Earthquake strikes America's Heartland above ancient volcanoes

"Although Kansas has no active volcanoes, the region marks the southern reach of the Midcontinent Rift System, a massive tectonic event that nearly split North America apart in Earth's distant past. When magma forced its way through the crust during that period, it left behind hardened igneous rock and deep fractures that remain buried thousands of feet underground."

"The earthquake near Assaria was associated with the Humboldt Fault Zone, a major structural feature stretching across eastern Kansas. Geologists say the fault is made up of a series of fractures and buried faults formed hundreds of millions of years ago. While it is relatively quiet compared with faults in more seismically active regions, it remains capable of producing small to moderate earthquakes when stress builds along its hidden fractures."

"Scientists say the ancient scars from both the Midcontinent Rift and the Humboldt Fault still matter today, as the North American plate is constantly under slow-moving stress. That pressure tends to concentrate along pre-existing weaknesses in the crust, and if enough strain builds, the rock can suddenly slip, releasing energy in the form of seismic waves."

A 3.5-magnitude earthquake occurred near Assaria, Kansas on Wednesday afternoon, detected in an area underlain by ancient volcanic rock. Kansas sits above the southern reach of the Midcontinent Rift System, a massive tectonic event from Earth's distant past that nearly split North America apart. The rift left behind hardened igneous rock and deep fractures thousands of feet underground. The earthquake was associated with the Humboldt Fault Zone, a major structural feature stretching across eastern Kansas composed of fractures and buried faults formed hundreds of millions of years ago. Though relatively quiet compared to seismically active regions, the fault remains capable of producing small to moderate earthquakes when stress accumulates. The North American plate experiences constant slow-moving stress that concentrates along pre-existing crustal weaknesses, potentially causing rock to slip and release seismic energy.

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