Focal mechanisms and moment magnitudes of micro-earthquakes in central Brazil by waveform inversion with quality assessment and inference of the local stress field

2016 ◽  
Vol 71 ◽  
pp. 333-343 ◽  
Author(s):  
Juraci Carvalho ◽  
Lucas Vieira Barros ◽  
Jiří Zahradník
Keyword(s):  
Stress Field ◽  
Quality Assessment ◽  
Waveform Inversion ◽  
Local Stress ◽  
Focal Mechanisms ◽  
Central Brazil ◽  
Local Stress Field

scholarly journals Local stress field inverted for a shale gas play based on focal mechanisms determined from the joint source scanning algorithm

2021 ◽  
Vol 34 (0) ◽  
pp. 1-12
Author(s):  
Chuntao Liang ◽  
◽  
Yangyang Yu ◽  
Furong Wu ◽  
Liang Kang ◽  
...  
Keyword(s):  
Stress Field ◽  
Shale Gas ◽  
Local Stress ◽  
Focal Mechanisms ◽  
Scanning Algorithm ◽  
Local Stress Field

scholarly journals Activation of optimally and unfavourably oriented faults in a uniform local stress field during the 2011 Prague, Oklahoma, sequence

2020 ◽  
Vol 222 (1) ◽  
pp. 153-168 ◽  
Author(s):  
Elizabeth S Cochran ◽  
Robert J Skoumal ◽  
Devin McPhillips ◽  
Zachary E Ross ◽  
Katie M Keranen
Keyword(s):  
Stress Field ◽  
Compressive Stress ◽  
Local Stress ◽  
Wastewater Disposal ◽  
Principal Compressive Stress ◽  
Vertical Fault ◽  
Major Fault ◽  
Pressure Changes ◽  
Earthquake Sequences ◽  
Local Stress Field

SUMMARY The orientations of faults activated relative to the local principal stress directions can provide insights into the role of pore pressure changes in induced earthquake sequences. Here, we examine the 2011 M 5.7 Prague earthquake sequence that was induced by nearby wastewater disposal. We estimate the local principal compressive stress direction near the rupture as inferred from shear wave splitting measurements at spatial resolutions as small as 750 m. We find that the dominant azimuth observed is parallel to previous estimates of the regional compressive stress with some secondary azimuths oriented subparallel to the strike of the major fault structures. From an extended catalogue, we map ten distinct fault segments activated during the sequence that exhibit a wide array of orientations. We assess whether the five near-vertical fault planes are optimally oriented to fail in the determined stress field. We find that only two of the fault planes, including the M   5.7 main shock fault, are optimally oriented. Both the M 4.8 foreshock and M   4.8 aftershock occur on fault planes that deviate 20–29° from the optimal orientation for slip. Our results confirm that induced event sequences can occur on faults not optimally oriented for failure in the local stress field. The results suggest elevated pore fluid pressures likely induced failure along several of the faults activated in the 2011 Prague sequence.

A simplified method to predict the local stress field and N-SIF of V-shaped notch

2020 ◽  
Vol 234 ◽  
pp. 107096 ◽  
Author(s):  
Wei Shen ◽  
Guiming Liang ◽  
Chunmei Li ◽  
Enqian Liu
Keyword(s):  
Stress Field ◽  
Local Stress ◽  
Simplified Method ◽  
Local Stress Field

Seismic anisotropy time variations at Mt Etna

2019 ◽  
Vol 220 (1) ◽  
pp. 450-460
Author(s):  
Lucia Nardone ◽  
Francesca Bianco ◽  
Lucia Zaccarelli ◽  
Domenico Patanè
Keyword(s):  
Time Delay ◽  
Stress Field ◽  
Shear Wave ◽  
Local Stress ◽  
Temporal Variations ◽  
Fast Wave ◽  
Polarization Direction ◽  
Stress Changes ◽  
Mt Etna ◽  
Local Stress Field

SUMMARY The aim of this paper is to study the temporal variations in the seismic wavefield associated with the stress changes in the dynamic features of the Mt Etna volcanic activity. We used shear wave splitting analysis on a huge data set of local earthquakes, in order to identify changes of the local stress field at Mt Etna during the time interval from 2006 to 2011. This analysis allows us to obtain two parameters: the polarization direction of the fast shear wave (φ) and the time delay of the slow shear wave (Td,time delay between the split shear waves). Orientation of φ generally provides information about the anisotropic symmetry and stress direction whereas Td provide information about the average crack density along the ray path. Based on our findings it is possible to divide Etna Volcano in three different sectors, each one distinguished by typical fast wave polarization direction. We find that the western part of the volcano is controlled by the regional tectonic stress field having a NS and EW directions. Instead, the eastern part of the volcano is mainly controlled by the local volcanic stress, particularly an EW local stress field in the NE sector (Pernicana), and a quasi NS local stress field in the SE sector (Mascalucia, Timpe), where previous studies evidenced: (i) some low-Qp anomaly regions between 0 and about 6 km depth, probably associated with high pore pressure and the intense faulting and (ii) by magnetotelluric surveys, several high conductivity zones, up to 8 km depth, related to a diffuse presence of hydrothermal activity and fluid circulation. Temporal variations in time delay, mostly before the 2008–2009 lateral eruption, can be interpreted as stress accumulation increase with a consequent release of stress due to coalescing of microcracks in the conduit for the eruption of magma.

Modeling the local stress field and kinematics of the San Andreas fault system

1979 ◽  
Vol 52 (1-4) ◽  
pp. 647-663 ◽  
Author(s):  
D.N. Osokina ◽  
A.A. Nikonov ◽  
N.Yu. Tsvetkova
Keyword(s):  
Stress Field ◽  
San Andreas Fault ◽  
Local Stress ◽  
Fault System ◽  
San Andreas ◽  
San Andreas Fault System ◽  
Local Stress Field

Size Dependent Micro-Stress-Field of Fibers in Eutectic Ceramic Rod

2010 ◽  
Vol 168-170 ◽  
pp. 226-229
Author(s):  
Hai Xing Lu ◽  
Xie Quan Liu ◽  
Xin Hua Ni ◽  
Tao Sun ◽  
Bao Feng Li
Keyword(s):  
Stress Field ◽  
Local Stress ◽  
Apparent Size ◽  
Average Strain ◽  
Size Dependent ◽  
Three Phase ◽  
Stress Boundary Condition ◽  
Stress Boundary ◽  
Remote Stress ◽  
Local Stress Field

Considering the interaction between fiber-inclusion and strong constraining interphase, forth-phase model is suggested to determine the local stress field distribution of three-phase element in eutectic ceramic rod. On the basis of the volumetric average strain, the effective compliance tensor increment of eutectic ceramic rod is obtained. The remote stress boundary condition of the eutectic ceramic rod is accounted for getting the micro stress field of fibers in eutectic ceramic rod. The results show the micro stress field of the fiber-inclusion in eutectic ceramic rod is associated with the stiffness and the volume fractions of each component in eutectic ceramic rod, the shape of interphase and fiber. The micro stress field has apparent size effect: three direction stresses increase with the diameter of fiber- inclusion.

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