Tasmanian scientists
have pioneered a new method to help predict when volcanoes will erupt,
analysing data from the 2018 eruption of Kilauea volcano in Hawaii.
University of
Tasmania’s School of Physical Sciences adjunct researcher Dr Gerrit Olivier and
Dr Rebecca Carey from the Centre for Ore Deposit and Earth Sciences (CODES)
joined colleagues from France, UK and America to analyse data obtained from the
eruption in a bid to better understand and predict when volcanoes will
erupt.
Using Kilauea volcano
as a case study, researchers analysed background vibrations, resulting from the
spluttering of the lava lake and ocean waves hitting the island’s shore, to
measure tiny changes in the speed that vibrations (or seismic waves) travel
through the volcano.
These changes in
wavespeed revealed a dramatic change of the magma plumbing system inside the
volcano 10 days before the May 3 eruption last year.
“The volcano is
constantly bulging and contracting as the pressure inside the magma chamber
changes,” Dr Olivier said.
“The behaviour of the
seismic wavespeeds are initially quite predictable. When the volcano bulges,
the speed at which the vibrations travel through the volcano increase slightly
as material is compressed. On the other hand, when the volcano contracts these
wavespeeds decrease.
“What we found is
about 10 days before the eruption this behaviour changed quite dramatically.
“The volcano was
still bulging due to the build-up of pressure inside the magma chamber, but the
seismic waves were slowing down quite dramatically, instead of speeding up.”
Volcanic eruptions
generally occur when pressure within the magna chamber exceeds the strength of
the surrounding material. The researchers think that this change in the
behaviour of the wavespeeds could be a sign that an eruption is imminent.
“We think that this
is a good indicator that the volcano isn’t able to sustain the pressure inside
the magma chamber anymore, that the bulge is too big and it starts breaking the
material around the magma chamber which ultimately leads to the eruption,” Dr
Olivier said.
Although these
changes have been shown for some eruptions at other volcanoes in the past, the
researchers were the first to show that these changes occur due to weakening of
the material inside the volcano prior to an eruption.
Kilauea is monitored
by the Hawaiian Volcano Observatory and is incorporated into one of the world’s
most technologically advanced geophysical monitoring networks.
The 2018 Kilauea
eruption was the largest at the site in 200 years. The eruption on May 3 last
year saw 800 million cubic metres of lava flow for three months and the
destruction of more than 700 homes.
The research, , was published in Geophysical Research Letters.
