Mt. Ruapehu’s Unrest Declines

Cooling of the hydrothermal system at Mt. Ruapehu indicates that the recent period of unrest is drawing to a close. Crater lake temperatures have fallen, gas emission are reduced and volcanic tremor has declined.

GNS Science issued an alert bulletin for Mt. Ruapehu yesterday, the 21st of July 2008, reporting that the signs of elevated unrest at the central North Island volcano had declined.

The volcano’s crater lake, which has hovered at temperatures ranging between 34 ºC and 37 ºC in recent months had fallen to 23.3 ºC on July 15th. Sulphur dioxide and carbon dioxide gas levels, which had shown significant increases and were ten times the normal levels on June 12th, have now reduced to normal background levels.

Volcanic tremor, which had been at a slghtly increased level, had also declined to typical background levels for the volcano.

The bulletin concluded that the phase of unrest appears to be over, but that future eruptions of Mt. Ruapehu could occur without warning.

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