Scaling relationship between the duration and the amplitude of non-volcanic deep low-frequency tremors

金沢大学大学院自然科学研究科自然計測金沢大学理学部We investigate a duration-amplitude relation of non-volcanic deep low-frequency (DLF) tremors in the Tokai region, southwest Japan, to constrain the source process of the tremors. We apply two models to the distribution, one is an exponential model as a scale bound distribution and the other a power law model as a scale invariant distribution. The exponential model shows a better fit to the duration-amplitude distribution of the tremors than a power law model, implying that the DLF tremors are caused by a scale-bound source process. The source process of the DLF tremors, therefore, differs from those for earthquakes. We suggest that the non-volcanic DLF tremor is possibly caused by a fixed source dimension with variable excess pressure of fluid or variable stress drop. Copyright 2007 by the American Geophysical Union