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

The alert level system has been revised by zones.

The summit of the Soufriere Hills Volcano was not clearly visible today and activity was again dominated by rockfalls and small pyroclastic flows.

Tuitts Ghaut was the location of the small pyroclastic flow seen at 6:20 this morning. None of the other ghauts around the volcano had any new deposits. Rockfalls are now falling over Gages Wall into the valley, as the scree slope of the dome covers the Gages Wall.

55 rockfalls, 3 long-period events and 3 volcano-tectonic earthquakes were recorded today. The volcano-tectonic (VT) earthquakes were recorded at shallow depths beneath English's Crater and were the largest recorded this month. Again broadband tremor of low amplitude were recorded at the St. George's Hill station during the day.

GPS (global positioning satellite) measurements were carried out today at Lees Yard, Waterworks, Garibaldi Hill, and the MVO. The results will be posted when the survey is completed. No EDM (Electronic Distance Measurements) were carried out today. A reconnaissance flight to find new locations for permanent target sites on the sides of the volcano was carried out today.

The dome is continuing its growth and large pyroclastic flows onto all sides of the volcano remain a strong possibility. Recent pyroclastic flows and ash eruptions have occurred with no direct association to seismicity. Mudflows may occur in the Belham River Valley after heavy rainfall. These mudflows are very hot move rapidly and can go further than pyroclastic surges. No one should try to handle or walk on these deposits, they are unstable and retain heat for many weeks. Dust masks should be worn when ash is in the air.

Dr. Keith Rowley left yesterday after a month long tour of duty. Dr. Richard Herd returned after a short break.

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