Page 28 - ARUBA TODAY

A28 SCIENCE
Friday 1 december 2017

Each volcano has unique warning signs that eruption is imminent

Tracy K.P. Gregg, University proving our ability to pre-
at Buffalo, dict eruptions. Now we can
The State University of New collect important informa-
York tion about volcano shape,
(THE CONVERSATION) temperature and changes
Mount Agung in Bali has in those parameters using
been thrusting ash thou- satellites that provide the
sands of feet into the sky view from space. Satellites
for almost two weeks. Lava give volcanologists a good
is burbling at the volcano’s overall view of the volcano,
peak. Indonesian authori- but can’t supply human-
ties have ordered evacu- scale details. Satellite orbits
ations around Agung, typically allow them to pass
while tourists are stranded over a given volcano only
at the closed airport. The once every week or two.
volcano’s flanks are bulg- We still require seismom-
ing from magma trying eters on the ground to
to push its way out, and detect and report earth-
earthquake frequency has quakes caused by magma
been increasing. Heat from moving beneath the volca-
the magma has melted Mount Agung volcano spews smoke and ash in Karangasem, Bali, Indonesia, Tuesday, Nov. 28, no, but seismometers are
snow and ice at Agung’s 2017. too expensive to deploy
summit, causing volcanic Associated Press and maintain everywhere.
mudflows called lahars. It’s show an increase in earth- vations of volcanoes were In contrast, Mount St. Hel- Accurate predictions of
looking like an eruption is quake strength but instead not commonplace then, as ens volcano in the U.S. is volcanic eruptions – par-
imminent… but how do vol- display an increase in el- they are now. We therefore probably the most closely ticularly the size of the
canologists know for sure evation as magma swells don’t know what specific watched volcano on the eruption and whether the
what’s to come? beneath its surface – just as type, frequency or size of planet. Decades of de- volcano will explode or
Each volcano, like each in- air filling a balloon causes it volcanic precursors – that tailed observations allow generate lava flows – are
dividual person, has its own to increase in size. is, events that precede an geologists to make fairly essential for local authori-
unique “personality.” You The best way scientists can eruption – to look for with precise predictions about ties to make life-and-death
may know, for example, determine whether a vol- Agung volcano. Mount St. Helens: a specific decisions about people
that you can tease your cano is about to erupt is to Mount Pinatubo, Philip- pattern of earthquakes, for in the vicinity of an active
brother mercilessly – up study its past behavior: How pines, for example, erupt- example, means that new volcano. If an evacuation
until the point where his did this volcano act before ed catastrophically in 1991; lava will erupt within two is ordered and a volcano
eyebrows crease together it erupted last time? Our before that, its most recent weeks. explodes, lives are saved.
because that means he’s ability to predict eruptions eruption was around 500 We don’t yet know if Agung This happened in the 1991
going to blow his top. But is directly related to the years earlier. Precursors at volcano is currently giving Pinatubo eruption.
do you know what it means amount of historic data we Mount Pinatubo included us two weeks, two months If an evacuation is ordered
if my eyebrows crease to- have for a given volcano. ash explosions at the sum- or two years (or more) of and the volcano doesn’t
gether? (It’s a surefire sign For most of Earth’s ac- mit, increases in the num- warning because we don’t explode, economic losses
I’m thinking really hard.) tive volcanoes, though, ber of vents spewing hot know precisely what it did and human suffering can
Similarly, one volcano might we don’t have detailed gas, changes in the volca- before its 1963 eruption. be catastrophic. This sce-
reveal an imminent erup- information. The last time no’s shape and increases As technology advances, nario played out in Mam-
tion by a sudden increase Agung volcano erupted, in both the frequency and volcanologists and experts moth Mountain, California,
in the frequency and for example, was in 1963. size of earthquakes. Two in collecting and interpret- in 1984, where the local
strength of earthquakes lo- And that was before it was months of increasing activ- ing satellite data (including community lost millions of
cated directly below it. A closely monitored with seis- ity preceded the 1991 par- remote-sensing scientists tourist dollars – and there
different volcano might not mometers. Satellite obser- oxysmal eruption. and geodesists) are im- was no eruption.q