New monitoring developments in Dominica

Since the last report was issued on April 22 there have been two new developments. We have installed an extra seismograph station at Hillcrest Estate House in northern Dominica (DHCT on the map below). This station is in the middle of the source zone of the current activity and will improve the quality of earthquake locations considerably. There are now four state-of-the-art seismograph stations in northern Dominica at the locations shown in the next diagram as solid stars.

Map showing locations of earthquakes (open stars) and seismograph stations (solid stars) in northern Dominica. There are eight more stations off the map to the south.

The closed lines show the summit regions of the two live volcanoes of northern Dominica at the 800 meter contour. A few earthquakes are now happening directly beneath Morne aux Diables but the much larger Morne Diablotins is still seismically inactive. The overall pattern of activity continues to suggest that this earthquake activity is not related to volcanic activity and the alert level at both volcanoes remains GREEN.

In the week of May 23-30 scientists from the Seismic Research Unit visited Dominica to take samples from the hot springs in all parts of the island. One particular result is that the team confirmed the changes in the appearance of the Boiling Lake which has turned almost entirely black. The cause of this is a combination of increased gas emission into the lake and an unusually dry and prolonged dry season which has lowered the level of the lake. This is largely a meteorological phenomenon and is unconnected with the seismic activity further north. Further results will be released when laboratory analyses have been completed and a further visit will be made later this month when UWI scientists will be joined by a team from the University of New Mexico.