Several major earthquakes have struck around the Pacific Ring of Fire over the past week, causing widespread damage in Japan, Ecuador and Tonga.
They are the latest in a number of devastating earthquakes around the edges of the Pacific Ocean over the past few years.
What is the Pacific Ring of Fire?
What caused the recent quakes?
Are earthquakes increasing?
Geonet seismologist Dr John Ristau says earthquakes are not getting worse.
"The actual global average of earthquakes of these magnitudes hasn't changed since we've been keeping track of them," he says.
"Population increase means more people live in earthquake-prone areas, therefore more people get affected."
He points to a magnitude 7.8 earthquake in the sparsely populated Dusky Sound, Fiordland in July 2009, which received little attention.
The seismic activity around Vanuatu and Tonga is not that unusual, Dr Ristau says. It's a very active area, and to get a 5.5 or 6 magnitude quakes is fairly normal.
Are the Japan and Ecuador quakes related?
Dr Ristau says it’s highly unlikely that earthquakes on the opposite side of the ocean are related. But earthquakes can affect other areas nearby.
"The earthquake in Ecuador will have changed stress conditions to the north and south, for example, making it more likely that there could be a major quake in the nearby area.
"One thing we do know is the large ones can trigger small ones at a great distance. We did find in 2010 an 8.8 off Chile -- the seismic waves triggered some small quakes in NZ."
He says the measurements do not give scientists an ability to predict quakes, but they can map out areas near an epicentre where there are increases or decreases in stress on fault lines.