We will discuss results from recent broadband seismic array experiments in Mexico and Peru, analyses of California network data, and the geophysical problems we are attempting to address. A common theme is the role of water and how it affects lithospheric stresses, failure, and mantle flow. Concentrated free water may explain the bright spot under the San Gabriel Mountains, the San Andreas heat flow paradox, the temperature dependence of seismicity. Dehydration embrittlement may account for pore pressures necessary for deep earthquakes, also low viscosity in the mantle wedge giving rise to flat slab subduction.