Evidence for late Quaternary surface rupture along the Leech River fault near Victoria, British Columbia

New surficial and bedrock mapping and paleoseismic trenching of the Leech River fault provide the first evidence for Quaternary surface-rupturing earthquakes in southwestern British Columbia, Canada. The Leech River fault extends ~60 km across southern Vancouver Island, from Victoria, British Columbia to the Pacific shoreline and is a terrane-bounding structure separating the Pacific Rim Terrane from basalts of the Eocene Crescent Terrane. The fault is not currently listed in the active fault catalogue for Canada, and post-Eocene-Oligocene slip had not been documented prior to this study. However, based on new field mapping aided by lidar topography, we identify >60 individual, sub-parallel, linear scarps, sags and swales occurring in semi-continuous, en echelon arrays that offset bedrock and late Pleistocene-Holocene deposits. Field observations of these scarps confirm that they are not the result of anthropogenic, glacial or landslide processes, and in several places the scarps are located above exposures of faulted bedrock with brittle fracture networks and gouge. At a site ~5 km west of Leechtown, British Columbia, we estimate ~6 m of dip-slip reverse displacement of a post-Last Glacial Maximum (<~15 ka) colluvial surface and ~4 m of displacement of intervening channels. Two paleoseismic trenches at this site reveal (1) Jurassic Leech River Schist in fault contact with latest Pleistocene loess and colluvium, and (2) latest Pleistocene till thrust over post-glacial colluvium. These trenches preserve a record of at least three, and possibly four, earthquakes since the Last Glacial Maximum, each with ~1 m vertical displacement. We interpret the active Leech River fault as a 500–1000 m-wide, steeply dipping fault zone that accommodates transpression across the northern Cascadia forearc. The onshore trace of the Leech River fault may continue offshore to the east, south of Victoria, and may be kinematically linked to active faults in western Washington (e.g., Devils Mountain and Southern Whidbey Island faults). The Leech River fault is likely one of several active crustal faults that should be considered in seismic hazard assessments for southern British Columbia and northwestern Washington

Double Dilation ≠\neq Double Mixing (extended abstract)

Density operators are one of the key ingredients of quantum theory. They can be constructed in two ways: via a convex sum of 'doubled kets' (i.e. mixing), and by tracing out part of a 'doubled' two-system ket (i.e. dilation). Both constructions can be iterated, yielding new mathematical species that have already found applications outside physics. However, as we show in this paper, the iterated constructions no longer yield the same mathematical species. Hence, the constructions 'mixing' and 'dilation' themselves are by no means equivalent. Concretely, when applying the Choi-Jamiolkowski isomorphism to the second iteration, dilation produces arbitrary symmetric bipartite states, while mixing only yields the disentangled ones. All results are proven using diagrams, and hence they hold not only for quantum theory, but also for a much more general class of process theories.Comment: In Proceedings QPL 2017, arXiv:1802.09737. This paper is the shorter version of arXiv:1704.02309; all missing proofs can be found in the full versio

Feature-based characterisation of evolving surface topographies in finishing operations for additive manufacturing

Finishing operations play a fundamental role in the additive manufacture of components. Conventional surface metrology solutions allow for the characterisation of surface roughness through texture parameters, but are not fully suitable to capture the evolution of individual surface topographic formations as they undergo changes as a result of finishing operations. Feature-based characterisation of topography offers a new perspective in the investigation of surfaces. The approach consists of the identification, isolation, and dimensional characterisation of surface topography formations (surface features). In this work an original feature- based solution is proposed for the quantitative comparison of topographies before and after a finishing operation: the approach is based on the registration of areal topography datasets and quantitative analysis of shape and size differences pertaining to the relevant topographic features. A variety of finishing operations are investigated on metallic samples manufactured via powder bed fusion

Multirole Logic (Extended Abstract)

We identify multirole logic as a new form of logic in which conjunction/disjunction is interpreted as an ultrafilter on the power set of some underlying set (of roles) and the notion of negation is generalized to endomorphisms on this underlying set. We formalize both multirole logic (MRL) and linear multirole logic (LMRL) as natural generalizations of classical logic (CL) and classical linear logic (CLL), respectively, and also present a filter-based interpretation for intuitionism in multirole logic. Among various meta-properties established for MRL and LMRL, we obtain one named multiparty cut-elimination stating that every cut involving one or more sequents (as a generalization of a (binary) cut involving exactly two sequents) can be eliminated, thus extending the celebrated result of cut-elimination by Gentzen