A series of earthquakes hit near the New Madrid Fault Line in southeastern Missouri on December 9, 2024, with the strongest registering M3.0 at 06:27 UTC (12:27 local time), according to the U.S. Geological Survey (USGS). This area, known as the New Madrid Seismic Zone, is the most seismically active region in the United States east of the Rocky Mountains.
The sequence began at 06:00 UTC (00:00 local time) on December 9 with an M2.0 quake at a depth of 12.2 km (7.6 miles), located 6 km (3.7 miles) ESE of Hayward (population 131).
Just 8 minutes later, a M2.2 tremor was recorded about 8 km (5 miles) ESE of Matthews (population 628), at a depth of 19.2 km (12 miles).
The largest earthquake in the sequence, an M3.0, struck near Howardville (population 367) at 06:27 UTC (00:27 local time), at a depth of 7.8 km (4.8 miles).
By 12:25 UTC, M2.1, M1.8, and M1.9 quakes had been registered, followed by the final earthquake at 13:30 UTC (07:30 local time) — an M2.2 near Marston (population 477), Missouri, at a depth of 8.4 km (5.2 miles).
The New Madrid Seismic Zone is one of the most seismically active regions in North America east of the Rocky Mountains. However, swarms like this one are common in the area and don’t necessarily point to a larger earthquake.
These swarms typically consist of clusters of small to moderate earthquakes occurring over a short time. They are usually caused by the gradual release of tectonic stress along fault lines or changes in subsurface conditions, like fluid movement within the Earth’s crust.
Though the New Madrid Seismic Zone has produced some of the largest earthquakes in U.S. history, modern monitoring indicates that smaller swarms are fairly frequent.
The zone experienced 3 massive earthquakes between M7.0 and M8.0 from 1811 to 1812. These events caused widespread destruction and were felt as far as Cincinnati, Ohio; Charleston, South Carolina; and New Orleans, Louisiana.
Earthquakes in this region occur along a complex network of faults within the Reelfoot Rift, an ancient geological feature formed about 500 million years ago. The faults are buried beneath layers of sediment, making seismic activity difficult to predict.