This study attempts to acquire information on tectonic activity in western China from land surface temperature (LST ) field data. On the basis of the established relationship between heat and strain, we analyzed the LST distribution in western China using the satellite data product MODIS/Terra. Our results show that: 1. There are departures from annual changes of LST in some areas, and that these changes are associated with the activity of some active tectonic zones. 2. When annual-change background values caused by climate factors are removed, the long-period component (LST LOW ) of temperature residual (DT ) of the LST is able to serve as an indicator for tectonic activity. We have found that a major earthquake can produce different effects on the LST fields of surrounding areas. These effects are characterized by both rises and drops in temperature. For example, there was a noteworthy temperature decline associated with the Sumatran M9 earthquake of 2004 in the Bayan Har-Songpan block of central Tibetan Plateau. 3. On the other hand, the LST field of a single area may respond differently to major shocks occurring in different areas in the regions surrounding China. For instance, the Kunlun M 8.1 event made the LST on the Longmen Mountains fault zone increase, whereas the Zaisan Lake M 7.9 quake of 2003, and the Sumatran M 9 event of 2004, caused decreases in the same area's LST. 4. The variations of land surface temperature (LST ) over time are different in different tectonic areas. These phenomena may provide clues for the study of tectonic deformation processes. On the basis of these phenomena, we use a combination of temperature data obtained at varied depths, regional seismicity and strain results obtained with GPS Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Geoscience Frontiers (2010) 1, 57e67 measurements, to test the information related to tectonic activity derived from variations of the LST field, and discuss its implications to the creation of models of regional tectonic deformation. ª
The satellite thermal infrared remote sensing is attracting more and more attention in earthquake science, for satellite remote sensing has a significant advantage of the space information. However, there exist many key basic problems which should be delt with. For instance, what data should be suitably chosen in earthquake research? In this paper, the relationship between land surface temperatures obtained by field measurement and satellite remote sensing is studied, based on data from March, 2006 to February, 2008. Our results indicate that: (1) as for the two kinds of land surface temperatures, the difference at night is smaller than that of day, and the correlation at night is more significant than that of day; (2) No matter whether it is day or night, the correlation between long period components of the two kinds of land surface temperatures is more significant than that of short period, which implies that there exists rarely difference between day and night when the long period component is considered. These mentioned‐above analyses are helpful to select the data that we want.
Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics experiment with medium-scale samples, we have studied the effect of fault jogs, the most common irregularity along fault zones, on frictional behavior. The research indicates that extensional fault jog can be easily fractured because of its low strength and the fractured jog has no obvious resistance to fault sliding, and the micro-fractures occurring in the jog are indicative of stick-slip along the faults. The fault zone containing extensional jogs is characterized by velocity weakening and can be described by rate and state friction law. Compressional fault jog makes fault sliding more difficult because of its high fracturing strength, but the micro-fractures occurring in the tensile areas around fault ends at higher stress level can provide necessary condition for occurrence of stick-slip along the faults before the jog is fractured and thus act as precursors of fault instability. Compression jog can be taken as a stable indicator of fault segmentation until the jog is completely fractured and two faults are linked. en-echelon faults, extensional jog, compression jog, micro-fracture, stick-slip
The use of satellite thermal infrared information is being developed as a method of exploring current tectonic activity. To realize real world application, an objective, stable and testable thermal physical index that is simultaneously related with tectonic activity must be established. From the viewpoint of the energy balance, the land surface is a boundary where energy is exchanged between outer space and the solid Earth. Regardless of how complex the influencing factors are, the land surface is mainly affected by the Sun, atmosphere and underground heat. In this paper, first, the relationships among land surface temperature, solar radiation, atmospheric temperature and thermal information from underground are obtained employing a mathematic physical method based on the equation of heat conduction and energy balance at the land surface. Second, a thermal physical index called the geothermal flux index (GFI), which can provide the activity state of underground heat, is constructed. Third, the theoretical basis of the thermal physical index is verified using stable annual variations in land surface temperature and solar radiation. Finally, combined with known crustal deformations derived using a global positioning system, the effectiveness of the GFI in extracting field tectonic motion is tested. The results indicate that the GFI is effective in providing information on current tectonic activity. current tectonic activity, thermal physical index, geothermal flux index, remote sensing Citation: Chen S Y, Ma J, Liu P X, et al. A thermal physical index to explore current tectonic activity with satellite remote sensing.The use of satellite thermal infrared information to explore current tectonic activity is a relatively new concept [1], and its implementation faces many difficulties. Current research indicates that the thermal field is strongly related to stress-strain in time and space, and that the mechanism of temperature change differs in different stages of deformation and the distribution mode of a thermal image varies with the deformation. In the stage of elastic deformation, the temperature increment is positively correlated with variation in the volume strain. Pure shear deformation does not contribute to temperature variation. Specifically, shape change in the specimen does not lead to temperature variation. The temperature rises when the specimen is in a compressive state whereas the temperature drops when it is in a tensile state. This is to say, it is possible to judge whether a fault is active or not by detecting temperature change in a typical tectonic zone on the basis of the mentioned-above relationship between stress-strain and temperature variation [2][3][4][5]. However, information of tectonic activity under the surface and exterior factors, such as solar radiation, need be considered when using land surface temperature to judge current fault activity. Addressing the problem that the signal of the valid information is much weaker than background signals, we highlight information of current tectoni...
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