Seismogram (CPW), 112 km (70 mi) NW of Mount St. Helens, May 18, 1981
Detailed Description
Annotated seismogram indicates the signals for a Low-Frequency (LF) volcanic earthquake, relative quiescence, and then harmonic tremor as the eruption of May 18, 1980 accelerated. Each horizontal line represents 15 minutes of time.
Sources/Usage
Public Domain.
CPW seismic station
Related
1980 Cataclysmic Eruption
Magma began intruding into the Mount St. Helens edifice in the late winter and early spring of 1980. By May 18, the cryptodome (bulge) on the north flank had likely reached the point of instability, and was creeping more rapidly toward failure.
Related
1980 Cataclysmic Eruption
Magma began intruding into the Mount St. Helens edifice in the late winter and early spring of 1980. By May 18, the cryptodome (bulge) on the north flank had likely reached the point of instability, and was creeping more rapidly toward failure.