Before and after the Datong—Yanggao earthquake in October 1989, a high precision thermometer (resolution 0.0001°C) installed at the Sanmafang O(?) servatory, which is about 75 km from the epicenter, recorded a significant geothermal anomaly. The amplitude of the anomaly is 0.15℃ and the duration time is over 50 days.
1995 Northern Niigata Earthquake of M 6.0 and its buried earthquake fault imaged by the distributions of seismic intensity and thermal anomaly of groundwater ,Japan
This paper will narrate briefly the principle and its method of concretwork, which look for survey temperature of the infrared radiation in the surface soil of the underground thermal source and ullastrate with examples siluation of the actual use in underground thermal anomaly area.
By using some information such as heat flow values,geotemperature gradient and thermal spring,the thermal anomaly zones are divided in the upstream area of the Yellow River,and the relation among geotherm,structures and earthquakes is discussed.
The study of observation data of geothermal tests for six years show that the information of geothermal anomalies at observatory Baijiatuan is very large. The geothermal anomalies are well related to the earthquakes with M_L≥4.0 occurred within 200km. Theer was obvious geothermal amonaly of intermediate and short period and just forthcoming for Datong earthquake on Oct 18th, 1989.
On the other hand,deep circulating groundwater heated by rock temperature moves upward under certain geological conditions,causing local temperature rising of wall rock and the formation of geothermal anomalies at shallow depth and promoting the formation of geothermal resources.
Along this faulted zone,distribution of thermal springs and geothermal anomalies is as in group and zonation,and together with its southerm part,Yadong-Yangbajing-Naqu strike slip fault made up a SN faulted structure of heat conductivity and controlling earthquake in west China.
Geothermal anomaly as a physical phenomenon of an active and latent volcanic area would be well recognized, and abrupt geothermal anomaly should also be understood.
But then, except for this type of thermal source in the surface thermal field, there still exist a lot of noises in the area where the abrupt geothermal anomaly is generated.