Whakatane Earthquake Swarm

A swarm of shallow earthquakes struck off the coast near Whakatane overnight.

Monday, 25th January 2016

Residents of Whakatane felt several earthquakes last night as a swarm of earthquakes struck off-shore, 10 km north-west of the Bay of Plenty town.

The earthquake swarm started at 9:18 p.m. when a magnitude 2.6 earthquake struck 10 km north-west of Whakatane at a depth of 1 km. A magnitude 2.7 quake followed nearly two minutes later, at a depth of 2 km.

Four more magnitude 2 earthquakes occurred before the largest member of the swarm struck at 9:32 p.m. This was a magnitude 3.3 earthquake, 7 km deep. Another two quakes of magnitude 2 and a magnitude 1.7 quake struck before a magnitude 3.2 earthquake struck at 9:47 p.m. Four more quakes of second magnitude struck before the swarm ceased activity at 10:46 p.m.

Of the 14 earthquakes, GeoNet reports that the two magnitude 3 events were most widely felt, with reports from the public being filed from Tauranga to Opotiki.

GeoNet issued a brief summary of the swarm late last night.

Two earthquake swarms struck the area in 2010. The first period of activity occurred on May 15th, and another on May 19th.

GeoNet advises that the earthquake swarm is caused by tectonic activity and is not associated with nearby volcanic activity. Earthquake swarms are common in the Taupo volcanic zone, a wedge-shaped area that extends north from Lake Taupo and into the Bay of Plenty. The Earth’s crust in this area of the North Island is being spread apart by interaction between the Pacific and Australian tectonic plates, causing East Cape to slowly move eastward away from the Coromandel Peninsula.

[Compiled from data supplied by GeoNet.]

Leave a Reply