10 comments on “Craters of the Moon, Idaho

  1. Wow, what an impressive place, and the lavas looking so fresh in the images as if erupted just recently. – I wonder how long one eruptive episode lasted (that produced the 4-5 km3). And, what is an ‘eruptive sequence’ (the 1 cubic mile), is it one eruption like we know it? Great article, thanks agimarc!


    • Howdy Granyia – The part I am somewhat confuse about is the high temperature gabbro deposit underneath the valley. I think it is residual melt from the passage of the hot spot fueling the serial basalt deposits 1 MA or so afterwards. Some of what i read about it indicate that it is quiescent, non-eruptible stuff. If the latter is true, where does the basalt come from? No answer that I know of, which is why I lean toward residual melt. Its a really complex site, moreso with the additional basalt surface flows up the valley following the calderas. Cheers –


    • Howdy Granyia – as I understand it, an eruptive sequence is a series of eruptions that deposit the 4-5 km3, followed by a quiescence for 2000 years or so. Appears that once it starts, it goes like all get out for a while and then peters out for a time. Sooner or later it will stop. One indicator is the increasingly explosive nature of what is erupted, as that indicates evolved magmas. The more evolved the magma, the older the melt generally is unless something is mixing it from below. Cheers –


  2. Another volcano in Japan is entering the scene: Niigata-Yake-Yama, 30km NW of Nagano, near the Japanese coast, has been raised to alert lvl. 2. The volcano takes the form of a lava dome that was built in the 1361 eruption. The volcano is one of the youngest in Japan, its age is estimated at only 3100 years old. The top of the lava dome is cut by fissures where mild phreatic eruptions have taken place in recent historical times. Three major magmatic eruptions have taken place in historical time, in 887, 1361 and 1773, these eruptions were VEI 3-4 and have produced lava and pyroclastic flows that have reached the coast. Since 1773 all eruptions have been phreatic and have come from fissures and craters at the summit and sides of the dome, the last one in 1998. (Thanks, @ShérineFrance!)


  3. Thank you SO much for this article AG! I’m going to Craters of the Moon in a few weeks’ time and haven’t had the time to read up on it (still way too much going on in real life). Lo and behold it’s all here – fantastic story! I can’t wait to go there now (hmm, willl the family share my enthusiasm? – the wannabe geologist son will love it … not so sure about shopaholic wife and daughter though!)


    • Good to hear from you, UKV. Thank you for your kind words. I’ll be interested in hearing how your trip went afterwards. If you guys want to take a look at some manmade interesting things, there is a museum in Arco, Idaho that has several of the nuclear experiments that the INL conducted over the last 50 years. Ladies might not be all that interested, but it should be red meat to techies. Cheers –


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