Factors that provide protection - general
The story at Sissano mission was repeated at other Sissano villages. In some places everything was destroyed but in others houses survived intact. Only at Warapu was demolition complete.
Why was this so? What were the factors that saved some areas and not others?
If we can find the answers to these questions then we are part way towards reducing the risk from future tsunamis not only here in the Aitape district but also in other coastal villages in PNG and the southwest Pacific.
There are some obvious and long recognized factors. For example, offshore islands and reefs help protect the coastline by dispersing the energy of the wave.
Also, if the sea floor slopes steeply from the coastline the wave will not form a giant breaking wave but rather will arrive in the less destructive form of a rise and fall in sea level.
Another factor is that if villages are on high ground or are some distance from the water's edge then they are unlikely to be badly affected by the wave.
This is old stuff and obvious. From the evidence at Sissano what can we say that is new?