Earthquake damage in underground roadways

Earthquake damage in underground roadways and mine workings is considered, with particular application to the mines operated by Solid Energy NZ Ltd., on the West Coast of New Zealand’s South Island. The scenario considered is the effect on the mine workings of an earthquake, of moment magnitude eight, being generated by a rupture of the Alpine fault. An empirical relation from the seismology literature is used to relate earthquake magnitude, distance from the epicentre and the peak ground acceleration resulting from the seismic waves. This relation is used to estimate the likely damage at the mine site. Also, the decay scale for Rayleigh (surface) waves is calculated and the implications for the mine workings considered. The two-dimensional scattering of shear (SH) seismic waves from the mine workings is considered. Analytical solutions relevant to various mine tunnel geometries are presented with the stress and displacement amplification, due to scattering from the mine workings, calculated and discussed

Deriving permeability distributions from fractal Gaussian tracer returns

Tracer returns in geothermal fields yield information about the connectivity between injection and production wells. We derive the equivalence between tracer returns described by a fractal Gaussian distribution, where diffusivity is scaled linearly with time, and tracer returns implied by one-sided Gaussian distributions of permeability. In this case, asymptotic tracer returns decay as the inverse square of time, and tracer returns are higher than predicted by methods assuming that asymptotic tracer returns decay exponentially with time. References J. Bear Dynamics of Fluids in Porous Media. American Elsevier, New York, 1972. M. W. Becker, A. M. Shapiro Tracer transport in fractured crystalline rock: Evidence of nondiffusive breakthrough tailing. Water Resour Res, 36(7), 1677-1686, 2000. doi:10.1029/2000WR900080. M. A. Grant, I. G. Donaldson, P. F Bixley Geothermal reservoir engineering. Academic Press, New York (1982) B. R. Kristjansson, G. Gudni Axelsson, G. Gunnarsson, I. Gunnarsson, F. Finnbogi Oskarsson, Comprehensive Tracer Testing in PROCEEDINGS, 41st Workshop on Geothermal Reservoir Engineering Stanford R. Haggerty, S. A. McKenna, L. C. Meigs, On the late-time behavior of tracer test breakthrough curves. Water Resour Res 36(12), 3467-3479, 2000. doi:10.1029/2000WR900214 A. Hunt, R. Ewing, B. Ghanbarian, Fractal Models of Porous Media. In: Percolation Theory for Flow in Porous Media. Lecture Notes in Physics, vol 880. Springer, 2014. I. Kocabas, R. N. Horne, Analysis of Injection-Backflow Tracer Tests in Fractured Geothermal Reservoirs. Proc. 12th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, SGP-Tr-109, Jan 20-22, 1987. P. Rose, K. Leecaster, S. Clausen, R. Sanjuan,M. Ames, P. Reimus, M. Williams, V. Vermeul, D. Benoit, A tracer test at Proc. 37th Workshop on Geothermal Reservoir Engineering, Stanford University, Jan. 30 - Feb. 1, 2012. D. A. Nield, A. Bejin, Convection in Porous Media. 2nd edn. Springer, New York (1999) A. E. Scheidegger, Horton's laws of stream lengths and drainage areas. Water Resources Res, 4(5), 1015-1021, 1968. doi:10.1029/WR004i005p01015. R. Schumer, D. A. Benson, M. M. Meerschaert, B. Baeumer Fractal mobile/immobile solute transport. Water Resources Res, 39(10), 1296, 2003. doi:10.1029/2003WR002141 G. Weir, J. Burnell, Analysing tracer returns from geothermal reservoirs. In: Proceedings of 30th NZ Geothermal Workshop, Auckland, New Zealand, pp. 24 - 26, 2014

Harbour porpoises (Phocoena phocoena) and minke whales (Balaenoptera acutorostrata) observed during land-based surveys in The Minch, north-west Scotland

Peer reviewedPublisher PD

Initial deformation about convex surfaces formed from identical, rough elastic–plastic bodies which approach along their normal at first contact

Abstract The low-velocity impact of two convex surfaces comprised of identical material, which approach each other along the direction of the normal at first contact, and obey a J 2 = k 2 plastic yield condition, is shown for very early times to satisfy the following conditions: the interior surface which separates the two bodies is equivalent to either the locus of points formed by the intersecting curves resulting from moving the two bodies towards each other along their normal; or to the locus of points formed from the level surfaces (suitably parametrized) drawn about each body at the time of first contact. This separating surface lies midway between the geometrical overlap of the two approaching surfaces for times sufficiently short for inertial effects not to significantly affect the approaching velocities. 2000 Mathematics subject classification: primary 74C99; secondary 52C35, 74A45

A response to “Likelihood ratio as weight of evidence: a closer look” by Lund and Iyer

Recently, Lund and Iyer (L&I) raised an argument regarding the use of likelihood ratios in court. In our view, their argument is based on a lack of understanding of the paradigm. L&I argue that the decision maker should not accept the expert’s likelihood ratio without further consideration. This is agreed by all parties. In normal practice, there is often considerable and proper exploration in court of the basis for any probabilistic statement. We conclude that L&I argue against a practice that does not exist and which no one advocates. Further we conclude that the most informative summary of evidential weight is the likelihood ratio. We state that this is the summary that should be presented to a court in every scientific assessment of evidential weight with supporting information about how it was constructed and on what it was based