Aon Benfield UCL
Hazard Centre
Forecasting Volcanic Eruptions
Summary. Short-term forecasts of eruptions are crucial for protecting lives and property at active volcanoes. They are essential also for mitigating the impact of eruptions
on critical transport facilities, including international aviation routes. Through theoretical analyses and new studies of the crust beneath volcanoes, the ABUHC is developing
and implementing models for reliable eruption forecasts.
1. Pathway to an eruption
High-impact eruptions normally occur at volcanoes that have been quiet for several generations (below, left). When such volcanoes reawaken, they must break open a new
pathway through the Earth’s crust before magma can escape at the surface. The ABUHC is leading two research themes for investigating how the crust breaks beneath
volcanoes: developing new models to interpret combined rates of stretching and fracturing – as monitored by deformation of the ground and by local seismicity; and using
deep drilling through a volcano to investigate the detailed structure of the crust.
Earthquakes per Day (day-1)
1600
Soufriere Hills, Montserrat
2
Peak Rate, DN/dt = A exp [B(S /YS*)N]
1200
ERUPTION
800
400
0
1
2. Precursors to eruptions
Increasing pressure in an underground body of
magma causes the overlying crust to distort and to
break. Changing rates of distortion and fracturing
are thus key signals to monitor before eruptions.
Distortion and fracturing are distributed unevenly
because of local variations in the crust’s
mechanical properties. We have combined
conventional analyses of how intact rock deforms
(e.g., elastic behaviour) with a new model that
describes how quantum processes determine the
probability of local fracturing. The results yield
preferred combinations of changing rates of
deformation and of earthquake occurrence from
days to years before an eruption.
6
11
16
Time (Days after 31 Oct 1995)
Chaiten, Chile, 2008. First eruption for c. 9,500 years. (Photo: UPI.)
N
Campi Flegrei
Naples
Vesuvius
3. Forecasting eruptions
The forecasting models perform well against test
data from previous eruptions, such as the 1995
reawakening of Soufriere Hills, on Montserrat,
for the first time in 350 years (above, left).
Capri
On 22 September 2011, the ABUHC used the new
model to warn that a volcanic eruption could occur
during the first fortnight of October at El Hierro
(above), the most westerly of the Canary Islands.
The island had previously been quiet for at least
200 years. On 10 October, a submarine eruption
began off the south coast of the island (above,
inset).
1430s
4. Drilling into volcanoes
Changing elevation of columns at Serapis
Campi Flegrei is a densely-populated volcanic
complex that covers 200 km2 west of Naples in
southern Italy (above). It has experienced
alternating periods of subsidence and uplift for
at least 2,200 years (left). ABUHC studies have
related the behaviour to long-term subsidence
being interrupted occasionally by uplift due to
the intrusion of magma about 2.5-3.0 km beneath
the surface. The complex has recently been
undergoing the first episode of net uplift to have
occurred since its last eruption in 1538. An
urgent question is whether Campi Flegrei is again
preparing to erupt.
The potential for magma to erupt is controlled
by structures evolving in the crust during uplift.
The ABUHC is a lead partner in the Campi Flegrei
Deep Drilling Project, which will drill boreholes
to depths of 3.5-4.0 km during 2012-13 (above
and right). The borehole data will be used to
simulate patterns of crustal uplift and, combined
with our models of eruption precursors, will yield
enhanced procedures for forecasting the next
eruption.
2002
Further Reading. (1) Forecasting eruptions: Kilburn CRJ (2012) J Geophys Res, 117, doi:10.1029/2011JB008703 (2) Campi Flegrei: Woo JYL, Kilburn CRJ (2010) J Geophys Res, 115, doi:10.1029/2009JB006913.
More information?
Contact: Christopher Kilburn (c.kilburn@ucl.ac.uk).
Aon Benfield UCL Hazard Centre, University College London, Gower Street, London WC1E 6BT, UK
Helping the vulnerable protect themselves