Non-volcanic tremor is my main focus of research these days. We installed 8 small-aperture seismic arrays in Cascadia, northern Washington, over the migration path of tremor during an episodic tremor and slip (ETS) event. The map shows the location of the arrays (red squares). The arrays recorded seismic data for more than a year, which includes an ETS in August 2010. One of the goals of this experiment is to determine the depth of tremor in this region. I have developed a technique (multi beam back projection) to image tremor source with high resolution. Initial results shows that the majority of the tremor is near the plate interface, and aligns parallel to it. This is a research very much in progress, and more results to come soon.