We are running an Array of Arrays (AofA) experiment to study tremor with unprecedented resolution in an active and relatively predictable portion of the Cascadia SZ. Our plan has two field seasons of temporary seismic deployments, augmented by an inexpensive extension of the already successful CAFE experiment. The first year, the temporary deployment will embed about 350 sensors, half vertical and half horizontal, with a quarter in a central dense array and the rest in up to six satellite arrays, to catch the expected mid-summer 2009 ETS episode. The second year, we will strive to re-capture interesting patterns to measure the degree to which ETS repeats in detail, plus add L-shaped long, dense, linear arrays for extra resolution.
The AofA will enable specialized array processing techniques such as high-resolution beamforming and spectrograms, which we demonstrated in an 84-station pilot experiment this past spring, to pinpoint tremor and LFE location and character in space and time. We expect to study the location and depth of tremor, its migration, its spectral content at high frequencies, as well as better resolution of source spectra from earthquakes through LFEs to tremor. Analysis of the data from this unique array will answer many key questions about tremor and further elucidate the physics of the ETS process.