Heightened earthquake activity off Vancouver Island points to deep sea eruption, scientists say

Scientists say we’re due for a deep sea eruption sometime in the near future after heightened earthquake activity has been noted off the coast of Vancouver Island.

Ocean Network Canada (ONC) says that a peak of more than 200 earthquakes per hour were detected on March 6, 2024 at a deep sea site within their observatory.

The organization says that is the highest rate of earthquakes observed in the region since 2005.

One of the earthquakes detected was about 4.1 magnitude quake at the NEPTUNE observatory’s Endeavour site, at a depth of about 5 kilometres and 240 kilometres offshore of Vancouver Island.

ONC explains that they’ve been seeing Increased earthquake rates at the site since 2018, with the March 6 peak swarm following several days of increased small earthquake frequency.

According to Zoe Krauss, a marine seismology PhD candidate at the University of Washington, the spike in activity at the Endeavour segment of the Juan de Fuca Ridge could be a sign of an “impending magmatic rupture,” which is a natural phenomena that can form new ocean floor.

“As tectonic plates pull apart, cracks form on the seafloor and are filled periodically by 800 degree celcius magma rising from deep beneath the Earth’s crust,” says ONC.

“The intense heat from the magma cools rapidly once in contact with the cold seawater and solidifies into new oceanic crust. This cyclic process occurs in bursts, and at Endeavour, researchers expect this event to happen roughly every 20 years.”

That might sound alarming, however ONC says there is no cause for concern.

”No one should be alarmed about this great swarm of earthquakes. They are far offshore and cause no danger. Rather, the data are exciting to the science community and certainly not menacing,” says Kate Moran, ONC President and CEO.

“We can use earthquake activity to track the level of built-up stress at the Endeavour segment in real-time using seismic data provided by Ocean Networks Canada. More earthquakes mean more stress build-up,” adds Krauss.

“The NEPTUNE observatory dataset has allowed us to observe significant increases in earthquake rates over the last few years.”

The observatory will allow researchers to monitor and record data from the rupture of the Endeavour segment in near real-time.

“Having a whole suite of instrumentation as opposed to just seismometers allows us to immediately see what else was going on, like temperature changes inside a black smoker, or instruments starting to tilt, or listen via hydrophones if there was any hissing or tumbling from lava breaching the seafloor should that happen,” says Martin Scherwath, ONC senior scientist.

ONC says that observation of the last known rupture event in 2005 relied on battery-powered autonomous seafloor seismometers.

This summer, ONC will be partnering with Ocean Exploration Trust to do maintenance on the offshore NEPTUNE observatory, providing an opportunity to observe the impact of this tectonic event on the seafloor and nearby hydrothermal vents.