At least four seismic events have occurred at Mount Cayley since 1985 and is the only volcano that has recorded seismic activity in the field. This suggests that the volcano still contains an active magma system, indicating the possibility of future eruptive activity. Although the available data does not allow a clear conclusion, this observation indicates that some volcanoes in the Mount Cayley field may be active, with significant potential hazards. This seismic activity correlates both with some of Canada's most youthful volcanoes and with long-lived volcanoes with a history of significant explosive activity, such as Mount Cayley. Recent seismic imaging from Natural Resources Canada employees supported lithoprobe studies in the region of Mount Cayley that created a large reflector interpreted to be a pool of molten rock roughly below the surface. It is estimated to be long and wide with a thickness of less than . The reflector is understood to be a sill complex associated with the formation of Mount Cayley. However, the available data does not rule out the probability of it being a body of molten rock created by dehydrating of the subducted Juan de Fuca Plate. It is located just beneath the weak lithosphere like those found under subduction zone volcanoes in Japan.