Volcanic Alert Bulletin TON-2012/32 - Tongariro Volcano
Updated: Fri Nov 23 2012 1:00 AM
GNS Science did not record any change of volcanic activity at Tongariro overnight. Tongariro can still erupt at any time with little or no warning.
NS Scientist Nico Fournier said: “It has been a quiet night in the park. On the GeoNet website, people may have noticed some earthquake-like spikes in rapid succession at some stations on Thursday evening. These were caused by lightning from thunderstorms in the Tongariro National Park. They were not real earthquakes and were not caused by any of the volcanoes."
Thunderstorm activity recorded at Oturere seismograph station yesterday. The regular blips in the middle rows of the drum are lightning strikes, not earthquakes.
The Aviation Colour Code remains at Orange and the Volcanic Alert Level at 2. GNS Science continues to closely monitor the situation.
Background
Lightning can be detected by the GeoNet monitoring network. Thursday evening’s thunderstorm in the Tongariro National Park showed up on stations across the Park. When lightning strikes the ground, it produces a lot of noise. This 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.
Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Orange indicates that a volcanic eruption is underway but with little or no ash being produced.
The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 2 indicates that a minor eruption has occurred.
Brad Scott, Nico Fournier Volcanologists