Recent Earthquakes not Unusual for Eastern Bay

The number of recent earthquakes in the Eastern Bay of Plenty is not unusual, but Earth Sciences New Zealand said it serves as a reminder to think about what to do in bigger events.

Since mid February, Edgecumbe has been rocked by a number of earthquakes, the largest of which was a magnitude for on March 1st. 

Earth Sciences New Zealand Seismic Officer Katie Jacobs said "The Eastern Bay of Plenty is a really common area for earthquakes in general and I'm sure people who live there are no stranger to feeling them, but can always be a bit unnerving when they come close together in time."

The earthquakes abruptly stopped after the week of March.

"That's not uncommon for it to kind of start and stop, but that could be the end of the sequence. It's hard to know what will come next," Jacobs said.

The pattern seen in Edgecumbe over the past month is not usual either she said.

Earthquakes typically "cluster in time" creating earthquake sequences. 

The most common sequence is the main shock aftershock sequence, but a less common sequence is a number of smaller earthquakes called an "earthquake swarm." 

"And that's probably what's happening here, some kind of earthquake swarm," which could have a number of causes Jacobs said. 

Fluid movements in the Earths' crust and connection to the Taupō volcanic zone could be the cause but, she said the earthquake activity is "not necessarily directly volcanic related."

Most likely it is "a lot of different things in addition to normal faulting processes happening in the area."

There is currently no direct connection between the activity around Edgecumbe and Whakaari White Island. 

"But obviously, people will be able to see that Whakaari is continuing to steam," she said. 

Whakaari White Island was upgraded to an alert level three and aviation colour code orange yesterday afternoon. 

Since February last year, more than 500 earthquakes over magnitude three were reported in the Eastern Bay of Plenty. 

The size and number of earthquakes recently are not a cause for concern, Jacobs explained. 

Only thrirty-three earthquakes over magnitude three have been reported in the last month, which standard she said. 

"I wouldn't say this is a particularly large sequence for the area, or a large swarm."

"There have been test sequences that have gone on for weeks or months or had larger earthquakes around magnitude 4 and larger," she said. 

However, these smaller earthquakes serve as a good reminder to think about larger events. 

"Feeling a shake is always a good opportunity to check in on your own earthquake preparedness and plans for larger events."

"Not in an anxious way, but checking in that you do have a plan or thinking about how things might go," she said. 

Checking in with whanau, neighbours and the community about earthquake preparedness is important to ensure everyone knows what to do in larger events.