Earthquake is a form of tectonic activity, an earthquake contains a lot of information, its frequency range is very wide. So far, the main frequency range of seismic records is below 100Hz, and the ultrahigh frequency seismic information got less attention by researchers. However, high frequency microseismicity can provide important information on micro-activities of fault. This paper introduces a new 100kHz ultrahigh frequency seismometer and its first application on high frequency microseismicity observation. The telemeter has been applied in Dali, Yunnan. Several high frequency microearthquakes were recorded and the corresponding earthquake location and spectral analysis were done. The results show that high frequency microearthquakes caused by crustal movement do exist and can be recorded by our telemeter. The recorded microearthquakes are of magnitudes between M_W=-3.0 and M_W=-1.0, maximum hypocentral distance up to 4.87km, dominant frequency ranging from 100Hz to 300Hz, and maximum frequency as high as 800Hz. It is possible that the ultrahigh frequency microseismicity observation(UFMO) will become a new approach to the study on the tectonic movement.

Compared with the strong noise background,intensity of efficient signal is very small when using thermal radiation to obtain the current tectonic activity. Increasing range of thermal radiation resulting from fault activity accords with dimension of inversion precision of thermal radiation of land surface,and information of fault activity is submerged by inversion error of thermal radiation of land surface. Besides,it is difficult to discriminate the information of fault activity when the data precision is high. This paper develops a new method,i.e. the Mean Grad Method (MGM),to solve the above-mentioned problems. First,we average the long-time data to gain a higher data precision at an expense of losing time information,then,distinguish the space distribution of the current tectonic activity from thermal radiation field of land surface by space grad of thermal radiation according to the difference between influence of atmosphere and tectonic activity on land surface. This method can offer some features on variation of current tectonic activity with time and space and is helpful for plotting out earthquake danger area.

For extracting the information about fault activity and seismicity from thermal infrared radiation,two crucial problems should be taken into consideration: 1) Aerosphere exists between solid earth and the satellite based sensor,and thus influences the infrared energy of land radiation when it passes through the aerosphere to arrive at the sensors. Moreover,the atmosphere itself is involved in thermal radiation,too. Therefore,to extract the geophysical information from thermal radiation,we have to begin with the estimation of atmospheric influence; 2) for identifying the anomalies induced by fault activity in thermal radiation,we should be able to distinguish the normal radiation from anomalous radiation,as anomaly can only be identified in reference with normality. This paper discusses these problems from the following aspects: 1) define the concepts of land surface brightness temperature (LSBT) and its annual variation field. LSBT would be an important physical concept in extracting the geophysical information from thermal radiation. LSBT should be assigned to the category of radiation energy of land surface,rather than the traditional "temperature" concept. Once the emissivity is known,the temperature can easily be calculated according to Planck law; 2) introduce the split window method for calculating the LSBT and the influence of atmosphere. The calculation shows that the influence of atmosphere on brightness temperature received by satellite based sensor is about ?10K; 3) the annual variation field of LSBT in China is extracted from the LSBT data by using the wavelet and split-window methods; the data used in this study come from the observations of NOAA/AVHRR from 1981 to 2001. The results of this study may provide a basis for further analyzing the anomaly field of thermal radiation.

After a series of complicated modifications the surface temperature of the Earth can be measured. Usually this surface temperature is referred to as land surface temperature. The heat effect that engenders this temperature variation may come from the climate and subsurface heat sources. Among them,the subsurface heat sources are of particular importance to earthquake and active fault studies. Unfortunately,the heat effect of climate is much larger than that of the subsurface heat sources so that it may conceal the information of subsurface thermal activity. Heat Penetrability Index (HPI) method is proposed in this paper for measuring subsurface thermal activity. The first assumption for HPI method is that the sun is heating the land surface synchronously. The second is the horizontal variation of heat exchange rates of rocks on top of subsurface heat sources. Provided that the rocks are heated,then the variation of surface temperature can be observed. According to the afore mentioned concepts and thermodynamics,the HPI can be deduced through correlation analysis as expressed by: where u and v represent surface temperature in two different areas,n is the sample number in the scanning window and D is the Heat Penetrability Index. When subsurface heating event takes place,D will go up,and vice versa. Some examples from experiment and satellite infrared image analysis are presented to test the effectiveness of HPI method.

The calculation of land surface temperature from thermal radiation requires the emissivity value of rock. However,there are lots of rocks in the Earth,and even the rocks of the same type may have obviously different emissivity. Recent methods for measuring the emissivity of rock are relatively complex,and most of them depend excessively on environmental condition. Therefore,when plenty of emissivity data are needed,it is necessary to develop a simple method of measurement. In fact,emissivity is a constant at room temperature,and the radiation of instrument itself and environment can enjoin the inversion as an unknown quantity. Then emissivity can be obtained by least square method through measuring the radiation of rock in a series of temperature and radiation conditions. On the basis of this method,the emissivities of 16 rock samples were measured. The square error of the results keeps in about 0.01,mostly less than 0.01,and the correlation coefficient of all linear fits is larger than 0.99.

The correlation between deformation and temperature is tested in detail on five rock types commonly observed on the Earth's surface. It is proven by both experimental and theoretical analysis that during the elastic deformation stage,the temperature of the rock is directly proportional to the loading force. According to the first and second laws of thermodynamics and Maxwells equation,the following relation can be deduced: σ-σ₀=-(cσρ)/α ln [T/T₀] or T/T₀= exp [-α/cσρ(σ-σ₀)] where σ is stress,T is temperature in Kelvin scale,α is modulus of heat strain,c σ is heat capacity and ρ is density. The results of the experiment are consistent with that of classic thermodynamics. Under Earth's surface condition,i.e. ordinary temperature and pressure,the maximum temperature increment of the sample elastically deformed in an open system is around 0.2K,and the normal rate of temperature rise is approximately 3mK/MPa. At the moment of fracturing,the temperature increment of the samples is much greater than that during elastic deformation,ranging from a couple degrees to more than ten degrees. The temperature increments caused by the elastic deformation of rocks are so minute that not only will they have any effect on climate,but cannot be identified by satellite infrared detectors. Therefore,new methods have to be explored for distilling faint information from infrared images,while the other thermo anomalies aside from elastic deformation should be carefully reviewed.

The infrared signals produced during rock deformation are very faint and tiny,so that the measurements of them require excellent capabilities of detection system and strict working environment. The reliability of the results of infrared experiment,therefore,depends greatly on the reasonable technical specifications of infrared photodetector,high sensitivity recorder for temperature field and effectively controlled thermal background. All of the key parameters are discussed in detail in this paper based on laboratory infrared observation. The features for an infrared camera include spectral band,digitizing resolution,view field etc. For capturing the optimal infrared images,it is suggested that the spectral range should be 7～13μm,the observation range should be from 0.5m to infinity,and high-density focal plane array should be employed as far as possible. In order to confirm the temperature from infrared image,a surface temperature recorder with multi thermometers should be employed as an eyewitness working alongside the camera. A realistic experiment system has been developed based on the afore mentioned discussion. Aside from the traditional functions of infrared camera,the system is fitted with high-speed data transmission component. The infrared focal plane array has 320×240 pixels,and 25 frames of temperature field data are saved into the hard disk per second. Some steel beam bending and steel cylinder compressing experiments were made for testing the system. The tests have proved that the system is reliable and the data quality is improved greatly.