Some of the largest earthquakes and tsunamis in the world originate from the Cascadia Subduction Zone, stretching 1,127 kilometers from Northern California to British Columbia.
In the Cascadia Subduction Zone, the Pacific Ocean floor sinks beneath North America. When the fault accumulates and periodically releases stress, it can trigger mega-earthquakes and record-breaking tsunamis, according to a study published in the journal Science Advances.
Location of the Cascadia Subduction Zone. (Photo: IAS Gyan).
Mega-earthquakes are the strongest type of earthquakes on Earth and arise from subduction zones, where one tectonic plate slides beneath another. As the rock at the edge of the tectonic plate is compressed and bent, it accumulates elastic energy. When the energy builds up too much, it is released suddenly as the tectonic plate slips along the fault line.
During this slip, the tectonic plate transmits massive amounts of energy into the surrounding seawater. This energy causes the sea water to move and rise above normal water levels at the surface. The mass of water then crashes back down under the force of gravity, causing the energy to spread out horizontally in the form of a tsunami. The wave can travel at speeds of over 840 km/h. If it is in the open ocean, it may dissipate, but if it is near the shore, it can be extremely dangerous. This is because, in shallow waters, where energy is compressed, the tsunami moves slowly but can rise much higher, sometimes reaching up to 30.5 meters. Upon reaching land, it can flatten buildings inland. Debris and any victims caught in the wave are at risk of being washed away as the water recedes.
The destructive power of the Cascadia Subduction Zone makes it a significant concern for scientists. For tsunamis, early detection of disasters is the best way to prevent damage. In an effort to create a better warning system for the Cascadia Subduction Zone, the new research utilizes advanced geophysical equipment to provide the first comprehensive survey of the area.
According to lead researcher Suzanne Carbotte, a marine geophysicist at the Lamont-Doherty Earth Observatory of Columbia University, one of the key findings revolves around the discreteness of the fault, which includes at least four segments. This can help experts better understand past events, including the magnitude 9 mega-earthquake that occurred in January 1700, which generated a tsunami that reached as far as Japan. The 1700 mega-earthquake is one of the largest earthquakes in North American history. According to the Cascadian Region Earthquake Workgroup (CREW), available evidence suggests that such events occur approximately every 500 to 600 years, but they could happen more frequently, with a recurrence interval of 100 to 300 years, meaning that all residents in the Cascadia region need to be prepared for major earthquakes in their lifetime.
The research team hopes that understanding the risks of mega-earthquakes and tsunamis from the Cascadia Subduction Zone will help people gain a better understanding of this complex geological feature of North America and prepare more effectively for future natural disasters.
