Assessing Volcanic Hazard and Exposure at Obscure Volcanic Fields: A
Case Study from the Bolaven Volcanic Field, Laos
Abstract
South-east Asia is one of the most volcanically active places on Earth,
with the majority of the volcanoes located in Indonesia and in the
Philippines. Indochina (Myanmar, Cambodia, Laos, Thailand and Vietnam)
also hosts a certain number of volcanoes that for several reasons
(post-World War II conflicts, little accessibility due to dense
vegetation, no significant historical activity recorded), have been
little studied so far. Some of these volcanoes show evidence of recent
(Quaternary) activity, therefore, a systematic assessment of the threat
these volcanoes may pose to resident populations is needed in the
region. A recent study on the inferred location of the Australasian
meteorite impact (the largest known young meteorite on Earth) provided
an unprecedented amount of data for the Bolaven Volcanic Field in Laos,
in terms of geological mapping, location of vents, and over 30 absolute
ages of lava flows and vents. On this basis, besides additional data
obtained for this work, we used the Bolaven Volcanic Field as a case
study, to assess the potential exposure of populations and
infrastructure to lava flows in case of an eruption in the field. Key
results suggest that an overall area of ~5500 km2 is
potentially exposed to lava flows in case of eruption, including over
2000 km of roads, 400 km of power lines, two power stations and two
dams, and over 500 km2 of agricultural lands, with the potential to
affect about 300,000 people living in this area, and their main
businesses (hydropower and coffee production). In addition, the
abundance of water in this region may lead to life-threatening
explosions from phreatomagmatic eruptions. Finally, based on the data
available we provide a maximum estimate of the past eruption frequency
of the field, which is approximately 10,400 years. Our study provides a
number of techniques and approaches (remote sensing of potential sources
and past flows, lava flow simulations and open-access exposure data)
that can be used to assess hazards and exposure at other understudied
volcanoes.