IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS008 Poster presentation 2007
HRT wave precursor to the Sumatra earthquake
Dr. Wei Qian
Dept. of Physics University of Toronto IASPEI
Four PS100, which is a newly developed anti-interference high-precision geoelectric measurement
system, stations in Sichuan and Yunnan, China have recorded the harmonic resonance waves of
geoelectricity driven by tidal forces(HRT wave) precursor to the Mw 9.0 Sumatra earthquake. At
resonance T=T0, where the wattles component of the impedance is equal to zero, the RT wave peak
will be very large, sharp and an earthquake is impendent within 1-3 days. As preliminarily estimated,
the phase velocity of the RT longitudinal waves was Vl≈307km/h, and the vireual wave velocity
Vv=(VlVt)/(Vl-Vt) was 207 km/h. Hence, as long as the arrival time difference of the 2 RT waves at one
station is known, it is possibl to calculate the epicentral distance of a coming earthquake quantitatively.
For the earthquake, the free period of oscillation was T0=4~5h, from which the magnitude of the
coming earthquake can be determined. Both the arrival time difference and the virtual wave velocity
during and before the earthquake are almost equal to each other, the RT waves during the earthquake
were emitted by the fault failure, and the RT waves appearing 2 days before the earthquake were
emitted by the early failure of the fault in the hypocenter region of the earthquake. If we have a
reasonably designed the PS100 network, it will be possible to quantitatively predict the three factors of
a coming earthquake. Since the 1966 M 7.2 Xingtai earthquake, permanent observatories have been set
up in some of the major earthquake zones in China to investigate earthquake precursor of geoelectric
resistivity and current field. Precursors to the 1976 M 7.8 Tangshan earthquake has been found, e.g.
decrease of geoelectric resistivity, geo-resistivity impulse related to tidal force M2 wave, and geocurrent
filed changes related to tidal force MSf. A model of short-term earthquake precursor of tidal
force has been established in accordance. The PS100 anti-interference high-precision geoelectric
measurement system has been developed to overcome the instability of electrode polarization, the
interference of the natural electromagnetic field, and especially the interference of random current due
to industrialization, which will prevail on the globe. This system utilizes the Code Division Multiple
Access (CDMA) technique and the concept of black box to geoelectric measurement instrument. It
applies convolution and deconvolution to the encoded input time series and the observed output time
series, and identifies the true value of geo-resistivity with eliminated electromagnetic interference.
Specification tests have been conducted by China National Institute of Metrology regarding the antiinterference
ability of the PS100 system. A PS100 system had measured the resistivity of a 0.01%
measuring resistance, on which interference voltage from a signal generator (as source of the
interference) was applied. The results indicate that when the signal-to- noise ratio was between 20dB
and 0dB, both the difference between the detected and true values and the standard deviation of
multiple measurements were better than 0.1% (between 0.01% at 20dB and 0.1% at 0dB).
Keywords: earthquake precursors, geo electricity, pore fluids movement