Want to study craters? Geologists grab explosives and make some

Ars Technica » Scientific Method 2012-11-12

Enlarge / View from the edge of Kilbourne Hole in New Mexico—an example of a maar crater.
Scott K. Johnson

While craters cover many other bodies in the solar system, plate tectonics and weathering continually renew the Earth’s surface, preserving its youthful beauty. Still, that process doesn't happen overnight, and there are many craters to be found on our planet. Some record violent impacts with meteorites, and others formed during a variety of volcanic eruptions.

Maar craters, like the one pictured above, are created when fingers of magma beneath the surface of the Earth interact with groundwater, causing a violent explosion. Measuring the size of a meteorite impact crater can provide a lot of information about the size and impact angle of the meteorite. But when it comes to maar craters, geologists have been unsure just how much information about the eruption can be gleaned from the remnant crater.

Part of the problem results from the explosion being able to occur at a range of depths. An explosion of the same size could create a very different crater at the surface depending on how deep it occurs. To complicate matters further, there can sometimes be multiple eruptions beneath the same crater.

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