State of stress in the near-surface of the earth's crust

1992 ◽  
Vol 138 (2) ◽  
pp. 207-228 ◽  
Author(s):  
W. Z. Savage ◽  
H. S. Swolfs ◽  
B. Amadei

1982 ◽  
Vol 72 (5) ◽  
pp. 1707-1715
Author(s):  
Frand Wyatt ◽  
Kent Beckstrom ◽  
Jon Berger

abstract An instrument has been developed to monitor the horizontal displacement of near-surface monuments, so as to reduce the noise of observatory-based strain measurements. The device measures the shear strain in the upper 24 m of the earth's crust using an equal path length Michelson interferometer. The magnitude of the observations (∼50 μm) indicates that such measurements are needed to interpret the records produced by precision strainmeters.


2018 ◽  
Vol 56 ◽  
pp. 04019
Author(s):  
Nikolay Grib ◽  
Valery Imaev ◽  
Galina Grib ◽  
Lyudmila Imaeva ◽  
Igor Kolodeznikov

Impulse loads, arising due to the high natural seismicity of the South Yakutia region, exercise both direct and indirect effects on the upper part of the Earth's crust during industrial explosions. The direct effects result from nonlinear displacements caused by the blast wave and the subsequent formation of new disturbances. The indirect effects arise due to the activation of structural elements along geological contacts, leading to the emergence of technogenic seismicity foci. The foci of induced seismicity are either confined to the blast points, or located along the tectonic structures crossing quarry fields. The technogenic impact on the geological environment transforms the independent local seismic process, since explosions trigger a chain of local seismic events. The near-surface layers of the Earth's crust become activated in the area of dynamic influence of active faults. Under the influence of explosions, both the number of seismic events and the average level of released energy alter. Impulse loads on the geological environment lead to a spatial redistribution of the foci of low-energy (K <7) earthquakes. The main form of the geodynamic development of seismogenic faults is the movement of their sides in the form of mutual “slippage”. Seismic events are manifested only when the aforementioned form of deformation is impossible or difficult to develop, in other words, when the stress-state areas of the Earth's crust develop. Therefore, the shaking impact of blasts can be considered as a factor contributing to the predominance of aseismic forms of fault motion in the form of smooth slippage of their sides. In conclusion, the impact of industrial blasts can not only activate faults around the mining area, but also have an unloading effect on the foci of seismic hazard forming in the interior, i.e. the redistribution of earthquake energy in terms of reducing earthquake energy class.


1992 ◽  
Vol 202 (2-4) ◽  
pp. 251-256 ◽  
Author(s):  
S.I. Kesselman ◽  
P.E. Kotliar ◽  
O.A. Kuchay ◽  
S.A. Tychkov ◽  
L.I. Serebriakova

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