Mr. Mautert on the Dynamics of Earthquakes. 83 
forced sea wave; the great sea wave; all originated at the same moment, or 
quam proxime so, by one impulse, and setting out together. The sound wave 
through the earth, and great earth wave or shock, arrive first, and are heard and 
felt on land, accompanied, as far as the beach, by the small sea wave, which I have 
called the forced sea wave; these are almost instantly succeeded by the sound 
wave through the sea; next arrive the aerial waves of sound, and continue to be 
heard for a longer or shorter time ; and lastly, after a comparatively long interval, 
the great sea wave rolls in upon the shore, and the earthquake is complete; so 
far as all the phenomena belonging to one shock are concerned, it has passed 
through one complete phase. These, however, are generally repeated, but with 
diminished energy, each renewed impulse at the origin of disturbance renewing 
the whole train of effects. 
I have only further to consider very briefly what will take place and be 
observable upon the shore when the origin of the shock is not under the ocean 
bed, but upon dry land, in the heart of a great continent, or anywhere far 
inland. 
Here, then, the great sea wave is entirely absent; it can have no existence. 
The sound wave through the earth arrives first at the shore, or other distant spot, 
accompanied by the great earth wave, or true shock, which dips under the sea, 
and finally is lost beneath the ocean bed, or emerges, if sufficiently powerful, and 
produces a shock upon the shores of distant countries. At the moment that the 
earth wave plunges below the sea, if the shore be a beach, or shelving, a small 
forced sea wave will be produced, and thus a small, sudden, apparent recession 
of the sea, and sudden advance above its former level, will be observable; in 
fact, this phenomenon will be precisely the same, mutatis mutandis, whether the 
producing earth wave, pass from seaward to landward, or vice versd, The 
forced sea wave will exactly keep pace with the movement of the great earth 
wave below, while the sea continues shallow, but as this deepens, and finally the 
earth wave gets beyond the edge of soundings, the forced sea wave will be no 
longer produced, and it will gradually subside and be lost. 
Shortly after the passage of the earth wave or true shock, the aerial wave 
of sound produced by the eruption, fracture, or other original disturbance, 
will also reach the shore, and, passing off to sea, will finally become inaudible. 
These are all the wave phenomena which can occur, in general, in an earthquake 
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