Exploiting ALOS observations as a guide to what will be possible with DESDynI

Over the last several years, L-band radar observations from the Japanese ALOS satellite has allowed a variety of crustal deformation studies that give us a taste of what will be possible with a dedicated L-band InSAR mission such as that currently being planned by NASA. Here we illustrate the success (and sometimes failure) of ALOS PALSAR data to measure ground deformation associated with large earthquakes (2010 Mw 8.8, Maule, Chile and 2011 Mw 9.0 Tohoku-oki, Japan), volcano deformation in forested or jungled areas (Java), small earthquakes (aftershocks of the Tohoku-oki earthquake), interseismic deformation (the San Andreas and Hayward faults in California), and glacier flow on a temperate ice cap (Hofsjokull, Iceland). In several of these cases, we use time series methods, primarily the MInTS approach, to detect smaller amplitude signals and to separate out the effects of seasonal and tectonic deformation while also mitigating the effects of propagation delays accrued in the atmosphere. All data for these studies were made available through USGRC acquired through the Americas ALOS Data Node (AADN) located at the ASF. In addition to deformation analysis, we look at the behavior of interferometric correlation at L-band as a function of orbital and temporal baselines. In vegetated areas such as Java, we find that observations need to be consistently made at shortest time intervals possible (45-90 days) if correlation is to be reliably maintained. Short time intervals are also required to increase sensitivity to small amplitude signals, minimize trade-offs between the estimates of coseismic, post-seismic and seasonal processes, and to reduce the potential impact of transient decorrelation events (e.g., rainfall). We also highlight the importance of short repeat times to enable the use of decorrelation for rapid damage assessment after catastrophic events.