“Massive Quakes Hit Bay Of Plenty”

The Trademe board was buzzing in the early hours of this morning with posters scared stiff about a prolonged swarm of shallow earthquakes that were hitting Whakatane and the Bay of Plenty overnight,  it shows how frightening and disruptive shallow quakes can be for those near the epicentre:

“Massive Quakes Hit Bay Of Plenty”

3:56am ” Been a rough night here for Whakatane…..had 3 massive quakes inside 2hours…..was a couple….real real huge shakes!!!….was felt in Whakatane, Rotorua, Ohope….
4.3 20km north of Whakatane 5km deep….2:38am
3.2 20km North of Whakatane 5km deep….2:48am
and another one at 3:30am…still to be scaled….”

3.59am “4.0 10kms north of Whakatane at 5km deep 3:42am”

4.03am “gonna go watch a movie to settle my nerves lol…there was also 8 recorded over the weekend in Whakatane….so something is starting to happen”

4.22am “4:21am….another quake”

4.33am “3.7 20kms north of whakatane 5kms deep 4;21am Poor people in Matata getting rocked by all this…”

5.04am “2 more quakes 5:01 and 5:03 but i think they’d be classfied as 1 quake not 2…”

5.17am “damn this recent one…had NO depth at all. 10km north east of Edgecumbe….3.7 and NO depth…5:03am

6.24am “massive for those who are sleeping right on top of the epicentres..i’m 20ks away and it scared the shit outta me, so what about those right on top of it”

6.31am “3.5 6:18am 10kms north of whakatane”

some reponses to him:

• “they have been very much felt, i have felt 3 the noise wakes then it shakes i run out of bed thinking its never going to end its going to be big, then it stops lol but there have been so many hopefully it sorts it self out.”

• “What a crap nights sleep… the first one I actually bolted out of bed to get the kids but then it stopped. Just as I would fall asleep, then another one would hit. First time in years I’ve had my son sleep in my bed!” 

It was the second cluster to hit the region this week and unsettle residents in the area. The Whakatane Beacon reported on 18 May :

“Swarm of earthquakes hit the Bay”
“THE Eastern Bay was hit by a swarm of earthquakes over the weekend.
The first was a 2.5 magnitude quake at 9.09pm on Saturday, 10 kilometres north of Whakatane with a shallow focal depth of 2.5km.
This was followed 30 minutes later by a larger 3.5 quake, also 10km north of Whakatane with a focal depth of 5km.
At 10.01pm and 10.36pm there were two 3.1 quakes, both 10km north of Whakatane and 5km deep.
The final shake of the evening had a magnitude of 2.9km and a very shallow depth of 1km. It was similarly centred 10km north of Whakatane. Then at 2.07am on Sunday there was a sixth quake of 3.3, 20km north of Whakatane. It had a depth of 5km.
Further away a 4.5 quake was recorded north-east of Matawai at 10.50am Sunday, with a focal depth of 5km. “

In 1931 a magnitude 7.8 quake devastated the Hawke’s Bay region. It was centred 15 km north of  Napier and it lasted for two and a half minutes.

There were 525 aftershocks recorded in the following two weeks. The main shock could be felt in much of the lower half of the North Island. (source)

In August 2006 experts at the Natural Hazards Management Conference in Christchurch warned that Rotorua, Taupo and Whakatane are set to be wiped out in a massive, long overdue earthquake and that people should be prepared for a catastrophic event:

“Geology experts Tim Davies and Mauri McSaveney have predicted that an alpine fault earthquake is overdue, and would result in the East Cape ripping away from New Zealand, destroying the plateau that Rotorua is based on and taking Taupo and Whakatane with it.
The pair say the earthquake will strike “out of the blue” and cause widespread death, shut down power generators, create tsunamis within New Zealand and overwhelm emergency services.
“The most likely time [for the quake] is now. The next most likely time for it to happen is tomorrow,” Associate Professor Davies, of Canterbury University, told the conference.
“It will occur with no recognisable warning. We can’t manage it – we have to adapt to it.”
The pair have outlined a nightmarish scenario in the aftermath of the quake and are urging people to be prepared as best they can. Overseas help would be needed when the quake struck…
The interval since the last event (in 1717) is longer than any interval between known earlier events.

Rotorua historian Don Stafford said the experts’ predictions were probably right and residents should be prepared.
“Who else could you listen to other than an expert. They have their reasons for why they believe they are worth listening to.”
Mr Stafford said historically there had been major eruptions and earthquakes in the Central North Island, with the most recent being Mt Tarawera in 1886.
“Lake Rotorua was a gigantic eruption 230,000 years ago. There have been gigantic eruptions for thousands of years.
“The historic massive eruption of Lake Taupo was recorded in China, Rome and Italy.”
Mr Stafford said the Central North Island had been relatively quiet during the past few decades.
“We have had it pretty sweet and I don’t doubt for one minute that there will be more big eruptions. … We would be foolish to presume that it won’t happen just because we are living here.”

Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8.

These occurred in approximately 1100, 1450, 1620 and 1717 AD, at intervals between 100 and 350 years. The 1717 quake appears to have involved a rupture along nearly 400 km of the southern two thirds of the fault.  

Scientists say that a similar earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. (source)


Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault.
A list of  30 most recent earthquakes in New Zealand may be found here.

Also See blog : “Mass aircraft grounding possible in NZ too, scientists say”

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