September 17th, 2024
GeoNet has reported a decrease in the number of earthquakes at Taupō Volcano over the past few weeks, and the seismic activity is almost back to what is typically seen, according to a news release today. However, the uplift of the central part of Lake Taupō continues, and the volcanic alert level remains at 1.
Unrest period and earthquake activity
Since May 2022, GeoNet has recorded over 1750 shallow earthquakes under Lake Taupō. The largest earthquake to date occurred on November 30, 2022, measuring 5.7 magnitude at around 9 km below the lake surface. About 825 or 47% of all earthquakes since May 2022 were aftershocks associated with this main event. Four other earthquakes above magnitude 4 were also recorded, according to GeoNet.
The current unrest episode has lasted for about 10 months, and the rate of shallow earthquakes has decreased overall since the start of 2023, with seismic activity almost back to levels seen before May 2022.
Taupō Volcano remains in minor unrest despite earthquake activity having almost returned to normal. Volcanic Alert Level remains at Level 1. Read the full bulletin here: https://t.co/KCQAr3D0kj pic.twitter.com/Yc6gxUn8i8
— GeoNet (@geonet) April 5, 2023
Uplift at horomatangi reef
GeoNet has observed uplift at Horomatangi Reef at an average rate of about 60 mm per year since the start of 2022.
Unrest meaning and historical data
GeoNet media release notes the long-term scientific research at Taupō volcano suggests the presence of a “magmatic mush” at 5 – 11 km beneath Lake Taupō, which is a mixture of molten magma and solidified crystals. The current unrest episode is caused by an increase in the rate of magma supply into the mush body, with similar processes occurring during earlier unrest episodes.
GeoNet has recorded at least 18 episodes of unrest in the last 150 years, and none of them have resulted in an eruption. The transfer of heat and fluids into the mush body creates stress at depth, leading to more or stronger earthquakes, as observed over the last 10 months.
Volcanic alert level and aviation colour code
The volcanic alert level at Taupō volcano remains at 1, and the aviation colour code is green. The volcanic alert level reflects the current level of volcanic unrest or activity and is not a forecast of future activity. While Volcanic Alert Level 1 is mostly associated with environmental hazards, the potential for eruption hazards also exists.
GeoNet continues to actively monitor the volcano and will provide updates as more information becomes available. The decision to lower the alert level will depend on the rate of uplift, earthquake activity, and other relevant information.
Volcanic unrest hazards occur on and near the volcano, and may include steam eruptions, volcanic gases, earthquakes, landslides, uplift, subsidence, changes to hot springs, and/or lahars (mudflows).
Volcanic environment hazards may include hydrothermal activity, earthquakes, landslides, volcanic gases, and/or lahars (mudflows).
Ash, lava flow, and lahar (mudflow) hazards may impact areas distant from the volcano.
Note: An eruption may occur at any level, and levels may not move in sequence as activity can change rapidly. This system applies to all of New Zealand's volcanoes. The Volcanic Alert Level is set by GNS Science, based on the level of volcanic activity.
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