Thursday, December 7, 2023


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Revolutionizing Seismic Research in the Cascadia Region

A view of the Seattle’s Space Needle and surrounding area with a bay in the background

A research center will be established to study the Cascadia Subduction Zone, a geological area stretching from Northern California to British Columbia, Canada, along the west coast of North America. This zone has the potential to produce significant earthquakes, but its seismic risks are not fully comprehended. The center aims to enhance preparedness for this region.

CRESCENT, the Cascadia Region Earthquake Science Center, has received a $15 million grant from the U.S. National Science Foundation (NSF) and will involve researchers from 14 American institutions.

According to Ruth Harris, a senior scientist at the U.S. Geological Survey’s Earthquake Science Center, the new center is highly stimulating. Harris, who is not part of the project, emphasized the significance of focusing on Cascadia due to its high potential for earthquakes.

Gaining a Deeper Insight into Subduction Zones

A sign reading “tsunami evacuation route” stands before a background of shrubs and cloudy sky.

A marker directs people along a designated pathway for escaping a tsunami on the shoreline of Washington State. Seismic activity in the Cascadia Subduction Zone may result in tsunamis affecting British Columbia, Oregon, Washington, and other areas. Attribution: xtinarson, Pixabay.

The Cascadia Subduction Zone is a boundary between tectonic plates, stretching 1,100 kilometers (700 miles) and separating North America from the Juan de Fuca plate which is subducting. The main fault in this area is known as a megathrust and it moves eastward under the coast and major cities like Seattle and Vancouver, B.C. There are also smaller faults present in Cascadia that can cause significant hazards. While the megathrust experiences regular movement, there has not been a major earthquake since 1700 with an estimated magnitude of 9.0, which also resulted in tsunami waves reaching the Pacific.

Diego Melgar, a seismologist at the University of Oregon and principal investigator for CRESCENT, stated that despite the danger, earthquake readiness in the Pacific Northwest is falling behind.

Not until the 1990s did we come to the realization that it still has the ability to produce major earthquakes.

In contrast to California, where the occurrence of frequent moderate earthquakes has motivated residents and policymakers to take action, major earthquakes are not common in the Pacific Northwest. Therefore, the potential for seismic activity went unnoticed for many years. Geophysicist Melgar states that scientists previously believed the Cascadia subduction zone to be inactive, but it was not until the 1990s that it was recognized as still capable of producing significant earthquakes.

Harold Tobin, a professor at the University of Washington and director of the Pacific Northwest Seismic Network (PNSN), stated that while researchers have made advancements in recent decades, there is still a need for further investigation. In particular, there has been a significant emphasis on studying earthquakes along transform faults like the San Andreas Fault in the U.S., but less is known about subduction zones. Tobin emphasized the importance of increasing our knowledge of subduction zones to match that of transform faults.

The goal of CRESCENT is to unite earthquake researchers in Cascadia and fill in the missing pieces.

The main objective of the center is to develop a community-approved model of the faults in the area. According to Melgar, there are numerous crustal faults that are not well understood. To achieve this goal, CRESCENT scientists will utilize information from the PNSN, on-site observations, experiments, and computational modeling to gain a better understanding of the faults’ location and 3D structure.

The town square can be called CRESCENT.

An unresolved matter is how much friction acts as a barrier in the subduction zone, inhibiting movement. Strain builds up in locked plates and is eventually released in the form of earthquakes. If the frictional locking is strong, it can result in powerful earthquakes. The locked subduction zone off the coast of Japan has caused numerous major earthquakes in recent times, such as the 9.0 magnitude Tōhoku earthquake in 2011.

Many experts have reached a consensus that a portion of the Cascadia Subduction Zone is highly constrained, but the specific areas of constraint and continuous movement are not well understood. This presents challenges for seismologists attempting to predict earthquake and tsunami risks.

According to Melgar, CRESCENT could serve as a central gathering place for discussing and resolving problems. Through its research, the center aims to evaluate the potential risks of earthquakes, tsunamis, and landslides that may pose a threat to communities in Cascadia.

Transforming scientific information into educated decisions.

CRESCENT aims to not only aid in research, but also promote collaboration between scientists, policymakers, local communities, and private industry. Tobin emphasized the importance of ensuring practical use and informed decision-making from the scientific findings at every level.

CRESCENT is an “exciting opportunity,” said Tim Dawson, manager of the Seismic Hazards Program at the California Geological Survey, who is not involved with CRESCENT. “The multidisciplinary approach. . .will lead to new insights into the workings of subduction zones with practical applications for public safety, building more resilient communities, and developing the next generation of earthquake scientists.”

—Caroline Hasler (@carbonbasedcary), Science Writer

Reference: Hasler, C. (2023), Revolutionizing earthquake research in the Cascadia region, Eos, 104, Published on October 16, 2023.

Text © 2023. The authors. CC BY-NC-ND 3.0

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