Another earthquake was felt by residents of Challis, Idaho, Saturday morning, triggering rock slides that caused power outages and property damage in the area. Authorities measured the quake at a 4.9 magnitude.
Reports showed the exact location of the quake to be 44.504°N 114.136°W depth=8.2km (5.1mi), and that movement could be felt in Boise, Garden City, Mountain Home, and Eagle.
This was one of a swarm of earthquakes in the same area over the course of the week. Scientists have been able to determine that plates have begun to shift roughly six miles below the earth's surface within the Centennial Tectonic Belt, which extends west from Yellowstone National Park. The belt extends from the area through multiple states.
Yellowstone is known as a hotspot for geologic activity, as it sits atop magma, but researchers say that doesn't explain the increased earthquake activity in Idaho. They do believe that it's far from a coincidence, however.
What is perplexing to scientists is the fact that the shifting plates are so far from those located on the West Coast, where the majority of geologic movement occurs in the United States.
Mike Stickney of the Montana Bureau of Mines and Geology said, "That's the fundamental question that we don't know. It's related to plate tectonics, but no one knows why this is occurring so far from a plate boundary. Nobody understands why these belts are located where they are."
So far, nearly 20 quakes have been reported in the area, the largest upset since a 6.9 magnitude earthquake occurred in the state in 1983. Severe damage, injury, and some fatalities rocked the little community at that time. Residents have currently been reporting rock slides blocking roadways, property damage caused by shifting building material, and residential damage caused by moving furniture. Perhaps the most distressing to those living in the area is not knowing when the next quake will occur and how strong it may be.
Kris Pankow, associate director of the University of Utah Seismograph Stations, said that the main interest in the Idaho quakes is to better understand the Intermountain Seismic Belt. So far, the Idaho quakes have been a complete mystery. Possible causes of the quakes include stretching of the crust or heated water moving about.
Scientists are using the opportunity to analyze such occurrences to further the technology used in measuring earthquake activity, including the means of early detection and warning for local residents.
Currently, no warning has been issued to the sparsely populated area, and residents don't seem to be overly worried, as they have been growing increasingly used to the tremors. Further investigation will continue to ensure that a large-scale quake activity won't catch the population unaware.