Geoscience Reference
In-Depth Information
XI. Devastating
(b) Vital communications are destroyed. There are widespread fires. Reversed
flows of water wash away to sea vehicles and other objects. Large rocks of
different kinds are carried onshore from the sea-floor;
(c) Destructions of fifth degree in many brick buildings. Some concrete buildings
suffer damage of fourth degree, and many of third degree.
XII. Completely devastating
(c) Practically all brick buildings are wiped out. Most concrete buildings have
suffered destructions of degrees not lower than third.
1.4 Tsunami Warning Service: Principles and Methods
The extremely long and sad experience of Japan's population with many thousands
of lives lost to tsunamis and earthquakes is expressed in the short inscription on
the stone stellae often found near the coastline. The hieroglyphs on the stellae say
the following:
Don't forget about earthquakes. If you feel an earthquake, don't forget about
tsunamis. If you see a tsunami, run up a high slope.
The following legend is told by the inhabitants of the city of Wakayama, situated
not far from Kyoto, the former capital of Japan and a most beautiful city. The ma-
jor of Wakayama once felt an earthquake. He understood he had no time to warn
the people on the shore of the tsunami danger, so he run-up the slope to the rice
fields, where the rice had been harvested, and set the granaries on fire. People, see-
ing the burning supplies of rice, hurried up to put the fire out and, thus, they happily
evaded the lethal strike of the tsunami wave against the coast. The grateful inhabi-
tants of the city erected a monument to the wise ruler.
By the 1960s many countries of the Pacific region had organized national tsunami
warning systems. The tsunami service organizations include a whole network of
seismic and hydrometeorological stations, special systems for operative alert trans-
mission, administrative organs for adopting resolutions and regional organizations
for implementing evacuation plans of the population.
In past years the work of a tsunami warning service (TWS) was based on routine
and/or urgent dispatches from operators on duty at seismic stations with round-
the-clock tsunami services. If a nearby strong earthquake (of magnitude
M
>
7) is
registered, the operator had, within 10 min, to determine the distance to its epi-
centre, the earthquake's magnitude and the approximate region of its location. The
operator had, then, to transmit the signal 'TSUNAMI warning' to the administrative
organ, to the tsunami headquarters and to the meteostation. The oceanology on duty
at the meteostation applied additional information to decide whether to announce
the warning or not. The all-clear signal was announced by the tsunami headquarters
upon agreement with specialists.
