[Rockhounds] Volcano in Tanzania with weirdest, runniest magma on Earth is sinking into the ground

[Kreigh Tomaszewski]

A volcano in Tanzania with magma that erupts like a garden hose has been
steadily sinking into the ground for the past 10 years, a new study shows,
and the cause could be a deflating reservoir directly beneath one of the
volcano's two craters.

The new research reveals that the ground around the summit of Ol Doinyo
Lengai volcano, which sits along an active rift zone in East Africa,
subsided at a rate of 1.4 inches (3.6 centimeters) per year between 2013
and 2023. This means the *9,718-foot-tall (2,962 meters)*
<https://volcano.si.edu/volcano.cfm?vn=222120> volcano shrank by about 1.2
feet (36 cm) in the timeframe of the study, which was published June 8 in
the journal *Geophysical Research Letters*
<https://doi.org/10.1029/2023GL107673>.

Researchers used data from two satellite systems, Sentinel-1 and
Cosmo-SkyMed, to produce maps showing changes over time in the ground
around Ol Doinyo Lengai. Their maps indicate that a circular patch of
ground around the volcano's northern crater was "moving away from the
satellite with a steady rate of displacement over time," the researchers
wrote in the study.

Ol Doinyo Lengai is the only known volcano on Earth that is *actively
erupting* <https://doi.org/10.1016/j.jvolgeores.2023.107918> carbonatite
magma — extremely runny magma that is saturated with alkali elements, such
as calcium and sodium, and poor in silica. Most terrestrial magmas are rich
in silica, a compound made from bonded chains of silicon and oxygen that
binds molten rock together and *gives it a viscous consistency*
<https://www.livescience.com/planet-earth/volcanos/weird-new-device-measures-how-liquid-lava-is>.
But unlike those other magmas, whose weight is between 45 and 70% silica,
the magma that feeds Ol Doinyo Lengai contains less than 25% silica by
weight, according to *Erik Klemetti*
<https://denison.edu/people/erik-klemetti>, a volcanologist and associate
professor at Denison University in Ohio.

https://www.livescience.com/planet-earth/volcanos/volcano-in-tanzania-with-weirdest-runniest-magma-on-earth-is-sinking-into-the-ground