Timing the wave
The lifestyle in the villages around the lagoon had many charms especially when
compared with the lives we lead in the cities. Apart from getting the kids to
school, there were few schedules to keep, no PMVs to catch, no power cuts (no
power!), no pokies, no raskols.
Watches and clocks were put to one side and the honoured civil service custom of
clock-watching became a forgotten art. Ah, paradise.
However, the relaxed attitiude towards time keeping has disadvantages for any
poor fool of a outsider who comes around asking questions about the exact
timing of a natural event such as an earthquake or tsunami.
He is likely to get all sorts of answers. Some will tell him the 17 July
tsunami happened at 5.30, others 7.30 pm, and most others somewhere in the
middle at around 6.30 or 7 pm.
Fortunately for the befuddled questioner the world's earthquake recording
laboratories are quite obsessed about accurately recording the time and so
can tell him what time the earthquakes occurred, to the very second.
He, in turn, can use this information to pin down the timing of other events
such as the the tsunami. This is what today's story is about.
On the evening of 17 July seismologists recorded two earthquakes that
originated in the Sissano area. The earthquakes were 20 minutes apart, one
at 6.49 pm and the other at 7.09 pm, and the first was said to be the
stronger and hence the most likely to have triggered the tsunami. Let's call
the first EQ1 and the second EQ2.
Armed with this information one can then go and ask people in the Sissano
Aitape area such questions as how many earthquakes did they feel, which was
more strongly felt, and when did the wave arrive, relative to the earthquakes?
Another good question is whether the wave arrived square on to the shoreline,
or whether it came in obliquely, sweeping along the beach from left to right
or right to left. One can confirm this by looking at the debris paths that
the waves have left.
We can also look at damage and observe that the wave was at its most powerful
in the area from beyond Arop Community School in the east to Nimas village in
the west (labelled "devastated" on the map).