Jan 7 1999, 4:30 pm - White Island Volcano

Seismic activity at White Island has increased significantly since about 11:15 pm last night. Volcanic tremor levels peaked at around 5 am this morning at a level of about 20 times the background level of the past 2 - 3 weeks and 7 times that accompanying the November activity. Tremor today remains sustained at a level of about 15 times the recent background level.

A surveillance trip to White Island this morning revealed a relatively low level of eruptive activity. A new vent, about 50 m diameter, has formed in 1978/90 Crater located approximately at the site of a crater (Wade Crater) that was very active in the 1980s. Frequent hydrothermal eruptions of black muddy water are occurring in this vent. There are no impact craters around the new vent, which suggests it formed by collapse rather than by explosion. Ash-poor steam-rich plumes to 600 m are being emitted from both this new vent and the vent active during the past month.

At 18:30 on January 6 strong ash emission was occurring from the previously existing erupting vent (report by Pee Jay Charters). Therefore it appears that the increase in seismic activity, formation of the new vent, and decline in ash emission were more or less coincident.

The high level of seismicity combined with the low level of eruptive activity suggests that magma is being intruded beneath the surface. As a consequence, the likelihood of enhanced eruptive activity in the short-term has increased.

At this time of year there are many casual visitors landing on White Island. We recommend that visitors do not approach the area of active vents, which is at the western end of the Main Crater. The expected enhanced activity may produce dangerous explosive eruptions capable of showering rocks and ash over much of the Main Crater floor.

The Alert Level remains at 2.

Dr. Carol Bryan
Duty Volcanologist