Vailulu’u seamount is an active underwater volcano that marks the end of the Samoan hotspot trail (Hart et al., 2000). Vailulu’u has a simple conical morphology (Figure 1) with a largely enclosed volcanic crater at relatively shallow water depths, ranging from 590 m (highest point on the crater rim) to 1050 m (crater floor). The crater hosts a 300-m-high central volcanic cone, Nafanua, that was formed between 2001 and 2004. Seismic activity at Vailulu’u included a series of globally recorded magnitude 4.1–4.9 earthquakes in 1973 and 1995, and substantial volcano-tectonic activity recorded over 45 days in 2000, with an average of four earthquakes per day and a maximum of 40 per day (Konter et al., 2004). Hypocenter locations are located directly below the major hydrothermal vent areas (Staudigel et al., 2006).