Geoscience Reference
In-Depth Information
Table 6.4 Earthquake-generated tsunamis
(run-up heights and deaths)
Year
Site
Height
Deaths
2004
Banda Aceh
+30 m
100 000
1896
Japan
29 m
27 000
1992
Indonesia
26 m
1000
1933
Japan
20 m
3000
1946
Alaska
15 m
175
1993
Japan
11 m
175
1755
Portugal
10 m
30 000
1960
Chile
10 m
+1250
1992
Nicaragua
10 m
+150
1964
Alaska
6 m
125
From Abbott ( 1999 ).
Tsunamis also resonate in harbours when the wave period of the tsunami is a
harmonic of the natural frequencies of that harbour or bay. This can result in
theamplitude of the tsunami increasing greatly over time (Bryant, 2005).
Earthquake prediction
Earthquake prediction is not an exact science. However, progress is
being made in short-term predictions of earthquake activity. Approximately
3months after the Boxing Day (2004) earthquake and tsunami in Sumatra
another large earthquake (magnitude 8.7) occurred 200 km south near the Island
of Nias, Sumatra. This earthquake was predicted only 2 weeks before it occurred
by McCloskey et al .(2005). They calculated the stress imparted by the 2004 Boxing
Day earthquake onto nearby structures and faults and identified two main zones
that could experience an earthquake. One was the onshore Sumatra fault that
runs through the Island of Sumatra. The other at risk zone was the offshore seg-
ment of the subduction zone and it was here where the March 2005 earthquake
occurred.
Other studies have also presented methods to make short-term predictions
of earthquake activity. McGuire et al .(2005)compared foreshock to aftershock
activity on East Pacific rise transform faults. Through a retrospective study of
past earthquakes they developed a model which can be used to monitor fore-
shock activity and predict approximately when and where a major earthquake
may occur. There have been a number of reports of unusual animal behavi-
our in the days prior to earthquakes. It is not known why animals seem able to
Search WWH ::




Custom Search