EWR monitors Mt Redoubt in Alaska as a result of the eruption of Redoubt in April 2009. This is the seismic trace of the Japan Earthquake and related Pacific rim activity, as recorded on Redoubt webicorder RSO:
The image below is the current RSO seismic webicorder trace for Mt. Redoubt in Alaska. Tremor activity continues in the Rim of Fire, since the Sendhai earthquake went off on the 10th. This image updates in realtime, to give you an idea of the aftershock scenario from a major quake. The challenge for volcanologists is to separate seismic activity of their target (Mt. Redoubt, in this case) from the background activity from unrelated areas. The red lines on the trace are calibration spikes.
Webicorder RSO_EHZ_AV 24hr. (refresh for webicorder update – Active trace is the very bottom one).