Mount Ruapehu experienced no significant changes following a two-day-long swarm of “small, relatively deep” earthquakes east of the volcano last week, volcanologists say.
More than 90 earthquakes, measuring less than magnitude 1, had been detected between 15-30km beneath the 2797m volcano’s northeastern flank early last week.
GNS Science duty volcanologist Geoff Kilgour said the temperature of Te Wai ā-moe, or the Ruapehu Crater Lake, remained stable at 12C.
“We continue to record emissions of volcanic gas indicating heat and gas flow from depth is occurring.”
The lake’s temperature had decreased from 17C since the last update in May, he said.
Observations from a June 8 visit included the lake overflowing and the presence of sulphur slicks on its surface – an indication of hydrothermal fluids entering the lake floor.
Kilgour said gas detectors showed low-level but continuous gas emissions of sulphur dioxide and carbon dioxide.
“Despite the swarm of nearby earthquakes, a lack of other observable changes at Ruapehu indicates that the volcano continues to exhibit typical background activity,” he said.
“When weather permits, we will be conducting further gas flights and sampling Crater Lake fluids to monitor any changes closely.”
The mountain was currently at Volcanic Alert Level 1 which indicated minor volcanic unrest.
Kilgour said Ruapehu was an active volcano and had the potential to erupt with little or no warning when in a state of minor volcanic unrest.