Advances in Conception about Earthquakes - Earthquake Engineering for Structural Design - page 102

Chapter4

AdvancesinConceptionabout
Earthquakes

4.1FROMENGELADOSTOGPSSYSTEM

4.1.1Mythological Period

“…Greece is the Country where Philosophy, Democracy and Seismology were
born…” (Papazachos, 1994).

This sentence testifies that, where one of the oldest and most brilliant civilizations
was developed, the seismic activity was the highest in the whole of Europe.
Ancient Greek historians and geographers were among the first who made very
careful macro-seismic observations and ancient Greek philosophers were also
among the first who made interesting proposals for explaining the causes of
earthquake generation. The ideas of people in the pre-philosophical period (before
the 6

th

century BC ) for the causes of earthquake generation have had a mythological
character. Thus, according to the Greek and Roman traditions, Engelados , son of
Tartarus and Earth and leader of Geants, was buried in Sicily under Etna by the
goodness Athena, under the order of Zeus (Fig. 4.1). When Engelados moves and
sighs in his grave, earthquake and eruption from Mont Etna occur. In the Japanese
tradition it is believed that a monster Namazu (giant catfish) (Fig. 4.2) lives under
the islands of Japan and causes earthquakes. Namazu liked to play pranks and
could only be restrained by Kashima, a god who protected the Japanese people
from earthquakes. So long as Kashima kept a mighty rock with magical power over
the catfish, the Earth was still. But when he relaxed his guard, the catfish thrashed
around, causing earthquakes. In India, the idea was that the Earth is held up by
eight mighty elephants staying on the back of a turtle. When one of them grew
weary, it lowered and shook its head causing an earthquake. Similar mythological
explanations for earthquakes were present all over the world where these events
occurred (ERI, 2001).
It is very important to mention that the first record of an earthquake was made
in China in 1861 BC , carved into bamboo. A Chinese man named Zhang Heng, in
132 AD , more than 1700 years before Europeans, invented the first instrument
properly designed to detect earthquakes (Fig. 4.3) (Agnew, 2002). The scope of
this first seismograph was to detect as quickly as possible a strong earthquake, in
order to allow the emperor to send immediate aid to the injured population
(Wieland, 2001).