Large tectonic earthquakes may trigger other phenomena such as volcanic eruptions and edifice collapse, and such events in coastal areas can generate tsunamis. When closely spaced in time, these events can combine their effects to cause more serious and variable consequences than anticipated from volcanic or seismic hazards forecast separately. The Kamchatka volcanic arc, because it has been affected in the recent past by such events, provides an invaluable natural laboratory for understanding these phenomena.An international team recently studied the strong events (Mw ˜ 5.5) that have occurred in Kamchatka over the last 10 k.y. The work was organized within the framework of a new NATO-Russia collaborative project studying major events occurring in volcanic arcs. It follows a joint U.S-Russian investigation carried out during 2000--2002 under the umbrella of the National Geographic Society, the U.S. National Science Foundation, and the Russian Foundation for Basic Research, which combined volcanic, geochemical, and geophysical evidence of catastrophic geological events. This work is now being built on by providing the field data necessary to understand the age, magnitude, and recurrence intervals of paleo-earthquakes, and the location, geometry, and kinematics of the main active crustal faults. Improvements in the understanding of the age and size of Holocene eruptions and refinement of their ash dispersal patterns are also being made. A multidisciplinary team is involved in this work, as well as similar studies in the Aeolian volcanic arc in Italy, thus allowing the results to be combined and compared to arrive at more general perspectives.