GRAND RAPIDS, Mich. (WOOD) — “Ask Ellen” is usually mostly about meteorology, but this time it’s more about geology.
Azelia wanted to know, “Can volcanoes form in Michigan?”
Since I am not a geology expert, I consulted a geologist — and she just happens to be my sister.
WHERE DO VOLCANOES USUALLY OCCUR?
According to Oregon State University, these are the three main places a volcano originates:
- A hot spot — A place in the mantle of the earth that is thinned enough for magma to reach the surface.
- Divergent plate boundaries — A place where two tectonic plates of the Earth are moving away from each other, allowing magma to bubble up into the space left between the departing plates.
- Convergent plate boundaries — A place where two tectonic plates are coming together and one is forced under the other. The plate that is forced further down toward the center of the earth begins to melt and bubble up under the other plate.
CAN A VOLCANO FORM IN MICHIGAN?
Michigan is in the middle of a tectonic plate, not on the fringe. This means we are likely spared from plate interaction-induced volcanoes like the ones formed by divergent or convergent boundaries.
A hot spot, on the other hand, could form anywhere in the world where the upper mantle wears thin. According to Oregon State University, the location of hot spots is not well known.
While it is highly unlikely there is one lurking below Michigan, one could theoretically form over many, many, many, many years — so the chances for a new Michigan volcano are not zero.
ANCIENT VOLCANOES IN UPPER PENINSULA
While researching volcanoes and talking with a few geologists, I learned that there are in fact ancient volcanoes in the Upper Peninsula. They formed 1.1 billion years ago. In fact, the reason we have the copper mines in the U.P. is a result of the volcanoes that formed there.
According to the Iowa Geological Survey, “the Earth’s crust split across part of the North American continent. This tear or rift, known as the Midcontinent Rift System, extended for 950 miles from what is now Lake Superior to Oklahoma, and was on its way to becoming a full-fledged ocean when the process halted. Rocks deposited during the rift’s formation can be seen today surrounding Lake Superior, including basalts along Minnesota’s North Shore and sandstones along Wisconsin’s Bayfield Peninsula.”
Lava filled this rift and eventually turned into basalts. Had the rift continued, there would be an ocean that filled in between Minnesota and Michigan.
But the rift stopped just as soon as it began, leaving us with a scar on our landscape and a history of volcanic activity right here in the Midwest.