Volcano Watch — Volcano Watch (no. 1)

The U.S. Geological Survey's Hawaiian Volcano Observatory reports that Kīlauea Volcano continues to erupt from the Kupaianaha vent on the East Rift Zone. Active flows are located along the western edge of the flow field between the 1,100- and the 60-foot elevation. During the week, the flows destroyed two unoccupied houses and threatened several others in the Royal Gardens subdivision. Kupaianaha vent is sealed over, and lava is transported in an underground tube from the vent to the active surface flows.

We have recently refined our methods of measuring the volume of lava erupted from the Kupaianaha vent. Geophysical instruments that detect the volume of lava as it flows through the lava tubes yield a much more accurate number than earlier estimates, which were obtained from mapping area of the flow field and estimating its thickness.

Using the new method, the volume of bubble-free lava within the tube has averaged 150,000, plus-or-minus-30,000, cubic meters per day over the last six months. The new number is not strictly comparable to the long-standing estimate of 500,000 cubic meters per day because the latter included a large volume of gas bubbles and void spaces within the lava flows. As yet, we have no evidence that the eruption rate has changed significantly since Kupaianaha began to erupt in July 1986, but the new method has already allowed us to detect short-term fluctuations in the lava volume.

During a typical week, 300 to 400 located earthquakes occur beneath the Island of Hawai`i, as recorded on the Hawaiian Volcano Observatory seismic network. However, only a few have magnitudes greater than 3.0, roughly the threshold for felt earthquakes. This past week only two such earthquakes occurred; both were located on the south flank of Kīlauea Volcano.