Was the 1700 Cascadia earthquake part of a series of earthquakes?

The famous Cascadia earthquake of 1700 that changed the western coast of North America and sent a tsunami across the Pacific to Japan may have been one of a series of earthquakes, according to new research presented at the American Seismological Association (SSA) 2021 Annual Meeting.

Evidence from coasts, tree rings, and historical documents confirm that a massive earthquake occurred in the American Cascadia Subduction Zone on January 26, 1700. The prevailing hypothesis is that a single large earthquake with a magnitude of 8.7 to 9.2 encompassing the entire tectonic plate boundary was responsible for the effects recorded on Both sides of the Pacific Ocean.

But after simulating more than 30,000 earthquake ruptures within this magnitude using software that designs the three-dimensional tectonic engineering of the region, Diego Melgar, president of the Ann and Lou Williams School of Geosciences at the University of Oregon, concluded that those same effects could be produced by a series of earthquakes.

Melgar’s analysis indicates that the partial rupture of at least 40% of the gigantic boundaries in an earthquake of 8.7 magnitude or greater could explain some coastal subsidence in North America and the Japan tsunami of January 26, 1700. But there could also have been as many as Four other earthquakes, each of magnitude 8 or less, could have produced the rest of the subsidence without causing a tsunami large enough to be recorded in Japan.

His findings do not exclude the possibility that the 1700 Cascadia earthquake was a stand-alone event, but “the event of January 26, 1700, as part of a long-lived series of earthquakes potentially spanning many decades, should be considered as the hypothesis that is likely to be equal to the least “.

Knowing whether a 1,700 earthquake is in a sequence has implications for how earthquake risk maps are generated in the area. For example, the US Geological Survey risk map calculations are based on the Cascadia Fracture Zone being completely ruptured about half the time and partially rupturing the other half of the time, Melgar noted.

“But are we really sure that this is true, or maybe it is time to reconsider the matter?” Melgar said. “Whether it’s a partial or complete rupture that’s basically driving everything we put on the risk maps, so we really need to work on that.”

Since the first analyzes of the 1700 earthquake, there has been more data from the field, repeated earthquakes modeling of the Cascadia subduction zone and a better understanding of the physics of mega earthquakes – all of which allowed Melgar to reconsider the possibilities behind the 1,700 earthquakes. Researchers have also written code for years now to simulate earthquakes and tsunamis in the region, in part to inform earthquake early warning systems like ShakeAlert.

If there is a series of earthquakes instead of one, Melgar said, that might help explain why there is so little good geological evidence for the 1,700 event in places like the Olympic Mountains in Washington state and southern Oregon.

However, he noted that these specific areas are difficult to work in, and “may not necessarily be good records of the geological signals that paleontologists are looking for.”

Melgar’s models show that even the smaller Cascadia earthquake could trigger a tsunami with enough force to reach Japan. He warned that these small earthquakes could pose a major tsunami hazard to North America as well. “It might be less catastrophic, because it doesn’t affect such a large area because the rupture is more compact, but we’re still talking about a massive tsunami.”

He suggested that it might be useful to revisit and re-run the old-fashioned analyzes of the 1700 event, to get a clearer picture of how it fits into the overall history of earthquakes in the region.

“Cascadia records earthquake geology a lot better than many other parts of the world, so I think just going back with modern methods is likely to yield a lot of new results,” Melgar said.

###

Disclaimer: AAAS and EurekAlert! Is not responsible for the accuracy of the newsletters sent to EurekAlert! Through contributing institutions or to use any information through the EurekAlert system.

.

What Are The Main Benefits Of Comparing Car Insurance Quotes Online

LOS ANGELES, CA / ACCESSWIRE / June 24, 2020, / Compare-autoinsurance.Org has launched a new blog post that presents the main benefits of comparing multiple car insurance quotes. For more info and free online quotes, please visit https://compare-autoinsurance.Org/the-advantages-of-comparing-prices-with-car-insurance-quotes-online/ The modern society has numerous technological advantages. One important advantage is the speed at which information is sent and received. With the help of the internet, the shopping habits of many persons have drastically changed. The car insurance industry hasn't remained untouched by these changes. On the internet, drivers can compare insurance prices and find out which sellers have the best offers. View photos The advantages of comparing online car insurance quotes are the following: Online quotes can be obtained from anywhere and at any time. Unlike physical insurance agencies, websites don't have a specific schedule and they are available at any time. Drivers that have busy working schedules, can compare quotes from anywhere and at any time, even at midnight. Multiple choices. Almost all insurance providers, no matter if they are well-known brands or just local insurers, have an online presence. Online quotes will allow policyholders the chance to discover multiple insurance companies and check their prices. Drivers are no longer required to get quotes from just a few known insurance companies. Also, local and regional insurers can provide lower insurance rates for the same services. Accurate insurance estimates. Online quotes can only be accurate if the customers provide accurate and real info about their car models and driving history. Lying about past driving incidents can make the price estimates to be lower, but when dealing with an insurance company lying to them is useless. Usually, insurance companies will do research about a potential customer before granting him coverage. Online quotes can be sorted easily. Although drivers are recommended to not choose a policy just based on its price, drivers can easily sort quotes by insurance price. Using brokerage websites will allow drivers to get quotes from multiple insurers, thus making the comparison faster and easier. For additional info, money-saving tips, and free car insurance quotes, visit https://compare-autoinsurance.Org/ Compare-autoinsurance.Org is an online provider of life, home, health, and auto insurance quotes. This website is unique because it does not simply stick to one kind of insurance provider, but brings the clients the best deals from many different online insurance carriers. In this way, clients have access to offers from multiple carriers all in one place: this website. On this site, customers have access to quotes for insurance plans from various agencies, such as local or nationwide agencies, brand names insurance companies, etc. "Online quotes can easily help drivers obtain better car insurance deals. All they have to do is to complete an online form with accurate and real info, then compare prices", said Russell Rabichev, Marketing Director of Internet Marketing Company. CONTACT: Company Name: Internet Marketing CompanyPerson for contact Name: Gurgu CPhone Number: (818) 359-3898Email: [email protected]: https://compare-autoinsurance.Org/ SOURCE: Compare-autoinsurance.Org View source version on accesswire.Com:https://www.Accesswire.Com/595055/What-Are-The-Main-Benefits-Of-Comparing-Car-Insurance-Quotes-Online View photos