VOLCANO MONITORING
VOLCANO MONITORING
VOLCANO MONITORING
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<strong>VOLCANO</strong> <strong>MONITORING</strong>
Interferometric<br />
synthetic<br />
aperture radar<br />
(INSAR)<br />
sees difference<br />
in phase<br />
between<br />
reflected waves<br />
to map the<br />
surface<br />
http://comet.nerc.ac.uk/schoolssar_how.html<br />
Successive<br />
images show<br />
motion
GPS: GLOBAL<br />
POSITIONING SYSTEM<br />
24 Satellites<br />
5-8 overhead most of the world<br />
Transmit radio signals<br />
Receivers on ground record<br />
signals and find their position<br />
from the time the signals arrive<br />
Positions used in many<br />
applications<br />
For tectonics, find motions<br />
from changes in position over<br />
time<br />
Stein & Wysession, 2003
<strong>VOLCANO</strong> GEODESY<br />
Continuous GPS site on Monserrat,<br />
2.5 km from erupting Soufriere<br />
Hills volcano<br />
Site was subsequently destroyed<br />
by pyroclastic flow and surge
USGS<br />
GPS RESULTS<br />
FOR TAAL<br />
<strong>VOLCANO</strong>,<br />
PHILLIPINES<br />
Blue dots indicate<br />
short (small) and<br />
long (large) term<br />
modelled<br />
deflationary<br />
volcanic sources<br />
Vectors indicate<br />
long term velocity<br />
(red, observed;<br />
black, modelled)<br />
Deformation<br />
reflects fluid<br />
withdrawal<br />
beneath SE rim of<br />
caldera<br />
M. Hamburger
LONG VALLEY,<br />
CALIFORNIA<br />
Huge eruption 760,000 years<br />
ago formed Long Valley Caldera<br />
and ejected flows of hot glowing<br />
ash(pyroclastic flows), which<br />
cooled to form the Bishop Tuff.<br />
Wind-blown ash from eruption<br />
covered much of the Western<br />
U.S.<br />
Remains active and may erupt<br />
again, so is monitored<br />
USGS
Volcanic gas hazard zone,<br />
Mammoth Lakes,<br />
California<br />
Usage of the Horseshoe lake area is restricted because emissions<br />
of CO 2 , a volcanic gas, caused trees to die and sickness to people.<br />
Other evidence for continued volcanic activity includes<br />
earthquakes, ground deformation, and small eruptions within<br />
the past 1,500 years.
PUZZLING FALSE ALARM<br />
DEFORMATION, EARTHQUAKES, BUT NO ERUPTION<br />
LOTS STILL TO BE LEARNED<br />
GPS showed rate of<br />
surface deformation<br />
increased by more<br />
than an order of<br />
magnitude from July -<br />
December 1997<br />
Newman et al., 2001<br />
Increased<br />
deformation rate led<br />
increase in seismic<br />
moment by several<br />
months, an<br />
observation with<br />
important<br />
implications for<br />
hazard monitoring
“Mike Roark - Tommy Lee Jones!<br />
Invincible head of Emergency<br />
Management for Los Angeles. He<br />
does not understand basic<br />
geology, but has bionic vision.”<br />
“After much disbelief that the glowing<br />
red stuff could be lava, the flow<br />
obligingly travels along Wilshire Blvd.<br />
Roark and friends stop it using<br />
concrete pylons and cars.. .Close to its<br />
defeat, the volcano takes pot shots at<br />
people's crotches, but it's too late. The<br />
lava flows into the ocean. Rather than<br />
seeing "the coast is toast," L.A.<br />
survives and gets a new tourist<br />
attraction.<br />
If you believe this film bears any<br />
resemblance to reality, it's probably<br />
because you live in L.A.”<br />
http://www.badmovies.org/othermovies/volcano
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