Abstract
Temperature measurements have been made in the Lokbatan crater at three locations after the explosion of 25 October 2001. The measurements were made at depths of 0.5m, 1.0m and 1.5m into the mud ejected at the time of the explosion, and have continued to be made at intervals of approximately one month.
The temperature measurements do not seem to indicate a steady cool-down with time, but rather an initial cooling for about 150 days after the primary explosion, followed by more recent re-heating events. This pattern of events is likely consistent with the on-going supply of gas to keep the central crater flame burning (at about 0.5m high over an area of about 1m2, as observed in late May, 2002); and also consistent with sporadic flame outbursts since the primary explosion, as also observed.
Two regional lines of temperature measurements across the volcano region in roughly north-south and east-west directions, respectively, to distances of several km, indicate that the ejected mud cooled rapidly to background temperatures over a timescale of a month or so, unlike the crater region. Background measurements prior to the explosion from producing wells on the flanks of the volcano indicate heat flux focusing centred on the volcano, while rock ejecta indicate mud production from the Upper Cretaceous at depths of several km.
The initial flame was around 100 m in diameter and approximately 400 m high, lasting about 24 hours; the ejected mud covers the crater area to a distance of more than 150 m in all directions to a depth of several metres. Oil production from the flanks of the mud volcano was unperturbed by the explosion.
Both geodynamic and gravimetric records have also been made in the general region. The detailed information and inferences they provide argue for a “sloppy” unconsolidated region at around 3–6 km depth that may be the source of both mud and entrained gas flow. A more quantitative discussion of these investigations will be reported later.
Currently, thermal observations in the Lokbatan crater continue on a roughly monthly basis (weather permitting) in the hope that better discrimination between competing thermal models (cooling versus re-heating) may be sharpened with such data over the next few years.