Yesterday morning, we reported how the swarm activity about 10 km west of Turangi had increased with 249 locatable earthquakes occurring in the previous week. That pulse of activity lead to a M4.5 at 6 km depth later in a day (12.58 pm). This was followed by a more typical aftershock sequence that included three M3+ events and numerous smaller earthquakes. The number of located events in the last week is now 614. The total number of events in the swarm has risen to 1245 since 13 February.

The events are occurring between about 4 and 10 km depth and most are in the 5-8 km depth range. The Taupo Volcanic Zone is a rifting area, growing wider each year by 6-9 mm. These earthquakes are located on the western boundary and are likely to be related to the long-term ‘tectonic’ stretching of the Zone. Several active faults are mapped in the GNS Science Active Faults database reflecting the ‘tectonic nature’ of this area. Currently, there are no indications that the earthquakes are related to volcanic activity, being located well away from the active volcanoes.

Earthquake swarms are a common feature of the Taupo Volcanic Zone. Every few years we have one in the greater Turangi area. This one has been ongoing since 13 February and has consisted of two major pulses of activity, with about 20 days between them. This second pulse is stronger with more events. Swarms come in a variety of forms and it is not possible to judge the future easily for them. Some have the stronger phase near the start, others in the middle and some swarms have the stronger activity at the end. We anticipate this one will continue in the short term. As usual, we continue to closely monitor the activity.