ausblenden:
Schlagwörter:
geyser geothermal field; slope instability; explosion hazard
Zusammenfassung:
Geyser geothermal fields are scenic volcanic landforms that often contain tens to hundreds
of thermal spot vents that erupt boiling water or contain bubbling mud pools. The fields are
potentially hazardous sites due to boiling water temperatures and changes in vent locations and
eruption dynamics, which are poorly understood. Here we report on the rapid and profound changes
that can affect such a geyser field and ultimately lead to a dangerous, unanticipated eruption. We
studied the Geyser Valley, Kamchatka Peninsula, which is a field of geysers and other thermal
features and boiling pools. Using high-resolution tri-stereo satellite data and unmanned aerial
systems (UAS) with optical and thermal infrared cameras in 2018 and 2019, we were able to identify a
newly emerging explosion site. Structure-from-motion analysis of data acquired before and after the
explosion reveals morphological and thermal details of the new vent. The explosion site produced
an aureole zone of more than 150 m3 of explosively redeposited gravel and clay, a slightly elliptical
crater with a diameter of 7.5 m and a crater rim 0.30 m high. However, comparison with archives of
photogrammetric data suggests that this site was thermally active years earlier and contained a crater
that was obscured and covered by landslides and river sediments. The results allow us to develop a
conceptual model and highlight the hazard potential of thermal features buried by landslides and
clastic deposits. Sudden explosions may occur at similar sites elsewhere, highlighting the need for
careful assessment and monitoring of geomorphological and hydrological changes at geyser sites in
other regions.
