M5.2 earthquake at Lake Taupo
Earthquakes in the Taupo region are often associated with existing faults caused by the spreading of the Taupo Volcanic Zone due to large scale tectonic processes.
Last night’s mainshock and aftershock sequence occurred along such a fault and are typical of other quake swarms in the region.
The M5.2, 7:02 pm mainshock at 5 km depth (4 September 2019) had over 4000 felt reports from around the North Island. This quake was followed soon after by a M4.5 aftershock that started off a sequence of 80 smaller aftershocks. There is no indication that these earthquakes are linked to a change in volcanic activity.
There have been three shallow earthquakes of M5.0 or greater in the Lake Taupo region since 1980, and over 40 greater than M4.0.
M5.2, 4 September 2019 earthquake location and locations of historic 1982 and 1985 earthquakes.
The greater Rotorua-Taupo area is a rift zone. A wedge of the earth’s crust is being stretched due to plate boundary processes. This stretching creates numerous faults which cause many earthquakes over time, including many smaller quakes clustered together as swarms.
Graphic shows rift zone ‘wedge’ and some of the faultlines associated with this. There are many faults in this rift zone.
Last night’s quakes were in a similar area to the recent smaller earthquakes we have been recording in the Lake Taupo area. We wrote a news story back in July on these quakes.
We have recorded 80 aftershocks since last night but the number seems to be declining. However, earthquakes can happen at anytime. Follow Civil Defence advice on what to do during an earthquake – Drop, Cover and Hold.
Drop, Cover and Hold
Attributable to – Yannik Behr, GNS Science Volcano Duty Officer
Media contact - Brad Scott, Volcanologist PH: 07 374 8211