VOLCANO MONITORING

VOLCANO MONITORING

Interferometric
synthetic
aperture radar
(INSAR)
sees difference
in phase
between
reflected waves
to map the
surface
http://comet.nerc.ac.uk/schoolssar_how.html
Successive
images show
motion

GPS: GLOBAL
POSITIONING SYSTEM
24 Satellites
5-8 overhead most of the world
Transmit radio signals
Receivers on ground record
signals and find their position
from the time the signals arrive
Positions used in many
applications
For tectonics, find motions
from changes in position over
time
Stein & Wysession, 2003

VOLCANO GEODESY
Continuous GPS site on Monserrat,
2.5 km from erupting Soufriere
Hills volcano
Site was subsequently destroyed
by pyroclastic flow and surge

USGS
GPS RESULTS
FOR TAAL
VOLCANO,
PHILLIPINES
Blue dots indicate
short (small) and
long (large) term
modelled
deflationary
volcanic sources
Vectors indicate
long term velocity
(red, observed;
black, modelled)
Deformation
reflects fluid
withdrawal
beneath SE rim of
caldera
M. Hamburger

LONG VALLEY,
CALIFORNIA
Huge eruption 760,000 years
ago formed Long Valley Caldera
and ejected flows of hot glowing
ash(pyroclastic flows), which
cooled to form the Bishop Tuff.
Wind-blown ash from eruption
covered much of the Western
U.S.
Remains active and may erupt
again, so is monitored
USGS

Volcanic gas hazard zone,
Mammoth Lakes,
California
Usage of the Horseshoe lake area is restricted because emissions
of CO 2 , a volcanic gas, caused trees to die and sickness to people.
Other evidence for continued volcanic activity includes
earthquakes, ground deformation, and small eruptions within
the past 1,500 years.

PUZZLING FALSE ALARM
DEFORMATION, EARTHQUAKES, BUT NO ERUPTION
LOTS STILL TO BE LEARNED
GPS showed rate of
surface deformation
increased by more
than an order of
magnitude from July -
December 1997
Newman et al., 2001
Increased
deformation rate led
increase in seismic
moment by several
months, an
observation with
important
implications for
hazard monitoring

“Mike Roark - Tommy Lee Jones!
Invincible head of Emergency
Management for Los Angeles. He
does not understand basic
geology, but has bionic vision.”
“After much disbelief that the glowing
red stuff could be lava, the flow
obligingly travels along Wilshire Blvd.
Roark and friends stop it using
concrete pylons and cars.. .Close to its
defeat, the volcano takes pot shots at
people's crotches, but it's too late. The
lava flows into the ocean. Rather than
seeing "the coast is toast," L.A.
survives and gets a new tourist
attraction.
If you believe this film bears any
resemblance to reality, it's probably
because you live in L.A.”
http://www.badmovies.org/othermovies/volcano