[Rockhounds] Why Can’t We Predict When a Volcano Will Stop Erupting?

[Kreigh Tomaszewski]

On September 19, Cumbre Vieja—a volcanic ridge covered in the rocky scars
of past paroxysms—erupted
<https://gizmodo.com/the-canary-island-s-explosive-volcanic-eruption-in-6-ph-1847707675>
for
the first time in 50 years. Every single day thereafter, molten rock
cooking at nearly 2,000 degrees Fahrenheit has poured from multiple
fissures and vents, frequently accompanied by explosions propelling glassy
ash skyward. Around 2,500 buildings, many of them homes, have been destroyed
<https://gizmodo.com/9-surreal-photos-of-volcanic-ash-blanketing-one-of-the-1847988877>
as
the lava has meandered to the sea, where it continues to build an onyx
delta shrouded in a haze of ash, steam, and acid.

Naturally, the 7,500 people who have had to flee the area want to know when
this tempestuous act of magmatic madness will come to an end.
Unfortunately, volcanologists don’t have an answer to that all-important
query. A similar level of uncertainty arises whenever a volcano erupts,
whether it’s spewing lava and ash near people or far from them.

Volcanologists are starting to get pretty good at forecasting the start of
an eruption
<https://www.quantamagazine.org/seismic-data-helps-scientists-forecast-volcanic-explosions-20210601/>.
If a volcano has been thoroughly monitored for some time, then scientists
get to know what its usual activity is like: the quakes it makes when magma
or hydrothermal fluids move about; the way it breathes in and out and
changes its shapes; the sorts of gases it belches out. If one or several of
those parameters begin to significantly shift, then it may suggest
something sinister is approaching.

When solid observations are combined with a decent knowledge of the
volcano’s eruptive history, volcanologists can at the very least warn those
nearby that an eruption in the next few days or weeks is more probable than
it was previously. But “the end, it’s very difficult to forecast,”
said Maurizio
Ripepe <https://www.unifi.it/p-doc2-2012-200010-R-3f2a3b2e33282c.html>, a
geophysicist at the University of Florence in Italy. Why?

https://gizmodo.com/why-can-t-we-predict-when-a-volcano-will-stop-erupting-1848006734