Present-day stress orientation in Thailand's basins

Abstract

10The Cenozoic tectonic evolution of Thailand is widely considered to have been primarily 11 controlled by forces generated at the eastern Himalayan syntaxis. This hypothesis is supported by 12 earthquakes in northern Indochina and southern China, which reveal a fan shaped present-day 13 maximum horizontal stress (S Hmax ) pattern centered on the eastern Himalayan syntaxis. However, 14 the distance to which forces generated by the Himalayan syntaxis influence the stress pattern in 15 Indochina is not known. We analyzed caliper and image logs from 106 petroleum wells for 16 borehole breakouts and drilling-induced fractures. A total of 558 breakouts and 45 drilling-17 induced fractures were interpreted in six basins, indicating that a north-south regional present- processes also influence the stress field in Thailand. We suggest that stresses generated by the 27 Sumatran-Andaman subduction zone may also have resulted in significant deformation in 28 offshore Thailand and that the stress pattern may also be perturbed at very local (several km) 29 scales by mechanically weak faults. 30 31

Influence of fault reactivation during multiphase rifting: the Oseberg area, Northern North Sea rift

“…Specifically, basement structures and pre-existing faults lead to variation in the strike of new faults from orthogonal to oblique to the regional far-field stress of rifting (Morley, 2010;Tingay et al, 2010). This is consistent with that made from physical modeling of two phases of non-coaxial extension (Henza et al, 2010;, where reactivation of first-phase faults (N-S-striking faults 35 in Fig.…”

The Italian present-day stress map

“…In fact, as several authors have argued (e.g. Tingay et al 2010a,b) D‐quality data may best reflect local stress variations and sometimes may provide insight to larger scale stress fields. In particular along the northern offshore of Sicily (Kabylian–Calabrian thrust front), several earthquakes, with prevalent reverse focal mechanisms, describe a clear ∼NNW–SSE current compression (Fig.…”

Regional and local stress field orientation inferred from quantitative analyses of extension joints: Case study from southern Italy

“…[39] The occurrence of major tectonic structures can perturb the first-order stress field, causing second-order reorientations of the principal stress axes which depend on the spatial arrangement of the fault segments, their kinematics, and stress magnitude [Bell, 1996;Yale, 2003]. Rotations of the horizontal stress components have been observed at all scales [Rawnsley et al, 1992;Acocella et al, 2002;Caputo, 2005;Tingay et al, 2005Tingay et al, , 2010Tingay et al, , 2012] and computed simulating different kinematics and geometrical settings [Homberg et al, 1997;Huggins et al, 1995;Maerten et al, 2002;Soliva et al, 2008]. [40] In the investigated sites, where the regional WNW-ESE tension is not locally recorded, we considered the possibility of fault-induced perturbations.…”