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Scaling law between corner frequency and seismic moment of microearthquakes: Is the breakdown of the cube law a nature of earthquakes?
Author(s) -
Hiramatsu Yoshihiro,
Yamanaka Hiroshi,
Tadokoro Keiichi,
Nishigami Kin′ya,
Ohmi Shiro
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013894
Subject(s) - seismic moment , seismology , geology , borehole , cube root , scaling , sampling (signal processing) , waveform , induced seismicity , law , fault (geology) , physics , mathematics , geotechnical engineering , geometry , voltage , optics , quantum mechanics , detector , political science
The corner frequency, f C , and the seismic moment, M 0 , of microearthquakes (local magnitude from −1.3 to 1.3) are estimated from the records of sensors located at an 1800‐m‐deep borehole at the Nojima fault, central Japan. The digital waveforms of each event are recorded with two different sampling rates, 10 kHz and 100 Hz. The source parameters estimated from high‐sampling data satisfy a relationship of M 0 ∝ f C −3 , corresponding to a constant stress drop law, while those calculated from low‐sampling data follow a relationship of M 0 ∝ f C −4 . A lack of high frequency components in the 100 Hz sampling data seem to be obvious, indicating that the value of f C and M 0 are incorrectly estimated and the relationship of M 0 ∝ f C −4 is an artifact caused by the limited frequency band of these data. The scaling relationship of M 0 ∝ f C −3 is, thus, also valid for microearthquakes, and the breakdown of the constant stress drop law, reported in the literature, is not well founded.