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Rabaul

Among large calderas, Rabaul in Papua New Guinea has a modern record of precursory unrest that exceptionally includes both eruptive and non-eruptive crises.

 

Unrest and recent activity

Between 1971 and 1994, unrest was characterised by rates of surface uplift and volcano-tectonic (VT) seismicity that changed unevenly with time by an order of magnitude. Although the VT event rate and uplift rate peaked in 1983-1985, eruptions only began a decade later, on 19 September 1994, and followed just 27 hours of anomalous changes in precursory signal. 

Even though short-term emergencies at large calderas tend to be evaluated independently as regards the probability of eruption, it has long been recognised that they may belong to longer-term unrest that will trigger an eruption only when a cumulative threshold has been exceeded. However, the connection between long-term unrest and eruption potential has been described only qualitatively. The precursory behaviour at Rabaul provides an outstanding opportunity to establish whether the potential for eruption can be quantified using long-term changes in caldera unrest.
 

Volcanic hazards

Although located within a remote region of Papua New Guinea, hazards from eruptions are substantial. An eruption in 1994 destroyed the town of Papua (see USGS for more information). Eruptions can also produce hazardous ash that can disrupt air traffic within the surrounding areas.


Resources

Researchers: Christopher Kilburn, Robert Robertson

Related Hazard Centre publications:

 Deformation regime and long-term precursors to eruption at large calderas: Rabaul, Papua New Guinea. Earth Planet Sci Lett, 438, doi 10.1016j.epsl.2016.01.003.