·

Slow-slip event detected off the coast of Gisborne, New Zealand

slow-slip-event-new-zealand-april-2019

GNS scientists are monitoring a slow-slip event that started at the end of March 2019 near Gisborne, off the east coast of North Island, New Zealand. Slow-slip events are linked to an increase in localized earthquake activity. A similar sequence of earthquakes was observed during the March 2010 Gisborne slow-slip event.

Slow-slip events are quite common in this part of New Zealand, due to the subducting Pacific Plate moving westward under the Australian Plate, GNS Science Geophysicist Laura Wallace said April 5.

Slow-slip events in this area tend to last around a few weeks, so this one is still in its early days, she said.

Scientists have so far recorded up to 3 cm (1.18 inches) of eastward displacement at GeoNet continuous GPS sites. This is caused by up to 10 – 15 cm (4 – 5.9 inches) of movement on the Hikurangi plate boundary offshore of Gisborne, as you can see from the below model.

Slow-slip movement model showing the direction of movement of GeoNet GPS sites and amount of displacement at the plate boundary. Credit: GNS Science

"Our scientists have been anticipating this slow-slip event, as our slow-slip record has shown regular events every 1 – 2 years, and much larger events every 4 – 6 years," Wallace said. This event is on track to be as large as the biggest previous slow-slip event we recorded off Gisborne in March 2010.

"Because we know that this area has regular slow-slip events, our scientists have been studying this area for years. Right now, we have instruments out in on the seafloor off Poverty Bay that are waiting to capture the data from events like this. Our scientists can then study these land movements and changes offshore, to better understand the processes at subduction zones and the relationship of slow slip events to earthquakes.

"Slow-slip events are linked to an increase in localized earthquake activity, which we are seeing off the coast of Mahia Peninsula. Most of these quakes have been too small to feel."

Earthquakes detected from April 1 to 5, 2019. Credit: GNS Science

GNS has recorded dozens of slow-slip events since their first detection in 2002 after installing a GPS (Global Positioning System) network around New Zealand to monitor land movement.

Slow-slip events (sometimes called silent earthquakes) are undetectable by both humans and seismograph network because they move faults over weeks to months instead of within seconds like the earthquakes that you typically think of.

Featured image credit: GNS Science

If you value what we do here, open your ad-free account and support our journalism.

Share:

Related articles

Producing content you read on this website takes a lot of time, effort, and hard work. If you value what we do here, select the level of your support and register your account.

Your support makes this project fully self-sustainable and keeps us independent and focused on the content we love to create and share.

All our supporters can browse the website without ads, allowing much faster speeds and a clean interface. Your comments will be instantly approved and you’ll have a direct line of communication with us from within your account dashboard. You can suggest new features and apps and you’ll be able to use them before they go live.

You can choose the level of your support.

Stay kind, vigilant and ready!

$5 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$50 /year

$10 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$100 /year

$25 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$200 /year

You can also support us by sending us a one-off payment using PayPal:

Leave a reply

Your email address will not be published.