Earthquakes 101…and is the big one coming?

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WEST MICHIGAN — We’ve been hearing plenty about earthquakes over the last few months around the world, but rarely do we have much earthquake news to talk about here in Michigan. Yes…we have felt the ground shake from time to time here in Michigan…so not unusual, but rare to have it actually occur within the state. The last time we had a sizable quake occur in the state was August 9, 1947. We measured a 4.6 on the Richter Scale at that time across southern lower Michigan.

To understand what’s happening, we need to explain the basics. We know lithopspheric plates are moving each and everyday across the surface of the earth. These plates can converge with one another, diverge, or slip past each other (transform fault). Where an oceanic and continental plate converges, one plate is being subducted or pulled underneath another plate and literally being destroyed. If two continental plates converge, mountains can form and earthquakes can result. Our West Michigan quake was not the result of either of these.

boundaries

In fact, there may be several very small, inactive faults, or cracks in the rock below the surface in Michigan, but there are simply no forces acting on them to create routine earthquakes. There are two known seismic zones in the Midwest. One in Indiana known as the Wabash Valley Seismic Zone, and the more well-known one called the New Madrid (pronounced Mad-Dread) in Missouri. There’s been plenty of activity in these locations over hundreds of years…in fact about 200 quakes each year occur in these areas. Michigan has felt quakes that originated in these areas, but without a direct active fault here it is rare to see one originate here. We may never know what created the 4.2 magnitude quake around Galesburg on Saturday, but we know a major quake in this state is highly unlikely.

Seismic Zones

According to Western Michigan University Geosciences Professor Dave Barnes “Michigan sits just about in the bulls-eye of about the lowest potential for significant damage to anywhere in the United States. So we have very little to worry about.”

Many have been asking about hydraulic fracking playing a role in this latest Michigan quake, but that too is highly unlikely. Why? Barnes says “there is simply no drill rig in the state that’s ever drilled six miles below the surface. There is no relationship between hydraulic fracturing and this earthquake event.” The depth of this earthquake is between four and six miles.

Where’s the highest hazard or bulls-eye for earthquakes in this part of the United States? (see thumbnail attached to this story) Exactly where the two seismic zones are located to our south/west. While the big one is possible in these areas, Michigan would likely only feel the secondary shake from a larger quake well outside of the state. To restate the obvious, the events that take place with earthquakes around the world in places like Japan, Indonesia, Nepal, Haiti, and California are fundamentally completely different geologically than what can happen in Michigan. We simply lack the tectonic activity and plate boundaries that are present in other parts of the world!

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6 comments

  • Debra Suhr

    I think just because you say it’s highly unlikely that another earthquake would happen isn’t completely true. Yes we may not have a fault line like California why wouldn’t it be possible? Usually when there is a small earthquake doesn’t mean there won’t be one bigger. I’m just saying. I know I’m prepared for a bigger one just incase. My head isn’t in the sand. And you can’t always believe what mainstream media and if there is a other one bigger than this the news isn’t going to tell shit…..just saying.

    • Chris Vanderlip

      Hi Debra, our seismic activity here is incredibly minimal, with the tiniest amount of activity (see links at http://earthquake.usgs.gov/earthquakes/states/?region=Michigan ). Earthquakes are technically possible just about anywhere, but we really are in a region that is very stable geologically, and we shouldn’t expect to see anything significantly bigger than what we saw yesterday in the next million years… give or take 100,000. I wouldn’t spend too much time concerned about it. (FYI and in case you wonder about my credentials, I am a graduate student in geology)

  • diana

    I live here in Ithaca ,Michigan and some of us felt it I myself felt my house shake and my couch I sat on shooked felled everything rumbled it was weird feeling then I found out that it was an earthquake it scared me ….i heard that there is gonna be an earthquake that is gonna break. And seperate the world how much is this true

  • Kyle

    Your info is incorrect…. 3 miles was the depth and i do believe we have seen many drills go this deep. By the way USGS site states quakes like these are due to man made activities… tisk tisk. You guys should be doing better than that