Government Information Service

The Volcanic Explanation
For The 24 Hour Period Ending 4 PM On Friday August 01, 1997
A Presentation Of The Government Information Services
In Conjunction With The MVO.

The alert level system has been revised by zones.

The Soufriere Hills Volcano has remained at a very high level since 3 am yesterday (Thursday), with intense rockfalls, pyroclastic flows, hybrid swarms and ash being deposited to the west.

72 rockfalls, 91 long-period events (61 of which triggered rockfalls) , 63 hybrids and one volcano-tectonic earthquake were recorded. The swarm of hybrid earthquakes started at 5:30 am today (Friday) and lasted about 2 hours. The frequency was about one per minute during the peak. There were also two other periods of elevated activity yesterday (Thursday) between 4:30 and 6:00 pm and 10:00 to 11:00 pm. Today (Friday) the activity was shorter and not as intense. High amplitude tremor dominated the Lees Yard and St. George's Hill stations during this activity. Pulses of ash plumes were seen every few minutes and seem to come from near the top of Galways Wall but did not seem to be connected to pyroclastic flows and drifted to the west of the volcano. After 2 weeks the Chances Peak tiltmeter is again working and a cyclical pattern of about 10 hours has developed. This is similar to readings during previous periods of activity.

A late evening observation showed no new deposits in Mosquito Ghaut, Tuitts Ghaut, Tar River Valley, or Galways. Gages Valley had some new deposits to just below the Lower Soufriere with spilling into Gages village, Glen Mohr and just to the north of Gages Valley. The pyroclastic flows of the past two days have created an amphitheatre at the top of Gages Valley.

Pyroclastic flows and ash eruptions have increased during the past 48 hours and anyone entering the exclusion zone is at great risk. Residents in the northern or central zones should stay alert and listen to ZJB which will remain on the air all night. Activity may increase without any warning.

Dust masks should be worn where there is still ash. Drivers should drive slowly in ashy areas.

Professor Barry Voight of Penn State University has arrived for a brief visit to the MVO.

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