Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

His to ric al Mate ria Is of Chine s e Ea r t h quake s1631. IntroductionHistorical materials are indispensable for tlie prolongation of time span in thestudy of seismicity. In this paper, instrumental data, as well as historical records,are included. The historical documents in China are investigated. Tlie compilationof historical materials is described. The use of them in the late decades is brieflyreviewed. Finally, the unification of magnitude scale for instrumentally determinedearthquakes of the 20th century arid the method to be used for the seismologicalanalysis of macroseismic records of historical earthquakes are given.2. Historical Documents in ChinaScience and culture developed early in China, and we have long recorded history.It was in the 2nd century B.C. that Chang Heng invented the first seismoscopeof the world. Since the appointment of an official liistorirtri in the Ying dynasty(13-11th century B.C.), not only political affairs, but also such natural phenomenaas astronomical, meteorological and seismological events were recorded. Theinvention of printing around the 10th century greatly facilitated tlie preservationof historical materials. After the Yuan dynasty, i.e., since the 14th century, localrecords or annals of different provinces, districts and counties became popular.Thus, the seismological niaterials increased greatly both in number and in contents.Ancient Chinese usually correlated natural phenomena with social and politicalaffairs. The occurrence of rare natural phenomena, such as earthquakes, comets,etc., and the appearance of rare animals and plants such as phoenix, glossy garnoderrna,etc. were considered to be auspicious sign or ill omen. Under the control ofsuch thought of “God’s will”, the emperor required the officials of the central government,as well as tlie local authorities to report such things, officials and peoplepaid attention to and recorded them in different ways and by different. means. Asa result, some of them were handed down till now.Which item of our recorded historical earthquakes is the first reliable one isa debatable problem. “Taiping Yu Lan” quoted an item from the classic “Motze”:“While the San-Miao was going to be destroyed, the Earth quaked, fountainssprang”. This is a tale of about 2221 B.C., before the invention of Chinese charactersin the Sliang Dynasty (16-11th century B.C.). The classic “Mo-tze” was written intlie 4th century B.C., it only recorded legends popular at that tinie. Therefore, it isconsidered to be riot very reliable. Nevertheless it seems to be the earliest writtendescription of an earthquake in the world. Another classic “Chronicle on Bamboo”inscribed on bamboo at the time of the Warring States (5th-3rd century B.C.)recorded: “In the 35th year of Emperor Shun (about 1831 B.C.) Mount Taishanquaked”; ‘‘In the 10th year of Emperor Jie of Xia Dynasty (about 17G7 B.C.) fivestars ran out of orbits, stars fall like rain, the Earth quaked, Rivers Yihe and Luolieexhausted”; arid “In June, the third year of Emperor Yi of Shnng Dynasty (about1189 B.C.), Zhou (northeast of Qishan in Shaanxi Province) quaked”. As the historybefore Sliang Dynasty is riot well known, these items are also aiicient legends.The “Lu’s Chronicle” written in 239 B.C. recorded: “In June, the 8th year ofEmperor Wen-wang of Zliou Dynasty (about 1177 B.C.), tlie Emperor sickened for5 days and the Earth quaked in the whole couiitry”. Some historians claim thatit was written less than a thousand years after the event, at a time before theburning of still earlier books by the first Emperor of Qin Dynasty in 212 B.C.,