Abstract
The energy of earthquakes may be considered as the change of the interior heat of the earth, though the exact mechanism is not yet known, and in a sense, it is mechanical action of the earth heat engine. The efficiency of such an engine was calculated, and is found that it is given by The numerical value of the efficiency is about 10-3, and hence it is seen that its efficiency is very low. On the other hand, the mean energy of earthquakes which occur in every year on the whole earth is about 102_??_ ergs and the energy loss due to the heat conduction in the earth's crust is about 2×1027 erg/year, hence the efficiency must be 1024/2×1027=0.5×10-3 which agree with the theoretical value at least in its magnitude. The discrepancy between them seems to be due to the assumption made in the calculation that the effect of friction may be neglected.
