A new apparatus for measuring elastic wave velocity and electrical conductivity of fluid‐saturated rocks at various confining and pore‐fluid pressures

Pore‐fluid pressure is a critical parameter that governs geodynamic processes including seismic activities. Its evaluation through geophysical observations provides us insights into these processes. The quantitative evaluation requires a thorough understanding of the influence of pore‐fluid pressure on geophysical parameters, such as seismic velocity and electrical conductivity. To study the influence of pore‐fluid pressure on these parameters, we have built a new apparatus with a pore‐fluid pressure control system, which is capable of simultaneously measuring elastic wave velocity and electrical conductivity. Our new apparatus employs two sets of plastic piston–cylinders for the electrical insulation and pore‐fluid pressure transmission. The pore fluid is electrically isolated from the metal work, and its pressure can be precisely controlled without significant contribution of the friction between the piston and cylinder. Our new apparatus was used for a simultaneous measurement of velocity and conductivity in a brine‐saturated Berea sandstone. Elastic wave velocity and electrical conductivity changed in response to the change in confining and pore‐fluid pressures, showing the usefulness of the new apparatus.     

Do temporal size differences influence species identification of archaeological albatross remains when using modern reference samples?

Zooarchaeological remains have been identified to species, using identification criteria based on specific morphological variations among modern specimens. However, temporal size changes in bones, due to micro-evolution and/or phenotypic plasticity, could distort identification of archaeological remains according to these criteria. We developed species identification criteria for North Pacific albatrosses (Short-tailed, Laysan and Black-footed Albatrosses) using both mensural- and DNA-based analysis and actually identified many archaeological remains from a site using these criteria. Our mensural-based criteria could accurately discriminate the modern Short-tailed Albatross from modern Laysan and Black-footed Albatrosses and indicated that the archaeological remains included both Short-tailed and Laysan or Black-footed Albatrosses. DNA-based criteria, however, suggested that all remains were Short-tailed Albatross. The most plausible explanation for this inconsistency would be misidentification using mensural-based analysis, due to temporal size changes in bones or existence of birds from extinct population(s) or breeding region(s) with mensurally different bones from recent birds. This is the first study that suggests temporal size changes in bones may distort the species identification of archaeological remains according to modern size variations. Further studies are required to judge if this pattern is unusual or not.