Seismic stats might rattle your cage

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On Nov. 30, Anchorage, Alaska, was hit with a 7.0 earthquake that led to widespread damage of buildings and roads as well as knocking out power. Fortunately, there were no reported deaths.

Since the big event, there have been over 230 smaller earthquakes measured by the United States Geological Survey.

Alaska holds the record for the strongest earthquake in the United States. It happened on Good Friday, March 28, 1964 at Prince William Sound in Alaska. The massive earthquake had a magnitude of 9.2 and devastated the city of Anchorage and also generated a massive tsunami. The quake was so strong that it was felt as far away as Florida.

The earthquake lasted for approximately 4½ minutes. There were 131 people killed, most of them by tsunamis triggered by underwater landslides rather than by the earthquake-induced tsunami. The tsunami that was generated by the large earthquake had a height of 1,720 feet in Lituya Bay, Alaska.

By the way, the largest earthquake ever to be recorded on this planet was a 9.5 magnitude that occurred on May 22, 1960. It was recorded near Valdivia in southern Chile.

Many people have wondered if a magnitude 10 earthquake is possible. In theory, there is a chance, but it’s very unlikely. Big earthquakes are caused by the sudden slippage of faults, or cracks within the Earth. Their magnitude is partly based on the length of these faults and scientists have not located a fault long enough, in theory, to generate a magnitude 10 earthquake.

Alaska registers more earthquakes per year, about double, than California. Alaska has an average of about 1,000 earthquakes each month.

Now, Oklahoma has passed up California. Much of the earthquake activity in Oklahoma is probably related to the activities of the oil and gas industry. Scientists point out that the injection of drilling waste of saltwater into the earth comes in contact with the fault lines to produce the earthquakes.

For 2018, the number of earthquakes is considered to be within “normal” ranges. According to the USGS, there’s an average of 1,319 earthquakes worldwide measuring 5.0 to 5.9. So far, there have been 1,544 as of late last week. The 6.0 to 6.9 range has about 134 per year. The USGS has reported 109 in 2018 across the globe.

There are approximately 15 massive 7.0 to 7.9 earthquakes each year on our planet. Through Friday, there have been 13, including the Alaska earthquake and a recent 7.5 magnitude near New Caledonia, one of the South Pacific Islands. So far in 2018, the USGS has reported one 8.0 or higher earthquake near Fiji. The global average for an 8.0 magnitude or higher for each year is one.

In terms of the total number of earthquakes starting at a 2.0 magnitude, the USGS estimates that our planet receives nearly 1.5 million each year. Tremors from 2.0 to 2.9 magnitudes are approximately 1.3 million every year.

About 90 percent of the world’s earthquakes and 75 percent of the world’s dormant and active volcanoes live in a region that stretches approximately 25,000 miles. This region looks like a horseshoe, the Pacific “Ring of Fire,” which extends from New Zealand, Indonesia, Japan, southern Alaska and along the U.S., Central American and South American West Coasts.

The Pacific “Ring of Fire” is the result of the movement and collisions of the tectonic plates. The Juan De Fuca plate is diving under the North American plate, creating stress that will eventually lead to another large earthquake in the Northwest.

Back in 1700, an estimated 9.0 earthquake hit the West Coast from British Columbia southward into northern California. Based on geologic evidence, it’s quite possible that this area will be hit again with another strong earthquake within 100 years.

Experts believe that California will be rocked by a massive earthquake by 2037. They believe there is a 99.7 percent chance the Golden State will be hit with a magnitude of 6.7 or higher within the next 30 years.

Here in Idaho, on April 23, 2015, a series of small earthquakes shook the Sandpoint area that were also felt in Coeur d’Alene and other areas. The following morning, April 24, a 6.1 quake was reported off the coast of British Columbia. It seemed to be very seismically active for the Northwest around that time.

In terms of our local weather, we will be in a “rain and snow” pattern through at least the end of the month. Cliff and I still believe there is a good chance that we’ll have a white Christmas, assuming that one of those storms near Christmas Day isn’t too warm and produces more rain than snow.

But, for you who love the snow, enjoy it while you can. Ocean waters are still warming up and a new El Nino is expected to be declared at any time. During El Nino years, we often see our heaviest snowfalls in December. As we move into January, February and March, snowfall totals usually are below normal levels. Stay tuned.

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Contact Randy Mann at randy@longrangeweather.com

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