Digging Deeper Into US Seismic Hazards – Times Standard

Last week’s column raised more questions about seismic hazards. Why is the risk of an earthquake lower in Oregon than in California or Washington and what is the case with all those hotspots in the Midwest and East when most of the continental United States is so far from plate boundaries?

Let’s look at the West Coast first. We are close to the plate boundaries, the San Andreas shift in most of California and the Cascadia subduction zone in northern California to southern Canada. Not surprisingly, our earthquake risk is higher than the rest of the mainland United States. But there is a clear difference between the worlds of San Andreas and Cascadia, and not all portions of the Cascadia margin are uniform.

Offhand, where do you expect more earthquakes – in the diversion of San Andreas or associated with the Cascadia Subduction Zone? If you have a geological separation, you might say subduction zone. Subduction zones are the most seismically active places on the planet, accounting for nearly 70% of earthquakes and more than 90% of the earthquake energy released.

Subduction zones vary greatly in character depending on where they are located, how quickly the sides converge, and how old the fused cortex is. Different sections along the same subduction zone may behave differently. And like all of us, subduction zones also progress and change over time. The modern Cascadia Subduction Zone is but a small remnant of what the boundary once looked like when the Farallon Plate covered most of what we now call the East Pacific.

Seismologists divide the remainder of that subduction zone in the Pacific Northwest into three regions: the portion of the Gorda Plate (or the Gorda Deformation Zone) off the coast of northern California and the far south of Oregon, the Juan de Fuca from Cape Blanco to the Northern State, and the Explorer strip of Island Vancouver to Queen Charlotte Sound. Anyone looking at an earthquake map will notice that these areas behave very differently.

Since 1980, the southern region or Gorda Plate region has produced more than 700 earthquakes of magnitude 4 or greater, including five in the 7th and 12th range. The Explorer Zone is also very active, having recorded nearly 800 earthquakes including 23 in the M6 ​​range. Juan de Fuca is the largest region and between the other two. The number of earthquakes was less than half the number of earthquakes and only one in the M6 ​​range. To further confuse the story, none of the recent Cascadia subduction zone earthquake activity was present on the subduction zone façade. It was the last Beni earthquake more than 300 years ago. The current activity in the Gorda and Explorer regions is due to the fact that these two plates are now so small that they separate. The movement of the large plates around them placed them in a seismic binding. Many scientists argue that the explorer zone is no longer a coherent plate and it is possible that it was not part of the latest Cascadia Subduction Zone earthquake in 1700. The Gorda plate is trending in the same direction and earthquakes as the 1980 M7.2 and 2010 M6. 5 was the result of this disintegration process.

What does the current lack of seismic activity say about the subduction zone? It is closed – this is seismic speech of the two sides tightly stick together and not moving at all. This is not just a guess. We can measure this lockup by what happens to the ground surface above the façade. When subduction pulls the plate below the surface, it causes the Earth to swell and move slightly to the northeast, which can be measured with high-precision GPS instruments.

All of this is taken into account in the US Geological Survey seismic hazard map – the current high level of activity in northern California and in Washington state, British Columbia and the currently closed subduction zone. Northern California and Washington have more frequent earthquakes related to the disintegration of the Gorda and Explorer plates, but we will all be part of the next subduction zone earthquake

For hotspots in southeast Missouri and South Carolina, the seismic hazard in these areas is real and depends on historical earthquakes. Three major earthquakes occurred during a three-month period in 1811 and 1812. There were no seismometers, so an estimate of the magnitude in the upper to intermediate 7 range is based on Al-Felt’s reports. This seismic zone in New Madrid is named after the small town of Missouri near the epicenter of the largest earthquake. An earthquake of equal magnitude is thought to have been near Charleston, South Carolina, in August 1886.

The New Madrid and Charleston earthquakes were natural tectonic events unrelated to human activity. It is very far from modern plate boundaries and Earth scientists have long debated its origins. The explanation that makes the most sense to me is due to plate tectonics – but not tectonics in the modern world. Turn back the clock by 300 million years or so when all the continents were connected in one giant mass called Pangea. The supercontinent held together for more than 100 million years, but it eventually began a long and difficult process of disintegration. Today the African continent gives a glimpse of what could happen. It started to fall apart. There are many fissures in East Africa that will continue to grow over the next tens of millions of years. Ultimately, one continuous fault zone will triumph, forming the edges of a new African Sea.

What happens to old tears that don’t become part of the new board’s boundaries? As the African Sea gets bigger and bigger, they will continue to diverge from each other on their new plate. But, like stretch marks, they will never completely disappear, and are always somewhat weaker than the surrounding rocks and areas where stress builds up. It is plausible that the fault systems of the Midwest and eastern part of the United States are similar features, stretch marks dating back to the birth of the Atlantic Ocean, and more than 100 million years later, are still areas of occasional tectonic activity.

Note: USGS current seismic hazard posted at https://www.usgs.gov/media/images/2018-long-term-national-seismic-hazard-map.

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