New Zealand Shaken By Earthquake Swarm

Hours after a  7.3 earthquake struck east coast of Honshu, Japan, New Zealand has been shaken by a widespread earthquake swarm which was felt in much of the country. The quake epicentres stretched from Christchurch in the south to Morrinsville in the North.

The USGS reported the largest earthquake as a M6.3, 21 ESE of Tokoroa

earthquake storm

Geonet published a map of this morning’s earthquake swarm

Quake were felt across

Tokoroa quake was felt across New Zealand

New Zealand’s Geonet site reported the quake to be a subduction zone earthquake , M5.8, 20km SE of Tokoroa.

  • Public Id: 2012p923684
  • NZDT: Saturday, December 8 2012 at 7:19:06 am
  • Intensity: moderate
  • Depth: 175 km
  • Magnitude: 5.8
  • Location:  20 km south-east of Tokoroa

Yesterday Canterbury experienced its largest earthquake for some weeks, a shallow 3.6 centred 25km west of Christchurch.

The quakes were immediately reported by the Trademe community, a person near Wellington wrote

“Heard it coming here in Kapiti and it was fast moving. Seemed to go on and on with the more serious shakes in the middle. Initial wondering was if the mountain had finally erupted but don’t think so.”

Another in New Plymouth said

felt in New Plymouth… i never feel quakes!

Activity is still continuing at Mount Tongario which erupted on 21 November.

In August we blogged about magma rising beneath Mt Tongariro, asking it it were linked to a magnitude 7 earthquake  60km south of the Taranaki town of Opunake. It was the largest in the area for 120 years and  people from Bay of Plenty to Otago reported feeling it.

The quake went largely unreported outside of New Zealand but the Earthquake Commission received almost 1650 claims.

The following NZ volcanoes remain on Alert Level one,  aviation colour code Yellow: Tongariro, White Island and Ruapehu. This morning’s Tokoroa quake was recorded on drums at all three volcanoes.

“Since 1900 there have been 15 M7.5+ earthquakes recorded near New Zealand. Nine of these, and the four largest, occurred along or near the Macquarie Ridge, including the 1989 M8.2 event on the ridge itself, and the 2004 M8.1 event 200 km to the west of the plate boundary, reflecting intraplate deformation. The largest recorded earthquake in New Zealand itself was the 1931 M7.8 Hawke’s Bay earthquake, which killed 256 people. The last M7.5+ earthquake along the Alpine Fault was 170 years ago; studies of the faults’ strain accumulation suggest that similar events are likely to occur again.” USGS