In the meizoseismal area, many persons saw waves crossing the surface
of the ground. At Akasaka, according to one witness, the waves came
down the streets in lines, their height being perhaps one foot, and
their length between ten and thirty feet. To the north of the same
area, we are told that "the shoreline rose and fell, and with this
rising and falling the waters receded and advanced." Even at Tokio,
which is about 175 miles from the epicentre, the tilting of the ground
was very noticeable. After watching his seismographs for about two
minutes, Professor Milne next observed the water in an adjoining tank,
80 feet long and 28 feet wide, with nearly vertical sides. "At the
time it was holding about 17 feet of water, which was running across
its breadth, rising first on one side and then on the other to a
height of about two feet." Still clearer is the evidence of the
seismographs in the same city. Instead of a number of irregular waves,
all the records show a series of clean-cut curves. The heavy masses in
the horizontal pendulums were tilted instead of remaining as steady
points. They were not simply swinging, for the period of the
undulations differed from that of the seismograph when set swinging,
and also varied in successive undulations. It was ascertained
afterwards, by measurement with a level, that to produce these
deflections, the seismograph must have been tilted through an angle of
about one-third of a degree.
_Direction of the Shock._--Shortly after the earthquake, Professor
Omori travelled over the meizoseismal area and made a large number of
observations on the directions in which bodies were overturned, taking
care to include only those in which the direction of falling would not
be influenced by the form of the base, such as the cylindrical stone
lanterns so frequently found in Japanese gardens. At some places
these bodies fell in various directions, at others with considerable
uniformity in one direction. For instance, at Nagoya, out of 200 stone
lanterns with cylindrical stems, 119 fell between west and south, and
36 between east and north; the numbers falling within successive
angles of 15° being represented in Fig. 43. The mean direction of fall
is W. 30° S., coinciding with that in which the majority of the
lanterns were overturned. Similar observations were made at forty-two
other places within and near the meizoseismal area, and the resulting
mean direction for each such place in the Mino-Owari district is shown
by short lines in Fig. 44, the arrow indicating the direction towards
which the majority of bodies at a given place were overturned. It will
be seen from this map that the direction of the earthquake motion was
generally at right angles, or nearly so, to that of the neighbouring
part of the meizoseismal zone, and that on both sides of it, the
majority of overturned bodies at each place fell towards this zone.
[Illustration: FIG. 43.--Plan of Directions of Fall of Overturned
Bodies at Nagoya.]
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