Unusual seismic activity in Canada suggests deep-sea magmatic rift

For residents of Vancouver Island, Canada, the earthquakes do not pose a threat because they are low intensity and located in a place called Endeavor, about 240 kilometers from the coast, explains Zoe Krauss, a doctoral student in marine geophysics. from the University of Washington. , in an article published by Live Science on Thursday, March 21.

This area is home to a large number of hydrothermal vents and is located in the Juan de Fuca Mountain Range, where the seabed extends. This location must be distinguished from the subduction zone, which is a region where one tectonic plate sinks beneath another plate in the mantle. Closer to the coast, it can cause destructive earthquakes.

A new oceanic crust

Recently, seismic activity described as unusual was observed at the Endeavor site, permanently monitored as part of experiments managed by Ocean Networks Canada. Although the region has become more active since 2018, specialists were surprised to witness a real outbreak: on March 6, 1,850 earthquakes were recorded, with an average of 200 per hour, which shook the seabed.

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California: the main earthquakes of the last 30 years

This situation could be a sign that a new oceanic crust is about to be born through a magmatic rupture in the open sea. “The vast majority (tremors) is less than magnitude 1. These are these little ‘pops’ (WHO) “It allows you to track where things happen, where they break, and where they move.”continues the doctoral student.

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A phenomenon that occurs every twenty years

Despite this surprising situation, researchers do not seem to show any concern. “This is not going to cause a ‘major catastrophe’ in the subduction zone”, Zoe Krauss explains to LiveScience. Before pointing out that earthquakes are scientifically interesting because they can reveal details about how the ocean floor breaks up and new crusts form. At the Endeavor site, the Pacific Plate and the Juan de Fuca Plate are moving apart. This stretching creates long linear faults and thins the crust, allowing magma to rise. Once the magma reaches the surface, it cools and hardens, forming new oceanic crust.

How can we explain these recent earthquakes? The specialist in marine geophysics considers it likely that the seabed was stretched to the maximum, a situation that would have caused it to accumulate a lot of “stress.” At the Endeavor site, this phenomenon occurs when the plates move about 1 m apart. Over time, the restriction will be removed as the magma rises toward the thinned crust and cools.

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This event generally occurs every two decades. The region was last shaken by an earthquake in 2005… Deadlines were respected. Because constant monitoring of the Endeavor site began in 2011, the team does not have enough hindsight to know whether a magmatic intrusion like this has occurred before. Many questions – “How is the Earth’s crust formed? Why do these events occur there? What triggers them?…” – remain unresolved.

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