Karymsky Volcano, Kamchatka, Russia, 1996-1999
I have been working on Karymsky Volcano for more than 10 years.
This incredible place is a wonderland for volcnaologists and seismologists
exploring volcanic explosions. Here a several hours of seismic data recorded
during three campaigns spanning 1997-1999.
Note that the explosion frequency changes from year to year.
From January 1, 1996 through November 1999, Karymsky volcano was active in a quasi-periodic eruptive mode,
exploding, typically, every 5-15 minutes. This Strombolian activity is not atypical for Karymsky volcano; numerous episodes of
quasi-periodic explosions have been observed in previous eruptive phases.
In August-September 1997 a curious phenomenon was observed near the exploding vent and subsequently
recorded on broadband seismic stations.
During this period, once per hour, on average, initial explosions were followed by a series of
impulsive signals recorded on seismic and infrasonic sensors located 1.6 km from the active vent.
These impulsive signals, their line spectra and apparently harmonic nature, and their
source characteristics have become the subject of some controversy in the volcanic seismology community.
Similar signals at Arenal, Costa Rica,
have been interpreted as emanating from the resonance of a conduit containing a mixed two-phase fluid body
in the upper hundreds of meters in the volcano edifice. Since other volcanoes around the world exhibit
similar behavior,
it is important to develop a general understanding of
these volcanic signals in terms of the complete seismo-acoustic wave field.
An example of Chugging at Karymsky can be seen on this figure where the acoustic
and the seusmic records are displayed together. Note the Acoustic signal arrives after
the seismic signal, as the wave speed in the air is much slower than that in the earth.
