Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 13 April
to 16:00 14 April 1997
The current alert level is ORANGE

Activity has been at a low level for most of the day. A small earthquake swarm occurred this morning. Further rockfalls have been occurring during today through the enlarged canyon in the Galway's Wall.

The main seismic activity today was a small swarm of hybrid earthquakes which lasted from 4:00 am to 10:43 am. Only 11 events were triggered during this swarm. There were no volcano-tectonic or long-period earthquakes and only 20 rockfalls. Low amplitude tremor has been intermittently recorded on the Gages seismometer throughout the day.

Visual observations were limited today by low cloud, but a helicopter flight early this afternoon enabled scientists to get good views of the dome above the Galway's wall. There is a new extrusion of material in the scar left by the pyroclastic flows on 11th April. The scar is rapidly being filled in with the new lava, and rockfalls from the dome are also filling in the chute in the wall. Pyroclastic flow deposits in the White River are now more extensive laterally and also deeper in parts of the valley. The Great Alps waterfall is now entirely covered, suggesting that approximately 10 m or 30 feet of new material was deposited in that area on 11th April. Some of today's rockfalls produced ash clouds which were blown over the southern part of the island.

Results from the GPS survey of the western part of the island completed at the end of last week show no significant changes in the positions of these sites.

The alert level remains at ORANGE and pyroclastic flows could occur without warning in both the Tar River and White River valleys, and surrounding areas remain extremely dangerous. Activity could escalate quickly, and visits to zone C should be kept brief. Zone D should not be occupied again tonight.

Montserrat Volcano Observatory