Table 1.1.

Characteristics of the phases of extrusion and pauses

PhaseDatesDuration (days)Volume (106 m3)Extrusion rate (m3 s−1)Character
115 November 1995–10 March 19988463314.54 month precursory phreatic episode. Accelerating dome growth with collapses and explosions common
1–2627Increased dome collapses and mild explosive activity after 3 July 1998
227 November 1999–28 July 200313393362.9Largest dome built to date after two major collapses. Late increase in pyroclastic flows, ends in wholesale collapse of dome. Two short intervals of no extrusion
2–3735Very low residual activity until April 2005
31 August 2005–20 April 20076272825.3Precursory phreatomagmatic. One wholesale collapse, ends with a large dome in place
3–4465Very low residual activity until May 2008
428 July 2008–3 January 2009158392.9Two short episodes (28 July–early September and 3 December–3 January). Explosions and extrusion on the western flank of dome
4–5273Very low residual activity until October 2009
59 October 2009–11 February 2010125746.8Extrusion to the west, south and north. Explosions later. Ends in large north-directed collapse
  • *Averaged over the second episode of extrusion in Phase 4.

  • Averaged over both episodes of extrusion in Phase 4.