- Tom Pierson has been a research scientist at the USGS Cascades Volcano Observatory (USGS CVO) since 1981. His field-based research focuses primarily on the hydrological response to volcanic eruptions—lahars, debris avalanches, and floods. Pierson spoke to GSOC in February 2014 about the debris flows following the eruption of the Chaiten Volcano in Chile. Pierson’s April 2018 topic hit a lot closer to home, although the Pacific Northwest also has plenty of volcano hazards.