Figure from Digital recording of the seismicity of Mount Erebus volcano, November 1994 to June 1996

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Figure 2. Daily histogram of recorded events for 1995 and 1996, including both analog and digital counts for part of 1995. T indicates an approximately 15-minute-long period of high-amplitude, continuous tremor on 31 January 1995. I1-5 indicates 5 successively bigger swarms of shallow earthquakes (possible ice-quakes) which occurred during austral autumn of 1995. E1 indicates a swarm of 150 digitally recorded summit Strombolian explosion events. Note that there is some bias in counting statistics imposed by the digital system, which is more sensitive to swarms containing larger events that are more likely to carry the network (e.g., I5 compared to E1). I6,7 indicate two shallow swarms in early 1996, and LP1-3 mark swarms of both shallow and LP events. E2,3 indicate two swarms of explosion events which occurred one week apart in April of 1996.