Magnitude 5.1 earthquake — Pacific-Antarctic Ridge

A moderate earthquake has struck one of the most isolated spots on Earth this morning, rattling the seabed along the Pacific-Antarctic Ridge far from any human settlement.

The United States Geological Survey recorded the magnitude 5.1 tremor at just after five o'clock this morning, British time. The quake occurred at a depth of 10 kilometres beneath the ocean floor, in waters roughly halfway between New Zealand and the southern tip of South America.

What does magnitude 5.1 actually feel like?

For those of us who've never experienced an earthquake, a magnitude 5.1 is what scientists call "moderate" — strong enough to rattle windows and shake objects off shelves if you're nearby, and certainly enough to wake you up if you're in bed. You'd feel the ground moving beneath your feet, rather like standing on a bus that's braking suddenly, though it would last longer.

The good news is that at this magnitude and depth, and given the location is hundreds of miles from the nearest inhabited land, there's no risk to people or property. The Pacific-Antarctic Ridge is a vast underwater mountain range where two of Earth's tectonic plates are slowly pulling apart, and earthquakes there are relatively common — though rarely noticed by anyone except the monitoring stations.

A very lonely bit of ocean

The coordinates place this morning's tremor in the southeastern Pacific Ocean, in waters so remote that even the hardiest fishing vessels rarely venture there. The nearest land of any significance is several days' sailing away, and the area sits well outside any tsunami risk zones for coastal communities.

These deep ocean ridges are where new seafloor is constantly being born as molten rock wells up from below, cools, and spreads outward. It's a slow, grinding process that occasionally releases tension in the form of earthquakes like this one.

The quake was detected less than an hour ago, and monitoring stations will continue to watch for any aftershocks, though none are expected to pose any concern.

Have you ever felt an earthquake, perhaps while travelling abroad? Or do you remember hearing about tremors in unusual places? We'd love to hear your stories in the comments below.