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Monitoring Remote VolcanoesBy Deformation
1992-1999
Courtesy of Amelung, Jonsson, Zebker, and Segall (Nature, 2000)
Causes of Deflation
• Submarine eruption– Should cause deformation signal
• Lateral intrusion– Should cause deformation signal
• Vesicle segregation– Should cause densification = gravity signal
• Drainback
Continuous Network
Deflation
Accelerating Inflation
October 20, 2005 Eruption
Decelerating Inflation
Cerro Azul Transient
October 20, 2005 Eruption
April 16, 2005 Trap Door Fault
Accelerating Inflation
Trapdoor Fault
GV06
October 23, 2005
Eruption
Continuous Network
2005Lava
Decelerating Recovery
Before AfterUpper balloon will inflate at decelerating rates
Q = r P
4
8L
Poiselle Flow
Cerro Azul Transient
Cerro Azul Event
Eruption End
Eruption Start
2009 Model
+40.1 cm/y
Inflation
Deflation
Eruption
Conclusions
• Intrusion is forming by unsteady but continual supply of magma.
• Feedback between faulting of the roof, eruption, and resupply.
• Feedback between pressure, volume, and degassing.
• Dikes do not form along faults!
Fernandina
Sierra Negra
Extremely remote: Largest wilderness tropical island in the world
Inhabited and developed
Green = Observed
Red = Inflation by InSAR
Blue = Coeruption
2002-2006 GPS
Questions
• What causes the fluctuation in magma supply?
• Why do dikes form on the hinge, not the fault?
• What controls faulting vs. eruption?• Why didn’t faulting relieve pressure?• How does the feedback between pressure,
volatiles, and deformation work?