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Hybrid Event
Sometimes a volcano-tectonic (VT) event triggers a long-period
(LP) event, and vice versa. A seismic signal that contains a
mixture of both types is called a hybrid.
This hybrid event is a VT event that triggered an LP event.
Notice how the signal is bunched up more at the beginning than
it is later on. The first part of this signal shows the VT
event; later, the less-bunched (lower frequency) signal of the
LP event appears.
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Because LP events often begin with signals that look very similar to
those at the beginning of a hybrid, it is usually difficult for
seismologists to distinguish between the two.
To tell one from the other, seismologists look closely at several
seismograms of a single event, as recorded by seismographs placed at
various locations. If the first part of the signal looks similar on
all of the seismograms, they probably have an LP event.
Volcano-Tectonic Event
| Long Period Event |
Tremor |
Hybrid
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