A series of small earthquakes recently struck the New Madrid Seismic Zone (NMSZ), a 150-mile-long fault line in the Midwest that scientists warn is overdue for a major quake. Between December 6 and 11, the U.S. Geological Survey (USGS) detected eight quakes, primarily in Missouri and one in Tennessee. While the largest measured only a magnitude 3.0, the activity has reignited concerns about the potential for a catastrophic “Big One.”
Details of the Earthquake Swarm
- Locations Affected: Quakes were detected near Howardville, Matthews, Marston, Hayward, and Cooter in Missouri, and one near Ridgely, Tennessee.
- Magnitude: The largest were a 3.0 and 2.6 near Howardville, with others around magnitude 2. Earthquakes below magnitude 2.5 are typically not felt but are detectable by seismographs.
- Timing: Seven of the quakes occurred within a nine-hour span on December 6, and the eighth was recorded on December 11.
The New Madrid Fault
The New Madrid fault spans parts of Missouri, Arkansas, Tennessee, Kentucky, and Illinois. It is one of the most active seismic zones east of the Rocky Mountains and is capable of producing devastating quakes.
- Historical Context: Between 1811 and 1812, three massive earthquakes estimated between magnitude 7 and 8 struck the area, reshaping the landscape and destroying settlements. The last significant quake, a magnitude 6.6, occurred in 1895 near Charleston, Missouri—129 years ago. This makes the fault overdue for another large seismic event.
- Potential Impact: A magnitude 7 or 8 quake in the NMSZ could:
- Kill thousands and devastate cities like St. Louis, Missouri, and Memphis, Tennessee.
- Destroy bridges over the Mississippi River and buckle highways like Interstate 55.
- Rupture oil and gas pipelines, leading to nationwide disruptions.
The Likelihood of a Major Quake
- Predictions: Experts estimate a 40% chance of a magnitude 7 or higher quake in the next 50 years, with the risk increasing annually. Robbie Myers, an emergency coordinator with the Missouri Department of Safety, emphasized the need for preparedness.
Understanding Earthquake Swarms
Earthquake swarms consist of clusters of small-to-moderate quakes over a short period. They are not uncommon in active seismic zones like the NMSZ, but scientists are still investigating their causes. Theories include:
- Fault Slip: Slow slipping of the fault with small sticky patches breaking off.
- Magma Movement: Molten rock pushing through the Earth’s crust, causing rock fractures and tremors.
Preparedness Is Key
While this week’s swarm doesn’t necessarily indicate an imminent major quake, experts stress the importance of readiness. A significant earthquake in this region could have far-reaching consequences, underscoring the need for vigilance and precautionary measures.
