There’s a volcano in Russia. Well, there are a lot of volcanoes in Russia, out on the Kamchatka peninsula, across the Bering Sea from Alaska, right on the ring of fire. In fact, Kamchatka is kind of known for its volcanoes and not a whole lot else it seems.

Those volcanoes are incredibly active. After all, the Pacific plate is subducting under the North American plate along the peninsula, causing an arc of volcanic activity.

Wait, Beth. Did you say “under the North American plate”? Yes, yes I did. The North American plate goes all the way around the Bering Sea. That part of Russia is on the same plate as we are. It’s a bit mind-boggling.

Anyway, the volcanoes on the peninsula are very active. There are thirty active volcanoes in all, and at the current moment, eight of them are erupting, including the one involved in our top story today: Shiveluch. Shiveluch has had over forty violent eruptions in the past 10,000 years, and while the last major blast was in 1964, it has been constantly erupting for more than 20 years now. It’s considered the most explosive volcano in the world and scientists want to understand why, so a team set about to collect what we call “primitive magma” that had been preserved as small nodules in larger bits of rock that had erupted. Kids, do not try this at home.

Primitive magma is magma that basically crystallized underground a long time ago and didn’t undergo the chemical changes that occurred later in a volcano’s life. So the volatile content — all that pressurized gas and liquid — is frozen in time and can tell us about the past conditions underground. If we can figure out what those past conditions were, we might understand what changes happened and use that to predict how other volcanoes may change over time.

Seriously, it’s amazing what you can learn from tiny crystals in rocks.

The team analyzed the minerals in the nodules and found that the water content by weight was in the 10-14% range. Eight percent water is considered super hydrous for subduction zone volcanoes, and 4% is considered average. These results were pretty striking and mean there must have been a lot of water underneath Shiveluch, more so than expected from a magma pool being hydrated by subducted wet rocks. It also means that the magma was at a lower temperature than usual.

As co-author Michael Krawczynski explained: The only way to get primitive, pristine materials at low temperatures is to add lots and lots of water. Adding water to rock has the same effect as adding salt to ice; you’re lowering the melting point. In this case, there is so much water that the temperature is reduced to a point where amphiboles can crystallize.

Amphiboles are a set of minerals that form at known pressures and temperatures as magma cools, and they are considered hydrated minerals due to their hydroxide content.

These results were published in the journal Contributions to Mineralogy and Petrology and could help us understand how the global water cycle works and possibly even give us some insight into the plumbing systems of other volcanoes.

More Information

Washington University in St. Louis press release

“Evidence for superhydrous primitive arc magmas from mafic enclaves at Shiveluch volcano, Kamchatka,” Andrea E. Goltz et al., 2020 November 18, Contributions to Mineralogy and Petrology