LAVA FLOW MAPPING USING RADAR INTERFEROMETRY: AN EXAMPLE FROM KILAUEA VOLCANO, HAWAI`I

A satellite-based method for mapping the emplacement of lava flows is being developed using radar interferometry (InSAR) data. The goal of the project is to use coherence maps derived from individual interferograms to show the progressive development of lava flow fields. Where new lava has been emplaced, the interferogram will be incoherent. These techniques have been reported previously (1) but our work is unique because it exploits multiple look angles to create a time series with temporal resolution on the order of days- to- weeks. Because the coherence maps reflect surface change and not deformation, comparison is not limited to common look-angles or ascending/descending orbital orientations, and temporal resolution finer than the orbital repeat period (usually about one month) is possible. A first test of this technique compares field-based geologic mapping with InSAR-derived coherence maps for the emplacement of the Campout lava flow at Kilauea Volcano, Hawai`i. The Campout flow originated as a breakout from the Prince Kuhio Kalaniana`ole lava tube in May 2006 (2). Flow margins were mapped using handheld GPS about every 1-2 weeks during mid-2006. Detailed maps of the advancing flow front are therefore available for comparison with lava flow maps derived from interferometric coherence. Preliminary results suggest excellent correspondence between the field- and coherence-based maps. Coherence-based lava flow maps are advantageous because they show the instantaneous configuration of the entire flow field, and can provide important information about lava flows that cannot be observed in the field owing to remote locations or hazardous conditions. (1) Zebker et al., 1996 (2) http://hvo.wr.usgs.gov/kilauea