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Publication Interpretive review of the acoustic borehole image logs acquired to date in the Wairakei-Tauhara Geothermal Field(Institute of Geological and Nuclear Sciences Limited, 2013) Massiot, Cécile; McNamara, David D.; Lewis, B.[No abstract available]Publication International ocean discovery program expedition 372 preliminary report: creeping gas hydrate slides and Hikurangi LWD, 26 November 2017 - 4 January 2018(Texan A&M University, 2018-03) McNamara, David D.International Ocean Discovery Program (IODP) Expedition 372 combined two research topics, slow slip events (SSEs) on subduction faults (IODP Proposal 781A-Full) and actively deforming gas hydrate bearing landslides (IODP Proposal 841-APL). Our study area on the Hikurangi margin, east of the coast of New Zealand, provided unique locations for addressing both research topics. SSEs at subduction zones are an enigmatic form of creeping fault behavior. They typically occur on subduction zones at depths beyond the capabilities of ocean floor drilling. However, at the northern Hikurangi subduction margin they are among the best-documented and shallowest on Earth. Here, SSEs may extend close to the trench, where clastic and pelagic sediments about 1.0 1.5 km thick overlie the subducting, seamount-studded Hikurangi Plateau. Geodetic data show that these SSEs recur about every 2 years and are associated with measurable seafloor displacement. The northern Hikurangi subduction margin thus provides an excellent setting to use IODP capabilities to discern the mechanisms behind slow slip fault behavior. Expedition 372 acquired logging-while-drilling (LWD) data at three subduction-focused sites to depths of 600, 650, and 750 meters below seafloor (mbsf), respectively. These include two sites (U1518 and U1519) above the plate interface fault that experiences SSEs and one site (U1520) in the subducting inputs sequence in the Hikurangi Trough, 15 km east of the plate boundary. Overall, we acquired excellent logging data and reached our target depths at two of these sites. Drilling and logging at Site U1520 did not reach the planned depth due to operational time constraints. These logging data will be augmented by coring and borehole observatories planned for IODP Expedition 375. Gas hydrates have long been suspected of being involved in seafloor failure; not much evidence, however, has been found to date for gas hydrate related submarine landslides. Solid, ice-like gas hydrate in sediment pores is generally thought to increase seafloor strength, as confirmed by a number of laboratory measurements. Dissociation of gas hydrate to water and overpressured gas, on the other hand, may weaken and destabilize sediments, potentially causing submarine landslides. The Tuaheni Landslide Complex (TLC) on the Hikurangi margin shows evidence for active, creeping deformation. Intriguingly, the landward edge of creeping coincides with the pinch-out of the base of gas hydrate stability on the seafloor. We therefore hypothesized that gas hydrate may be linked to creep-like deformation and presented several hypotheses that may link gas hydrates to slow deformation. Alternatively, creeping may not be related to gas hydrates but instead be caused by repeated pressure pulses or linked to earthquake-related liquefaction. Expedition 372 comprised a coring and LWD program to test our landslide hypotheses. Due to weather-related downtime, the gas hydrate-related program was reduced, and we focused on a set of experiments at Site U1517 in the creeping part of the TLC. We conducted a successful LWD and coring program to 205 mbsf, the latter with almost complete recovery, through the TLC and gas hydrate stability zone, followed by temperature and pressure tool deployments.Publication Methods and techniques employed to monitor and manage carbon capture and sequestration (CCS) induced seismicity(GNS Science, 2016) McNamara, David D.; |~|This report discusses the topic of induced seismicity resulting from the operations of subsurface CO2 injection at Carbon Capture and Storage (CCS) sites. The potential for induced seismicity to occur in CCS projects is an important factor when considering the capability of a project site s storage reservoir to retain injected CO2 for long periods of time. It is also important when assessing and addressing public concern over earthquake activity. This report discusses the measures carried out at global CCS sites to identify and monitor induced seismicity. This information is then distilled into a list of issues to be considered as part of the review process prior to establishing a CCS site in New Zealand.Publication A7 Makaroro River dam site Phase 1C: Field characterisation of possible secondary fault displacement(GNS Science, 2013) Langridge, R. M.; Villamor, P.; Litchfield, N. J.; Page, M.; Ries, W.; Ansell, I. A.; McNamara, David D.; Martin Gonzalez, F.; |~|GNS Science has undertaken a field study to investigate the possibility of active secondary faulting in the vicinity of the proposed A7 dam site on the Makaroro River, central Hawke’s Bay. The A7 site is located c. 750 m east of the primary active Mohaka Fault which has a short earthquake recurrence interval (average c. 1125 yr) and poses a credible shaking hazard to the dam site. Prior studies for the A7 dam site commissioned to GNS Science addressed the tectonic setting and characteristics of nearby active faults, as well as a literature review of the potential for secondary faulting at the dam site as a consequence of primary faulting along the Mohaka Fault. This current study focusses on site specific fieldwork undertaken to further evaluate the possibility of recent (late Quaternary) secondary faulting at, or near the proposed A7 dam site, and to define secondary faulting parameters such as possible displacement size, sense of movement, and recurrence. Based on our brief and previous investigations, we selected likely candidate sites for excavation to bedrock on the true left side of the valley on Smedley Station. The three trench sites were located to: 1) investigate the bedrock within the A7 dam footprint; 2) to intercept a NNE-striking mapped fault/shear zone; and 3) test whether evident linear hillslope geomorphology was related to recent faulting near the dam site. To assess recent displacement on bedrock exposed in the trenches we have: 1) mapped the bedrock structure (bedding and defects) in detail to identify faults/shear zones that could have potentially moved with fault displacements; 2) assessed whether bedrock faults had displaced the late Quaternary cover deposits or the strath surface (bedrock/cover contact); and, 3) assessed if fault rocks have characteristics of recent movement (i.e., non-cohesive materials such as fault breccias and gouge or clays. The surface fault rupture history of an active fault, the Gwavas Fault, located 5 km to the north of the A7 dam site and its relevance to the potential for faulting at the dam site have also been investigated through paleoseismic trenching.