********************************* Montserrat Volcano Observatory Report for the period midday 17 November to midday 24 November 2006 From: Dr Vicky Hards <vicky@xxxxxx> ********************************* Visual observations of the dome summit have been limited during the period due to low cloud base. Nevertheless, growth appears to have continued towards the northeast. At the beginning of the period two cracks were observed in the curved back of the eastward-facing shear lobe on the dome summit, and there was ash venting from the lower (western most) one. Rockfalls and small pyroclastic flows, predominantly affecting a sector from southeast to northeast, have continued and at least one appeared to reach the sea down the Tar River Valley at around 13:00 (local time) on 23 November. Small pyroclastic flows have also been observed reaching into the upper reaches of Tuitts Ghaut. The most notable event of the period was a small explosion event resulting in an ash plume reaching around 5-700m (1,700-2,300 ft) and pyroclastic flows in the Tar River Valley. There have been no significant changes over the reporting period. Seismicity remains dominated by rockfalls and small long period earthquakes. The seismic network recorded 452 rock fall signals, 71 long-period rockfall signals, 124 long period earthquakes, 1 hybrid earthquake and 1 volcano-tectonic earthquake The rockfall signals recorded in the last 3-4 weeks often contains larger amplitude waves than previously, probably due to the increased height of the dome (greater gravitational energy). The recorded sulphur dioxide flux for the reporting period was slightly higher than it has been in recent weeks, ranging from 508 to 1,167 tonnes/day (t/d), with an average of around 845 t/d. This is above the long-term average (now about 520 t/d) for the eruption. The alert level remains at 3. Residents of Montserrat and visitors to the island are advised to tune into ZJB Radio for up-to-date information on the volcano. Access to all areas south of Richmond Hill, and south of Jack Boy Hill to Bramble airport and beyond is prohibited at all times. The daytime entry zone, comprising the top part of St. George's Hill, is closed. The maritime exclusion zone around the southern part of the island extends 4 km off shore from Spanish Point to Roches Yard on the east side of the volcano, 2 km offshore from O'Garras to Gingoes on the south- west, and 200 m offshore from Plymouth. For further explanations of the volcanic phenomena described, and information about the Soufrière Hills Volcano and the ongoing eruption, please look at the MVO website: http://www.mvo.ms <http://www.mvo.ms/> . Noon, 24 November 2006. ******************************** Dr Vicky Hards Director Montserrat Volcano Observatory P.O. BOX 318 Flemmings Montserrat West Indies. Tel: 1-664-491-5647 FAX: 1-664-491-2423 Email: vicky@xxxxxx <mailto:vicky@xxxxxx> http://www.mvo.ms <http://www.mvo.ms/> ********************************* ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
