From Ars Technica: 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.