can provide data for large areas with a
variety of modalities ranging from visible to infra-red and radar.
Satellite sensing can also access remote locations and hazardous regions
without difficulty. Radar and multispectral satellite sensing data have
been shown that can be combined to map heterogeneous lava flows using
machine learning techniques, but a robust general model trained with
several different lava compositions has to be developed. Here, we
propose a robust, automatic approach based on machine learning
techniques for analysing open-access satellite data in order to map lava
flows in near-real time applicable to different kind of lava with
different thermal components (i.e., incandescent, cooling and cooled
lava component). We built a neural network model and trained it with a
set of satellite images (e.g., Sentinel-1 SAR, Sentinel-2 MSI and
Landsat 8 OLI/TIRS) of recent lava flows, and the relative labels of the
lava and background regions. In this way, the trained model becomes
capable to detect and map lava flows and to classify any new image, when
available. The relative output is a segmented image with lava and
background classes, obtained without an analysis made by a human
operator. This approach allows to segment lava flows with both hot spot
and cooling parts, and to recognize lava flows with different
characteristics in near-real time. The results obtained during the long
sequence of short-lived eruptive events occurred at Mt. Etna (Italy)
between 2020 and 2021 are shown.