One of the topics I cover in my Physical Geography class at North Idaho College is earthquakes and volcanoes. Some readers have been asking if the recent earthquakes in Ecuador and Japan are a sign of increased activity.
Although, the number of earthquakes this year are considered to be within “normal” ranges, some scientists have expressed concern with the recent cluster. This includes the disastrous 7.8 earthquake in Ecuador and the 7.0 in Japan on April 16, followed by a strong 6.2 aftershock last Wednesday. There have been nearly 700 aftershocks in southern Japan since the big quake on April 16.
According to the USGS, there are an average of 1319 earthquakes worldwide measuring between 5.0 to 5.9. So far, there have been 413 as of late last week. The 6.0 to 6.9 range has about 134 per year. The USGS has reported 41 in across the globe in 2016. Some of these quakes have been reported in Ecuador, Japan, Indonesia and Alaska. On March 12, there was a 6.3 magnitude shaker along Alaska’s Aleutian Chain.
There are approximately 15 massive 7.0 to 7.9 earthquakes each year across the globe. Through April 21, there have been 5, including the massive 7.8 in Ecuador on April 16. So far, in 2015, the USGS has not reported an 8.0 or higher earthquake. The average 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 an amazing 1.5 million each year. Tremors from 2.0 to 2.9 magnitudes are approximately 1.3 million every year.
About 90% of the world’s earthquakes and 75% of the world’s dormant and active volcanoes like in a region that stretches approximately 25,000 miles. This region that 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. As I mentioned several weeks ago, Juan De Fuca plate is diving under the North American plate creating stress that will eventually lead to another large earthquake in the Northwest.
An article from the Express in the United Kingdom says that a seismologist from the University of Colorado says that “current conditions in the Pacific Rim could trigger at least four quakes with a magnitude greater than 8.0.” They also say that “a total of 38 volcanoes are currently erupting around the world, making conditions ripe for seismic activity in the Pacific area.”
Here in the U.S., the coastal areas from California to Alaska receive a number of small earthquakes on a daily basis. However, many say that Oklahoma has now passed up California as the earthquake capital of the U.S. Last year, there were 734 quakes of magnitude 3.0 or higher in Oklahoma. On February 13, there was 5.1 magnitude earthquake which was the third largest to ever hit that state.
Much of earthquake activity is probably related to the activities of the oil and gas industry. Scientists point out the injection of drilling waste of saltwater into the earth comes in contact with the fault lines to produce the earthquakes. There are a number of fault lines in the central portion of the country. The most famous is the New Madrid fault in Missouri which produced 4 major earthquakes in 1811-12. Since that date, there have been thousands of smaller ones in that part of the country.