CREWES participated in two collaborative seismic surveys that were conducted in New Zealand in early 2016. The target of interest in the Whataroa valley (South Island) is the Alpine Fault, which forms part of the boundary between the Australian and Pacific Plates in southern New Zealand, and has the potential to produce M8+ earthquakes. The Deep Fault Drilling Project (DFDP) drilled and instrumented borehole DFDP-2b prior to the seismic program. The Hauraki Rift survey (North Island) crossed the northern Kerepehi fault, which has previously been inferred from gravity data. The Kerepehi fault is considered to be active, and is thought to have produced M6+ earthquakes in the past. The primary objective of both programs was to better define seismic velocities and geometries of faults that are known to be earthquake risks. Initial processing of surface seismic data has provided relatively good images of sediments, the base of sediments and, we believe, the Alpine and Kerepehi faults.

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We describe a seismic field experiment and subsequent data analysis designed to test the performance of common sources and receivers at low frequencies. Both dynamite and vibroseis sources were tested. Receivers tested included Vectorseis (MEMs) and both 4.5 Hz and 10 Hz geophones.Dynamite produced the strongest lowfrequency signal but vibroseis was able to operate effectively down to around 2 Hz using low-dwell sweeps. Both geophones recovered low frequency signal down to 1-2 Hz after correction for their intrinsic response. Vectorseis produced a strong response to very low frequencies but increasing noise becomes a progressive problem.

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In 2016-2017 a range of analyses and applications of a geometrical model of fibre-optic (DAS) data for arbitrary fibre shapes was described. Amongst those applications was a multicomponent estimation scheme based on a careful accounting, and combined useage, of the varying fibre directions associated with a shaped cable layout. In 2018 a prototype shaped DAS fibre array was buried at the Containment and Monitoring Institute Field Research Station in Newell County AB to put some of these ideas and their feasibility to the test. The loop was illuminated from several directions, and shot records were analyzed to assess if directional sensitivity is sufficient to permit multiple components of strain to be estimated simultaneously. By picking a P-wave arrival and comparing it to an analytic model, we conclude with a cautious "yes". The size of the loop (roughly 10m on a side) was chosen to accommodate standard DAS gauge lengths; at this size, horizontal but not vertical strain rate components were sensed. Future versions designed for gauge lengths on the order of 2m will permit 6-component estimation.