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The final version of the above article was posted prematurely on 16 July 2021, owing to a technical error. The final, corrected version of record will be made fully available at a later date.

The Longmaxi shale is an extensive, prolific unconventional play in southwestern China. Its development in the Changning area is affected by ineffective hydraulic fracturing (HF) stimulation, fault reactivation and casing damage. It is suspected that the stress contrast within and between the shale reservoirs and the formations above and below matters to hydraulic fracture propagation and reservoir stimulation. To this end, the Longmaxi shale in the Changning area deserves a dedicated quantification of the in situ stress state and its variations. In this study, we re-visit the available data from one of the play's first appraisal wellbores (X01) for an integrated geomechanics study, focusing on profiling the stress across the Longmaxi and its adjacent formations. Combining geophysical logs and other stress indicators, we re-interpret its stress profile in the context of lithological variations. The resulting stress variations are modeled primarily through a viscoplastic stress relaxation framework, compared with the results via the frictional equilibrium and an elastic theory (the Extended Eaton model). We offer some discussions on the differences and similarities of these stress profiling methods, and examine their applicability to Longmaxi shale in the Changning area. Our objective is to connect the lithology-controlled stress variations to the first-order complexities (HF ineffectiveness and fault reactivation) that have been observed in the area to date. [ABSTRACT FROM AUTHOR]

We present shear velocity anisotropy data from crustal earthquakes in California and demonstrate that it is often possible to discriminate structural anisotropy (polarization of the shear waves along the fabric of major active faults) from stress-induced anisotropy (polarization parallel to the maximum horizontal compressive stress). Stress directions from seismic stations located near (but not on) the San Andreas fault indicate that the maximum horizontal compressive stress is at a high angle to the strike of the fault. In contrast, seismic stations located directly on one of the major faults indicate that shear deformation has significantly altered the elastic properties of the crust, inducing shearwave polarizations parallel to the fault plane. Keywords: crustal stress, seismic anisotropy, San Andreas fault.

We have integrated in situ stress, neotectonic, and Global Positioning System data to investigate the complex interactions among the South American, Caribbean, and Nazca plates and the Costa Rica--Panama microplate and to examine different seismotectonic models that have been proposed for the region. The resulting data set was used to generate an integrated stress map of the region that shows that the stress field in northern South America varies systematically in both orientation and relative magnitude. In the southwestern part of the study area, the Ecuadorian Andes stress province exhibits strong EW compression resulting from the subduction of the Nazca plate beneath the South American plate. In the North Andes stress province, the observed NW-SE compression may result from the convergence between the Caribbean and the South American plates and/or the negative buoyancy of the already subducted Caribbean plate beneath northwestern South America. Possible convergence between the Costa Rica--Panama microplate with respect to northwestern South America may also be a source of compression in this region. In north and northeastern Venezuela, normal and strike-slip faulting with a NE-SW direction of extension characterizes the San Sebastian--El Pilar stress province. Keywords: Caribbean, South America, stress, seismotectonics, Global Positioning System, Northern Andes.