Sunday, September 10, 2017

210 earthquakes detected in Idaho, experts say M7.0 possible but not likely

A total of 210 earthquakes have been detected in Southeast Idaho near the city of Soda Springs, Caribou County since Saturday, September 2, 2017. Experts say that they can't guarantee there won't be a larger quake in this area, but 'the possibility is extremely low.'
The U.S. Geological Survey registered a total of 210 earthquakes between 23:26 UTC on September 2 and 12:18 UTC on September 9, including M5.3 at a depth of 6.5 km (4 miles), the strongest so far. Magnitudes ranged from 1.6 to M5.3 at depths between 0.6 to 12.9 km (0.4 to 8 miles).
Earthquake swarm near Soda Springs, Idaho September 2 - 9, 2017 - map
Earthquakes detected near Soda Springs, Idaho since September 2, 2017. Credit: USGS
According to experts, there is a possibility a M7.0 could strike somewhere in this area, but the possibility of that happening is extremely low. If a destructive M7.0 earthquake did occur, it could happen in the region shaken by the current swarm or it could happen elsewhere in the region where faults also exist.
"While we can’t guarantee that there won’t be a larger quake in this area, the possibility is extremely low," said Shannon Kobs Nawotniak, an Idaho State University geosciences assistant professor who studies earthquakes, as quoted by the Idaho State Journal.
"We live in a seismically active area, so everyone should always be up to date on their earthquake safety, just like they would for a fire drill. It is prudent to be prepared, even when the likelihood of the event is very low."
Dr. David Pearson, an Idaho State University geologist who studies earthquakes, said for ISJ that other locations where the 7.0 quake could happen include Fremont, Teton, Oneida, Franklin and Bear Lake counties, southeast Bannock County and eastern Bonneville County.
Pearson said the chance of the 7.0 quake occurring are very low but considering the current earthquake swarm that's shaking Southeast Idaho people should be prepared for it nonetheless.
"There is most likely not going to be a larger earthquake but there is the possibility of a larger one," Pearson said. "I don’t want to say everything is fine here because there’s the possibility it won’t be."
Pearson advised Southeast Idahoans to make sure they secure all heavy objects in their houses to walls to keep them from falling. He also said it would be wise to remove anything heavy that’s above your bed so it can’t fall on you and cause injury.
The strongest earthquake in the history of Idaho is M6.9 that struck in 1983 between Mackay and Challis. It was responsible for the deaths of two children.
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  1. Can you confirm that this is normal aftershock behaviour? I have lived all my life in this region and my family has lived in Soda Springs for generations and none of them remember anything like this. Some of the aftershocks we have had have been worse than the initial earthquake the beginning of the month. Are we sure these are aftershocks or is there something more to look at?

    1. I have not studied Idaho. Generally aftershocks are of magnitude less than the main event, and in time they decay with a tail. This tail is like a signature for the faults and it is not the same globally. So I hope now you see why I cannot comment. My methods are deterministic and do not rely on statistics. So here you see I do not need to separate main events from aftershocks. Aftershocks can do huge damage as well and thereofore are also important. Aftershocks can last sometimes years! But it depends on the place where the epicenter occurs and the geology of the faults etc.