Landslides can be seen on the crater rim of Blue Lake on Raoul Island in the Kermadec Islands. Photo / GNS Science
Landslides can be seen on the crater rim of Blue Lake on Raoul Island in the Kermadec Islands. Photo / GNS Science
They were the earthquakes that resulted in tsunami warnings and mass evacuations for those living on coastal areas around the country.
But it seems the quakes that struck in the early hours three weeks ago - on Friday, March 5 - also resulted in a different kind of natural phenomena.
More than 300 landslides have been found on Raoul Island, in the Kermadec Islands, near where an 8.1 magnitude quake struck that morning.
That big shake came after a 7.1 magnitude quake off the North Island about 2.30 that morning, followed by a 7.4 magnitude quake just over four hours later.
GeoNet, a collaboration between the Earthquake Commission and GNS Science, has revealed stunning images showing just how much the island had changed after staff visited the area after the quakes.
Following the March 5 M8.1 earthquake, 80km from Raoul Island, our team of experts discovered that the island was scattered with more than 300 new landslides. Read all about them here: https://t.co/PigtATl0ci#eqnzpic.twitter.com/pxyYMSIJEp
"Our team of experts discovered that the island was scattered with more than 300 new landslides."
With the help of the NZ Defence Force, staff members were able to map out the various landslides using satellite imagery, oblique photographs and pre-earthquake imagery.
"The coastal slopes generally have a high stimulated landslide portability and most of the mapped landslides occurred on these slopes," a statement said.
"This is because they are generally steeper in angle and higher in local slope relief."
Staff also found that larger landslides had happened on the volcanic crater rim; which corresponded to areas of "high simulated landslide probability".
Landslides like two rugby fields neck-deep in rocks
Landslides on the coast and rockfalls near Ngaio Bluff. In the background is Blue lake. Photo / GNS Science
GNS Science geologists Chris Massey, Brenda Rosser and Biljana Lukovic said the "most spectacular" landslides happened around Blue Lake and along the rugged coastline on the island.
Some of the larger ones identified were up to about 20,000 m3.
"Think two rugby fields neck-deep in rocks," they said.
The other relatively smaller landslides were about 100m3 to 200m3 and most were made up of rock and soil avalanches and falls.
"There was a significant slip at Bells Beach - where about 400m of coastal cliffs collapsed, leaving a plume of sediment in the ocean."
The major quakes earlier this month were described as a "swarm" and resulted in much of the North Island - including Northland, parts of the Bay of Plenty and the East Coast - being affected by a tsunami warning.
Many towns were also evacuated and the National Emergency Management Agency issued a series of warnings that day.
