IUGG2003 Sapporo, Japan　Poster session
・JWS01 Is Short-term Earthquake Prediction Possible?

ANOMALOUS PHENOMENA APPEARED SYNCHRONISTICALLY BEFORE 1993 SW-OFF HOKKAIDO EARTHQUAKE IN JAPAN

                                                    Author: Hideo TORIYAMA(*1)
                Co-author: Shin'ichi UDA(*2), Yoshiharu SAITO(*3)
                                                      Presenter: Yoshiharu SAITO
*1 International Study Center "Before Day" Tokyo Branch
*2 Registered Engineer's Office "Network the Earth"
*3 NEC Engineering, Ltd.

    Under normal conditions, tree potential whose measuring system is shown in Fig1 shows certain patterns. Preceding earthquakes of magnitude 7 or above, anomalous potential changes were often observed throughout the period June 1977 to June 2003.
    In the case of an Ulmus kaeki tree which had been growing naturally and had reached the age of forty years, dramatic anomalous potential appeared during the period 17 days to 4 hours prior to a strong earthquake (M:7.8) which occurred on July 12 at 22:17(JST), 1993 at southwest Hokkaido, northern Japan (Fig.2).
    From early June through June 24, 1993, the potential of the Ulmus tree indicated normal trends (Fig.3-1). However, anomalous potentials were observed from 20h on June 25 through 5h on July 13 (Fig.3-2, Fig4, Fig5, Fig6, Fig.7-19). In the meantime the strong earthquake (M:7.8) occurred. It must be mentioned here that the anomalous potential assumed five times changing patterns during June 25 to July 12 in the anomalous period (Fig.8). These facts suggest that the precursory process change successively five times (Fig.9).
    A feeling for the extent to which tree roots penetrate and explore the soil can be gained from the fact that total root length of an individual tree must be measured in kilometers, and number of root hair can be counted in millions or billions. As a result, a huge total surface area of tree roots contact a vast number of soil particles which are closely related to soil water and groundwater. Accordingly, it is entirely fair to say that the tree is closely connected with the earth.
    Soil is a well-developed system of inorganic material which contains silicates and organic substances. We must notice that the physical properties of soil include properties as a powder and also electrochemical properties in the soil-water layer.
    Ulmus tree roots in particular extend very deeply into the ground and spread like a network in three dimensions. In general, one of the characteristics of a "living root system - hydrated soil - hydrated cracks of rock" structure is that it sustains a chain of electromagnetic conductivity. This likely makes it possible for the living tree to receive stimuli consisting of geoelectrical, geomagnetic, and geoelectrochemical factors which implies existence of precursory phenomena of earthquakes.