Geoelectrical structure of the crust and upper mantle in the Xingtai earthquake area and its tectonic implications

Magnetotelluric (MT) sounding observations have been carried out along four profiles in the Xingtai earthquake area and its neighbouring regions. The results show characteristics of the geoelectrical structure of the crust and upper mantle for this region. The focal area looks like complex, while the surrounding area seems to be simple. The range of seismogenic depth is more complicated than the other depth range. Sharp changes of the electrical structure of the focal area indicate the hidden faults with steep angles. High conductive layers may represent the detachments of 10 9a 20km depth. Upper mantle uplift is likely associated with upward migration of mantle material. These features are of great importance to understanding the tectonic background of the study region, the seismogenic structure, and relation between shallow and deep structure.