Accuracy and Resolution of ALOS Interferometry: Vector Deformation Maps of the Father's Day Intrusion at Kilauea

David T. Sandwell, David Myer, Rob Mellors, Masanobu Shimada, Benjamin A. Brooks, & John Foster

Published November 2008, SCEC Contribution #1187

We assess the spatial resolution and phase noise of interferograms made from L-band ALOS SAR data and compare these results with corresponding C-band measurements from ERS. Based on cross-spectral analysis of phase gradients we find that the spatial resolution of ALOS interferograms is 1.3 times better than ERS interferograms. The phase noise of ALOS (i.e., line-of-sight (LOS) precision in the 100 m to 5000 m wavelength band) is 1.6 times worse than ERS (3.3 mm vs. 2.1 mm). In both cases the largest source of error is tropospheric phase delay. Vector deformation maps associated with the June 17, 2007 (Father's day) intrusion along the east rift zone of the Kilauea volcano were recovered using just 4 ALOS SAR images from two look directions. Comparisons with deformation vectors from 19 continuous GPS sites show rms line-of-site precision of 14 mm and an rms azimuth precision (flight direction) of 71 mm. This azimuth precision is at least 4 times better than corresponding measurements made at C-band. Phase coherence is high even in heavily vegetated areas in agreement with previous results. This improved coherence combined with similar or better accuracy and resolution suggests that L-band ALOS will outperform C-band ERS in the recovery of slow crustal deformation.

Citation
Sandwell, D. T., Myer, D., Mellors, R., Shimada, M., Brooks, B. A., & Foster, J. (2008). Accuracy and Resolution of ALOS Interferometry: Vector Deformation Maps of the Father's Day Intrusion at Kilauea. IEEE Transactions on Geoscience and Remote Sensing, 46(11), 3524-3534. doi: 10.1109/TGRS.2008.2000634.