One of the most dangerous places on the planet is prone to devastating earthquakes and tsunamis. Large earthquakes are said to occur in Cascadia approximately every 300 to 500 years. The last time it happened was in 1700.
A research vessel from a Columbia University project has conducted a comprehensive study of the complex structures found on the seabed of an area considered one of the world’s greatest geological hazards.
Off the Pacific coast of North America, there is a nearly 1,000-kilometer-long stretch where the ocean floor slowly sinks beneath the continent. This location, known as the Cascadia subduction zone, is a megathrust fault where tectonic plates slide against each other. This movement creates enormous tension that is eventually released and causes the world’s largest earthquakes.
This type of event was responsible for the Fukushima nuclear disaster in 2011. Similar areas exist in Alaska, Chile, and New Zealand, among other places.
A research vessel carried a range of state-of-the-art geophysical equipment across nearly the entire region on a 41-day voyage. The data collected allowed researchers to determine the shape of the subducting oceanic plate, sediments, and the composition of the upper part of the North American plate.
The study found that the megathrust has a more complex geometry than previously assumed. The new framework will enable a better assessment of earthquake and tsunami hazards.
The researchers focused on a specific section of the large rift, which extends from southern Vancouver Island through Washington state and ends roughly at the border with Oregon. They found that the low subduction angle means it is likely to amplify any onshore earthquakes.
The study was published in the journal Science Advances. Scientists emphasize that earthquakes cannot be predicted, but understanding the underground structure and mechanics of the Cascadia subduction zone will allow them to determine where earthquakes are most likely to occur, their magnitude, and the warning signs they may cause.