The 1965–1967 Matsushiro earthquake swarm in central Japan exhibited two unique characteristics. The first was a hydro-mechanical crust rupture resulting from degassing, volume expansion of CO2/water, and a crack opening within the critically stressed crust under a strike-slip stress. The other was, despite the lower total seismic energy, the occurrence of complexed seismo-electromagnetic (seismo-EM) phenomena of the geomagnetic intensity increase, unusual earthquake lights (EQLs) and atmospheric electric field (AEF) variations. Although the basic rupture process of this swarm of earthquakes is reasonably understood in terms of hydro-mechanical crust rupture, the associated seismo-EM processes remain largely unexplained. Here, we describe a series of seismo-EM mechanisms involved in the hydro-mechanical rupture process, as observed by coupling the electric interaction of rock rupture with CO2 gas and the dielectric-barrier discharge of the modelled fields in laboratory experiments. We found that CO2 gases passing through the newly created fracture surface of the rock were electrified to generate pressure-impressed current/electric dipoles, which could induce a magnetic field following Biot-Savart’s law, decrease the atmospheric electric field and generate dielectric-barrier discharge lightning affected by the coupling effect between the seismic and meteorological activities.

Measurements of both thermal and lubrication properties of urea-based grease composites were conducted with and without additives of vapor grown carbon nanofiber (VGCNF) and solid lubricant molybdenum disulfide (MoS 2 ). As a result, a synergetic effect was found to greatly improve both the wear resistance and thermal properties of the urea grease composite with VGCNF and MoS 2 .

Using a versatile friction tester, a human forefinger was slid against six kinds of plain weave fabrics. The fabric materials were cotton, cupra, nylon, silk, polyester and wool. Fifteen student men cooperated as an examinee in this test. Main aim of the test is to study the relationship between the characteristics feature of tactile sensing based on semantic differential method and the frictional characteristics. To this end, multivariate analysis method was employed. The results are summarized as follows : 1) In the range of the finger press force of 0.5 -2N, the mean frictional coefficient was independent of the finger press force, of which Amonton-Coulomb's law of friction held.2) The mean friction coefficient of silk averaged over 15 examinees was as high as 1.05, while that of nylon was as low as 0.70. 3) The human factor was appreciable for the frictional behavior ; i.e., for almost half of the examinees, the frictional signals of both cotton and cupra showed the stick-slip phenomena, but the rests were not. The mean friction coefficient of the finger/fabrics depended on the difference of finger characteristics of individuals. For some of the examinees, the friction coefficient was independent of the kind of fabrics. 4) The lower friction coefficient of the fabrics was recoded in the lower room temperature. 5) Based on the multivariate analysis of the touch sensory test results, the stick-slip type frictional characteristics of cotton and cupra is discussed in relation to the human factor.

In this paper, we investigate the mysterious tsunami fires that occurred at Aonae Harbor on Okushiri Island during the 1993 Hokkaido Nansei-Oki earthquake. Specifically, five fishing boats moored separately from each other in the harbor suddenly caught fire and burned nearly simultaneously with the arrival of the first tsunami wave. However, the ignition mechanism of those fires has, until now, remained largely unknown. At the time the earthquake occurred, an NHK (Japan Broadcasting Corporation, Tokyo, Japan) crew that was on the island to report on its scenic natural attractions just happened to capture video footage of those tsunami-related fires. Using that NHK video footage in combination with eyewitness accounts, this study investigates the spatio-temporal process leading to those tsunami-related fires. For example, one witness said, "There was whitish bubbling in the offshore area and I saw five burning fishing boats moored on the seawall being blown about by the strong winds. The burning boats were swept ashore with the tsunami and ignited the gasoline of a car that was rolling in the waves. The fire eventually spread to the center of the Aonae District." The NHK video footage confirmed flames arising from the five fishing boats almost simultaneously and the shimmering white color of the tsunami waters striking the seawall, which were consistent with the eyewitness testimony. Based on these spatio-temporal data, we propose the following hypothetical model for the origin of tsunami fires. Combustible methane gas released from the seabed by the earthquake rose toward the surface, where it became diffused into the seawater and took the form of whitish bubbles. The tsunami strike on the Aonae Harbor seawall resulted in the generation of large electrical potential differences within the seawater mist, which quickly developed sufficient electrical energy to ignite the methane electrostatically. The burning methane bubbles accumulated on the boat decks, which then burned violently.