Mechanical properties of the cored sediments are discussed in several papers. Riedel et al. (this volume) present data on a broad suite of physical properties measurements from the upper 10–20 mbsf. These results are important because of the poor quality of logs from these depths. Apparent overconsolidation of shallow sediments from the ridge (Sites 1244, 1245, and 1246) and normal consolidation in the slope basin (Sites 1251 and 1252) supports the inference from seismic stratigraphic analysis that the ridge is presently an erosional environment.
Tan et al. (this volume) present results of consolidation tests on whole-round samples from Site 1244, which provide important background information for future hydrological analyses. Winters et al. (this volume) present results of consolidation tests on a sample from the summit region that was thought to have contained gas hydrate, based on an IR anomaly recorded on board. This sample was repressurized to in situ pressure immediately after recovery; however, no gas hydrate was observed when the sample was removed from the pressure vessel for mechanical tests.
Borehole breakouts observed in the electrical resistivity logs provide unique information on the orientation of the present stress field at SHR and on the in situ mechanical properties of gas hydrate–bearing sediments (Goldberg and Janik, this volume). At Sites 1244 and 1245, the stress direction is dominated by the topographic effect of SHR, whereas at Site 1251, in the slope basin, the stress direction is approximately perpendicular to the plate convergence direction. Except at the summit, which is characterized by chaotic fracturing indicative of free gas migration, the orientations of resistive fractures, also imaged by the resistivity logs, are consistent with these stress directions (Weinberger and Brown, 2006).