Dynamic evolution patterns of the degree of ground resistivity anisotropy and the seismogenic process

Abstract

Following a new train of thinking, this paper has explored first the potential information in the ground resistivity data observed by the existing geoelectric observation system, investigated and proposed a new dimensionless geoelectric precursor factor, the degree of ground resistivity anisotropy, S, and studied the characteristics of dynamic evolution pattern of S during the seismogenic process. The results show that, during the seismogenic process, the degree of ground resistivity anisotropy (S) displays a process of "normal" -~ "abnormal strengthening (amplitude, range)" ~ "abnormal weakening"~ "earthquake occurrence" ~ "normal". The earthquake would occur at the time when the S value has entered the late stage of strengthening and turns to weaken and in the gradient belt on the margin of S anomaly region. The dynamic evolution pattern of S reflects the changes of the tectonic stress field during the seismogenic process. Therefore, it would be possible to trace the process of earthquake generation and occurrence from the dynamic evolution pattern of S so as to service earthquake prediction.Key words: degree of ground resistivity anisotropy dynamic evolution pattern seismogenic process

Experimental Studies on the Changes in Resistivity and Its Anisotropy Using Electrical Resistivity Tomography

“…Our results indicate that λ * and α do not change outstandingly with the increase of pressure at a certain depth. However, the striking changes in apparent resistivity anisotropy were observed before earthquake [7,8,38]. We thought that we did not use water-saturated samples while the underground rocks are often in saturation because of the presence of rich groundwater.…”

“…Studies on resistivity anisotropy require that resistivity measurements are conducted along at least two measuring lines arranged in different directions and that they must intersect at a point. For example, Mao et al [7,8] used the resistivity data measured along E-W and N-S trending measuring lines in studying the changes in the degree of earth resistivity anisotropy during the course of earthquake preparation. Chen et al [22][23][24][25] designed four measuring lines in studying the changes of apparent resistivity anisotropy in lab.…”

“…The striking changes in electrical resistivity and its anisotropy were widely observed before earthquake, mine earthquake, volcanic activities, and geologic motions [1][2][3][4][5][6][7][8][9][10][11][12]. In order to address the change characteristics of resistivity and its anisotropy, many investigators conducted a plenty of experiments on rock samples under compression and during fracture, shear, and frictional sliding in lab [13][14][15][16][17][18][19][20][21][22][23][24][25] and theoretic studies [26][27][28][29][30].…”