A Study On The Anomalous Characteristics Of Earthquake Underground Fluids In The Southern Ordos Block Margin And Its Surrounding Regions

Earthquake underground fluids observation is a means in order to retrieve earthquake anomaly information. The experience of many years’ observation show that the records of underground fluids are unavoidably affected by many factors. Furthermore, the effect degree are also not the same due to the differences of observation sites’ conditions. Underground fluids observation not only record the seismic information, but also are unavoidably contaminated by non-earthquake events induced by the meteorological and anthropogenic factors. For example, barometric pressure, precipitation, pumping, injection and loading so on. And these influence factors can arouse the physico-chemical properties changes. So studying all kinds of influence factor of earthquake underground fluids observation and knowing of their relationship not only have great importance to identify and retrieve earthquake precursor information, but also can assist us in understanding the aquifer characteristics.This paper systematic describes the fundamental analyzing methods of underground fluids, and the methods for excluding typical disturbance events of the southern Ordos block and its surrounding regions. After the deep analysis on the influences of precipitation, loading, barometric pressure on the underground fluids, we extracted the information of earthquake precursor. Meanwhile, we systemically concluded the anomalous spatial-temporal characteristics of fluids prior to earthquakes over the past three decades in the southern Ordos block margin and its surrounding regions(mainly including the Shanxi Graben and northeastern margin of the Tibetan Plateau), this study will contribute to earthquake forecasting.