|A picturesque maar crater in Michoacán Mexico.|
|Our experimental maar volcanoes would need to be a LOT bigger to match nature.|
These craters are found all over the planet in a wide variety of environments. The giant Epsenberg maars are in the remote subartic of Alaska. There are maars in the deserts of Turkey and Mexico. You can also find a lot of maars in the tropics, like in the Philippines and Indonesia. While some of them occur in remote locations, like Kamchatka Peninsula Russia or Ukinrek in Alaska that erupted in 1977, many of them are found in the middle of cities. In fact, the city of Auckland in New Zealand is built on top of 53 volcanoes, including ~11 maars. If you live in San Luis Potosi or Morelia in Mexico, Frankfurt in Germany, Rome in Italy or Kagoshima, Japan you are only a short drive away from a maar volcano.
|Eruption of Ukinrek Alaska 1971, USGS.|
Some maar volcanoes occur in isolation, where they are the only volcano in the area, like Ubehebe crater in Death Valley California. While others occur in volcanic fields mixed with other types of volcanoes, like scoria cones and stratovolcanoes.Some maar volcanoes are covered by more recent volcanic activity. Sometimes scoria cones and lava flows occur at the end of the same eruption that formed a maar. Other maars occur inside, or on the flanks of a bigger volcano like Aniakchak caldera in Alaska.
|Google Earth image of Aniakchak volcano, Alaska, USA. Two maars have formed inside the caldera, noted by the yellow pins They are cleverly named Southwest and Northeast maar.|
Do we know where all the maars are on Earth? Nope. There are lots of other circular lakes that can, at first glance, look like a maar: permafrost lakes, sink holes, those crazy holes in Siberia and impact craters. Also, as maars get older they are subject to weathering and erosion. Since they are holes in the ground, instead of big fancy cones, they fill up with sediment and get shallower with time. Lots of maars have lakes in them which only helps them fill with sediment. Other maars get eroded along the edges (Hunt's Hole) and stop looking like nice perfect craters. In wetter environments, the shallow slopes of volcanic ash make for fertile soils, which means that you can find a lot of circular lakes in the middle of farmland that are actually volcanoes. In some locations the ash and rocky deposits are mined for abrasives or road materials. This makes it harder to count maars and know how big they can be. My goal is to look at the maars that we have found and see what we can learn about the type of eruptions that form them by comparing shape, size and environment. The more maars I study, the better. Thankfully satellite imagery means that I can study these volcanoes without having to pay for plane tickets to get to all of these locations. But maybe I'll make it a personal goal to see as many as I can. I think I've visited at least ten already, but that there are many more maars to go.
|Kilburn (top) and Hunt's Hole (bottom) maars in New Mexico.|
|There are 22 maars in this image, plus a stratovolcano and several scoria cones. How many can you spot? Lamongan Volcanic Field on the Island of in Indonesia.|