[1] Sediment dominated convergent margins typically record substantial horizontal shortening often associated with great earthquakes. The convergent margin south of Japan is arguably one of the most extensively investigated margins and previous studies have documented extensive evidence for accretion and horizontal shortening. Here, we show results from anelastic strains recovered from three partially lithified sediment samples ($40% porosities) across the southwest Japan accretionary prism and propose that the margin is dominated by horizontal extension rather than compression. The anelastic strain results are also consistent with stress directions interpreted from two independent techniques -bore hole breakout orientations and core-scale fault data. We interpret this unexpected result to reflect geologically recent underthrusting of a thick sediment package and concomitant weakening of the decollément. Citation: Byrne, T. B.,

Abstract:To better understand the distribution of three dimensional stress states in the Nankai subduction zone, southwest Japan, we review various stress-related investigations carried out in the first and second stage expeditions of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) by the Integrated Ocean Drilling Program (IODP) and compile the stress data. Overall, the maximum principal stress 1 in the shallower levels (<~1km) is vertical from near the center of forearc basin to near the trench and; the maximum horizontal stress SHmax (interpreted to be the intermediate principal stress 2) is generally parallel to the plate convergence vector. The exception to this generalization occurs along the shelf edge of the Nankai margin where SHmax is along strike rather than parallel to the plate convergence vector. Reorientation of the principal stresses at deeper levels (e.g., >~1km below seafloor or in underlying accretionary prism) with 1 becoming horizontal is also suggested at all deeper drilling sites. We also make a comparison of the stress state in the hanging wall of the frontal plate-interface between Site C0006 in the Nankai and Site C0019 in the Japan Trench subduction zone drilled after the 2011 Mw9.0 Tohoku-Oki earthquake. In the Japan Trench, the A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT3 comparison between stress state before and after the 2011 mega-earthquake shows that the stress changed from compression before the earthquake to extension after the earthquake. As a result of the comparison between the Nankai Trough and Japan Trench, a similar current stress state with trench parallel extension was recognized at both C0006 and C0019 sites. Hypothetically, this may indicate that in Nankai Trough it is still in an early stage of the interseismic cycle of a great earthquake which occurs on the décollement and propagates to the toe (around site C0006).

Few data on stress symptoms related to the World Trade Center disaster in law enforcement personnel have been reported. Most New York City Police Department (NYPD) officers had significant exposure to the events of Sept. 11, 2001. Approximately 5,000 officers responded within the first 2 days, and more than 25,000 officers worked at ground zero, the morgues, or the Staten Island landfill. Because the police are the first line of defense against terrorist attacks, it is imperative that they maintain optimal health and functioning. Concern for the long-term effects from traumatic exposure is warranted. In partnership with Project Liberty, peer officers and clinicians from the Police Organization Providing Peer Assistance performed outreach, support work, and screening for stress symptoms related to the disaster in the NYPD from December 2002 until December 2003. Psychological issues in law enforcement personnel, a description of the outreach program, and data from these screenings are presented.

Space-based geodetic observations show that the Coso Range and Indian WellsValley lie along the southeastern margin of the Sierra Nevada-Central Valley (i.e., "Sierran") microplate, which moves ϳ13-14 mm/yr northwest with respect to stable North America. Detailed kinematic analysis of seismicity indicates that active crustal extension in the Coso Range occurs in a right-lateral transtensional regime along the eastern border of the Sierran microplate. The Airport Lake fault in the northern Indian Wells Valley and the Owens Valley fault are the major strike-slip faults along the eastern margin of the Sierran microplate south and north, respectively, of the Coso Range. Patterns of seismogenic deformation and Quaternary faulting indicate that dextral shear passes through the Coso Range in a right-releasing stepover between the Airport Lake and Owens Valley faults. Extension within the stepover region is accommodated in part by opening of Coso Wash as a pull-apart basin. The stepover is bounded on the east by a blind, northwest-striking dextral fault that is well expressed by patterns of microseismicity. Comparison with analogue sandbox models of pull-apart basins suggests that the Coso stepover is a relatively immature structure, consistent with models for a westward step in the locus of dextral shear along the eastern margin of the Sierran microplate to the Indian Wells Valley and Owens Valley in the past 2-3 m.y.

The pressure and temperature history of the Tertiary Shimanto belt of south‐west Japan has been elucidated by analysing fluids trapped in quartz crystals which grew syn‐kinematically along late‐stage brittle faults. The samples come from three areas that span the Paleogene exposures on the Muroto Peninsula of Shikoku Island. Applying microthermometric and laser Raman microsampling techniques to coeval water‐rich and carbonic fluid inclusions, we have constrained the pressure and temperature conditions that accompanied a widespread and kinematically distinct phase of deformation. The results suggest elevated geothermal gradients during late‐stage deformation, conditions that are in disaccord with previous plate reconstructions that have depicted old, thermally mature Pacific crust subducting beneath Eurasia during the early to middle Tertiary. These conditions can most easily be accounted for by including an additional plate boundary in the western Pacific during Paleogene time. Plate reconstructions that include the Kula plate in this region are therefore consistent with our findings. In addition, our results provide clues to the conditions that likely accompany seismogenic deformation at active convergent plate boundaries.