Gunung Hobal volcano (Iliwerung volcano, Lomblen Island, Indonesia): submarine eruption
A submarine eruption has likely occurred this morning in Indonesia. VSI raised the alert level of Iliwerung volcano from 1 (normal) to 2 (watch) following increased seismic and visual activity from an underwater flank vent called Gunung Hobal.
Di, 20. Aug 2013, 10:2110:21 AM | VON: T
Iliwerung volcano forms a peninsula on the south coast of Lembata (Lomblen) Island (East Indonesia). Mount Hobal (Gunung Hobal) is a submarine flank vent of Iliwerung located about 800 m from the coast. It has had several historic eruptions during which several temporary islands were formed.
The latest bulletin of VSI describes that the water around Hobal has recently shown significant color changes to yellow, intense bubbling and white steam plumes rising up to about 1000-2000 m from 7:14 local time this morning. Half an hour later, from 7:46 am, glow even began to be visible.
Strangely, no plume or other strong evidence of an eruption have been available so far from satellite data, except tiny spots visible on the latest images of the area which could be floating pumice (s. Culture Volcan's blog post)
It appears that the eruptive phase (if any) lasted only shortly, which could explain the absence of a clearly visible plume on satellite data.
VSI points out that there is an elevated risk of tsunamis associated with potential more eruptive activity, and recommends not to approach the coast within 30 m from the sea.
The last recorded eruptions of Gunung Hobal were in 1973-74 and between 17-18 August 1983.