Last July's tsunami in Papua New Guinea was as intense and catastrophic as news reports indicated, a scientific survey has found, and recommendations have been put forth to avert such a disaster in the future. The tsunami and the earthquake that generated it occurred July 17, 1998, and the International Tsunami Survey Team (ITST) began a weeklong investigation July 31. It was the ninth major tsunami and the most devastating the team has studied in the past 6 years. The team was able to precisely map the inundation and determine that media reports of extreme flows to fairly small sections of shoreline were accurate. Wave heights of 10 m were confirmed along a 25‐km stretch of coastline with maximum heights of 15 m and overland flow velocities of 15–20 m/s. Both are extreme measurements, given the moderate size of the earthquake and its aftershocks.The team noted that the force of a tsunami current on an object is roughly 1000 times that of a wind of the same speed.

Meteorological tsunamis are long-period waves that result from meteorologically driven disturbances. They are also generated by phase coupling with atmospheric gravity waves arising through powerful volcanic activity. The AD 1883 Krakatau eruption generated volcano-meteorological tsunamis that were recorded globally. Because of its extreme violence and energy release (≥150±50 megatons explosive yield), and by analogy with the Krakatau event, it is highly possible that the ignimbrite-emplacement phase of the c. ad 200 Taupo eruption of North Island, New Zealand, generated a similar volcano-meteorological tsunami that may have reached coastal areas worldwide. Tsunami deposits of identical age to the Taupo eruption occur in central coastal New Zealand and probably relate to that event; definitive evidence elsewhere has not yet been found. In theory, volcano-meteorological tsunamis are likely to be produced during comparable eruptive events at other explosive volcanoes, and thus represent an additional volcanic hazard at coastal sites far from source. We suggest that evidence for such tsunamis, both for marine and lacustrine environments, may be preserved in geological records, and that further work searching for this evidence using a facies approach is timely.

No abstract

No abstract

An extensive search of newspaper reports, archival material, and the literature has revealed that many more tsunamis have affected the New Zealand coast than hitherto realised. 32 tsunami events are listed, including their probability of occurrence, the maximum runup height, as well as the epicentre and Richter magnitude for those events associated with earthquakes.