Lava Discharge Rates at Kīlauea Volcano, Hawai‘I, during 2011-2013 Determined from Tandem-X-Derived Topographic Data

Abstract:

The effusion rate of lava from a basaltic volcano is a parameter of critical importance given its direct association with hazard—for example, high effusion rates imply long lava flows. At Kīlauea Volcano, Hawai‘i, numerous methods have been used to quantify effusion rate, including direct observation of lava streams, measurement of gas emissions, geologic mapping, modeling of thermal radiance, and quantification of topographic change. None of these techniques, however, have consistently yielded reliable results since about 2008, due to either changes in the character of volcanism or the expense associated with data collection. Synthetic Aperture Radar (SAR) data from the TanDEM-X satellite mission offer a potential solution to this problem. Differencing digital elevation models (DEMs) derived from temporally sequential TanDEM-X SAR imagery provides measure of elevation change over time due to accumulation of lava across the entirety of Kīlauea’s 100 km² East Rift Zone lava flow field. Summing these elevation changes over the area of an active lava flow and dividing by the time spanned by the TanDEM-X data gives the time-averaged discharge rate (TADR) of lava. The TADR calculated from multiple TanDEM-X-derived DEMs spanning days to weeks at Kīlauea during mid-2011 to mid-2013 suggests a dense-rock equivalent lava discharge rate of approximately 2 m³/s, which is about half the long-term average rate over the course of Kīlauea’s 1983–present East Rift Zone eruption. This result implies an increase in the rate of lava storage at Kīlauea, a decrease in the magma supply rate, or some combination of both with respect to previous years. TanDEM-X-derived topographic maps also provide insights into the four-dimensional growth of Kīlauea’s lava flow field—a dataset not available by other means but important for assessing the factors that control current and future lava flow pathways.