The upper crust in the forearc of the Cascadia subduction zone hosts a complex network of faults that accommodate trench-parallel and trench-normal shortening due to oblique subduction and northward migration of the Oregon/Washington forearc block. Outside of the Seattle area, the seismic potential of major faults, as well as how they connect in a 3-D network, is poorly known. The trench-normal Doty fault, a major, north-dipping forearc fault crosses the I-5 corridor south of the Centralia-Chehalis urban area. Its length, orientation, and hypothesized total offset are comparable to the active Seattle fault, but it is unclear if the Doty fault poses a similar modern seismic hazard. We present preliminary results from the Chehalis Basin project (fieldwork summer 2018). We seek to define the Doty fault’s length, structure, dip, and linkages with smaller, likely transpressive faults to accommodate 3-D crustal deformation. We investigate possible blind faults south of the mapped Doty fault, near the site of a proposed flood-control water retention facility, and present evidence for recent fault activity. A multi-disciplinary approach is critical for regional investigations given dense foliage and glacial cover. Thus, we apply aeromagnetic and ground magnetic data, a regional gravity grid, high-resolution gravity lines, seismicity from a local broadband network, targeted geologic mapping, provenance characterization of Quaternary to Neogene sediments, dating, Lidar interpretation and field reconnaissance of geomorphic features to our research questions. The aeromagnetic data and prior geologic mapping suggest the Doty fault connects to unnamed NNW-striking faults to the west, and our new data will confirm or refute this hypothesis. Initial mapping and aeromagnetic interpretation suggest transpressive faults exist NNE of the Doty fault, which together bound a discrete region of uplift (Lincoln Creek uplift). There is little seismicity in the region recorded by the PNSN regional seismic network, and our PASSCAL array will help confirm the existence or absence of small, local earthquakes that could indicate neotectonic activity.