Seismic activity has been quite varied in character during this period and has included small volcano-tectonic earthquakes in addition to long-period and rock fall signals. Two of the volcano-tectonic earthquakes were large enough to be located - both were at depths of c. 1.2 km, one beneath the crater area and the other east of Windy Hill. Rock fall signals continue to dominate the record at the Chances Peak seismometer, whilst the Gages record shows numerous moderately sized long-period events as well as some rock fall events.
The southern and eastern EDM triangle, O'Garra's - Galway's - Chances Peak and Long Ground - Whites - Castle Peak, were measured today. Only small changes were detected in the line lengths since yesterday, continuing the trends of the past several months. The EDM reflector on the Gages Wall was cleaned this afternoon after being covered with ash and the western triangle will be re-occupied as soon as visibility allows.
In excellent viewing conditions for much of the day, visual observations were made both from the helicopter and from Chances Peak. Dome growth appears to have switched over the past couple of days from the northwestern and central parts of the dome to the eastern, northeastern and southwestern parts. Abundant rock falls from these areas were seen and heard, and strong incandescence (glowing) was reported last night (14 March) from Harris, the airport and Long Ground. The highest part of the dome has grown only 75 cm in the past 4 days, indicating that vertical growth in this area has stopped for the time being. Steam and volcanic gases continue to be emitted from the dome at a high rate.
Gas and particle samples were collected from the Tar River area and from sites in Plymouth today.