Study shows that periods of seismic quiet occur immediately before eruptions and can thus be used to forecast an impending eruption for restless volcanoes. The duration of the silence can indicate the level of energy that will be released when eruption occurs. Longer quiet periods mean a bigger bang

See the source article by following the link below:
Study shows that periods of seismic quiet occur immediately before eruptions and can thus be used to forecast an impending eruption for restless volcanoes. The duration of the silence can indicate the level of energy that will be released when eruption occurs. Longer quiet periods mean a bigger bang