An earthquake is a sudden and often violent movement of the earth’s crust due to intense energy build-up or volcanic activity. Seismic waves are released which is what makes the ground shake.
The Earth is made up of tectonic plates. Where these plates meet are fault lines. The most notable one in the United States is the San Andreas Fault line in California. It separates the Pacific plate from the North American plate and this area is the most active for our country. It happens to be along the Ring of Fire, which is where ninety percent of the Earth’s earthquakes happen.
Earthquakes that happen along the San Andreas fault line can be violent and deadly. Take San Francisco in 1989 for instance… a magnitude 6.9 caused 63 deaths, nearly 3,800 injuries, and an estimated six billion dollars in property damage. The earthquake lasted for only fifteen seconds.
A notable and recent earthquake on the east coast that you may remember was in August of 2011. It was in central Virginia and clocked in with a magnitude of 5.8. It caused cracks and damage to the Washington Monument that took almost two years to repair. Luckily, there were no deaths and only minor injuries but there was around 200 million dollars worth of damage. This one was felt in over a dozen US states and even a few Canadian Provinces.
East coast earthquakes tend to be felt further out from their epicenter mainly due to the type of rock. The east coast tends to have older rock and is hundreds of millions of years older than west coast rock..The fault lines on the east coast have had time to heal which means seismic waves can travel through them easier and go further. This is opposed to the west coast where the fault lines are fresher and broken apart… slowing the seismic waves down.
We have small and older faults underneath us here in North Dakota. This is a map of those fault lines. They’re not very active, meaning they don’t move much to where we can feel the. But they have been the source of a few earthquakes here.
We’re one of the states that are least likely to see an earthquake. The North Dakota Geological Survey says we average an earthquake in our state or record an earthquake from further away about once every ten years. We have seen 13 in recorded history and most stayed below a magnitude 3.7.
The strongest ever recorded in North Dakota was in Huff at a magnitude of 4.4 on July 8th, 1968. It wasn’t violent at all. The Bismarck Tribune wrote about how it trembled and startled the residents of the Capital City.
Another interesting earthquake tidbit is that if your home were to be damaged by an earthquake, your standard home owner’s insurance policy won’t cover you. You have to buy earthquake insurance. Luckily, earthquakes are rare in North Dakota but you can certainly ask your insurance agent about that coverage for peace of mind.