nothing to see here, move along please
Volcano graph lit up by lightning
[link to home.nzcity.co.nz
Spikes on seismographs around Mt Tongariro seen on the GeoNet website were caused by lightning strikes and not the mountain, which was quiet overnight.
Share on twitter Share on email Share on facebook Share on print More Sharing Services
23 November 2012
A series of spikes in seismograph measurements at Tongariro National Park overnight were due to lightning and not volcanic activity, scientists say.
Mt Tongariro was quiet overnight on Thursday, about a day and a half after the mountain's Te Maari crater spewed ash and gas up to 4km in the air in Wednesday afternoon's eruption.
People watching the GeoNet website may have noticed some spikes at the Oturere seismograph station but GNS scientist Nico Fournier says they have nothing to do with the earth.
"These were caused by lightning from thunderstorms in the Tongariro National Park," Dr Fournier said.
"They were not real earthquakes and were not caused by any of the volcanoes."
He said lightning creates a lot of noise when it strikes the ground that can be detected by seismometers and acoustic sensors.
"The nature of signal recorded differs from that caused by volcanoes, allowing scientists to discriminate them from real earthquakes."
The GNS team was hoping to take measurements of gases coming from Mt Tongariro by sending a plane up to the mountain but Dr Fournier said weather on Friday could make that difficult.
"We need a good view and ... today's not looking essentially promising," he told Radio New Zealand.
Dr Fournier said the volcano had been remarkably quiet overnight, but that doesn't mean it's calming down.
"The volcano can pretty much erupt at any time. The last eruption was only a few days ago so it's still pretty unstable, and it can occur with little or no warning at all."
He said Mt Ruapehu had also been quiet but there was still a slightly elevated risk.