M4.4 earthquake beneath Lake Taupo, more than 20 aftershocks, New Zealand

An earthquake with a magnitude of 4.4 struck beneath Lake Taupō, New Zealand on March 5, 2023, followed by more than 20 aftershocks. The Volcanic Alert Level remains at 1, which denotes minor volcanic unrest, and the Aviation Color Code is Green. Although there is no immediate risk, the potential for eruption hazards cannot be entirely ruled out, and it is essential that visitors and residents follow the recommended safety guidelines.

The Taupō Volcano in New Zealand continues to experience minor volcanic unrest after an M4.4 earthquake occurred beneath the lake on March 5, 2023. The earthquake rupture took place within 10 km (6.2 miles) of the surface and caused shaking felt mostly along the lake shore. More than 20 aftershocks have been located since the initial event, according to the GeoNet.¹

The number of earthquakes per week has been decreasing since November 2022 — after a strong and shallow M5.7 earthquake² — but the recent slight increase prior to the M4.4 event was observed. The GeoNet also noticed a small signal on their newly installed tsunami sensors in the lake during the earthquake, but further analysis is needed to determine its cause.

Despite the increase in earthquake activity, the volcano’s monitoring indicators remained stable, and there were no significant changes compared to the previous months of unrest. Thus, the Volcanic Alert Level remains at 1, which denotes minor volcanic unrest. The Aviation Color Code is at Green.

The GNS Science continues to actively monitor the volcano and collaborate with national and international experts to provide the most accurate interpretation of their monitoring data.

It should be noted that the Volcanic Alert Level represents the current level of volcanic activity and unrest, and it is not a forecast of future activity. Although Volcanic Alert Level 1 is generally associated with environmental hazards, the potential for eruption hazards cannot be entirely ruled out.

Taupō Volcano has a long history of volcanic activity and is an essential part of New Zealand’s natural environment.

A strong earthquake with a magnitude of 5.7 occurred beneath Lake Taupo on November 30, 2022, causing a small tsunami and minor local damage. The earthquake caused the largest ground movement ever recorded at the Horomatangi location. Over 600 aftershocks were located by December 7, with the largest being an M4.5.

There have been 17 previous episodes of unrest at Taupo over the past 150 years, but none have resulted in an eruption.

The last eruption at this volcano took place in the year 260 (VEI 6).

Ground shaking, landslides, volcanic activity and tsunami associated with M5.7 earthquake at Lake Taupō, New Zealand

Geological summary

Taupo, the most active rhyolitic volcano of the Taupo volcanic zone, is a large, roughly 35 km (21 miles) wide caldera with poorly defined margins. It is a type example of an “inverse volcano” that slopes inward toward the most recent vent location.

The caldera, now filled by Lake Taupo, largely formed as a result of the voluminous eruption of the Oruanui Tephra about 22 600 years before the present (BP).

This was the largest known eruption at Taupo, producing about 1 170 km³ (281 mi³) of tephra. This eruption was preceded during the late Pleistocene by the eruption of a large number of rhyolitic lava domes north of Lake Taupo.

Large explosive eruptions have occurred frequently during the Holocene from many vents within Lake Taupo and near its margins.

The most recent major eruption took place about 1 800 years BP from at least three vents along a NE-SW-trending fissure centered on the Horomotangi Reefs. This extremely violent eruption was New Zealand’s largest during the Holocene and produced the thin but widespread phreatoplinian Taupo Ignimbrite, which covered 20 000 km² (7 722 mi²) of North Island.³

References:

¹ Minor unrest continues at Taupō Volcano including a recent M4.4 earthquake. Volcanic Alert Level remains at Level 1 – GeoNet – March 7, 2023

² Ground shaking, landslides, volcanic activity and tsunami associated with M5.7 earthquake at Lake Taupō, New Zealand – The Watchers – December 14, 2023

³ Taupo volcano – Geological Summary – GVP

Featured image: Lake Taupo on March 6, 2023. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers