Earthquakes And Coal Blasts Keep Wyoming’s Ground Shaking

The northwest corner of Wyoming is one of the most consistently shaky parts of the country. The Yellowstone Supervolcano constantly causes earthquakes, but usually they're not big enough to be mentioned. On average, Yellowstone has between 1,500 and 2,000 earthquakes each year, but people feel only 5 to 10.

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According to Michigan Technological University, earthquakes with a magnitude of 2.5 or less are not felt, but are recorded. Earthquakes higher than that have a better chance of being felt. That's why, even though thousands happen each year, very few are felt in Wyoming.

READ MORE: Wyoming's Huge Earthquake Numbers

Yellowstone isn't the only part of Wyoming with a lot of shakin' goin' on. The eastern side of the state is also shaking, but not from earthquakes caused by the natural shifting of the earth or the movement of hydrothermal fluids.

In the Powder River Basin Region, things shake quite often from regulated blasts during coal mining. The size of these tremors ranges from 2.5 to 3.7 on the Richter scale, and some can be felt from miles away.

READ MORE: Wyoming's Natural Resources Impact The State's Economy. 

The coal mining industry is essential to the Wyoming economy, so many safety regulations are in place to ensure blasts are conducted safely and in an environmentally sound way. These blasts occur from Gillette, WY, south to just a few miles south of Wright, WY.

You may be wondering why these mining blasts happen. In the multi-step process of removing coal, blasting is an integral part.

• Coal in Wyoming is uncovered and removed by large machines in a process called surface mining.
• Before the coal can be removed from the ground, the topsoil and dirt above it are removed using scrapers. This soil is usually removed ahead of the pit and carried behind to be placed on top of reclaimed areas or backfilled.
• ***The dirt that lies on top of the coal (overburden) follows the same pattern. The overburden is approximately 120 feet thick and is excavated in three 40-foot benches. This is the step where blasting is used. Holes are drilled into the overburden, and explosives are used to break it up for removal.
• After the overburden is removed, it’s carried behind the pit and placed in the spot where coal was removed. Now the coal is exposed and can be dug out.
• Once the coal has been mined, it’s processed.
• Processing begins in a preparation plant where it’s washed and cleaned to remove contaminants like rocks, ash, sulfur, and other substances.
• After cleaning, the coal goes through a variety of processes, including the removal of foreign material and screening for size. Large pieces will be crushed or pulverized into a more manageable and practical size.
• After the coal is processed, it is cleaned again and transported by trucks and trains to wherever it is needed. Wyoming coal is transported to more than 30 states.

So, you could say that Wyoming is full of movers and shakers and is just as active below the surface as above.