The Philippine Sea coast of central-southwest Japan tilts oceanward during interseismic periods and peninsulas uplift suddenly at the time of great earthquakes. Tide gauge data indicate that precursory uplifts of the peninsulas occurred during about the decade prior to the occurrence of recent earthquakes. I construct a model to interpret the precursory uplifts on the basis of the model which assumes a fractal distribution of asperities. I calculate uplifts due to slow failures of smaller asperities contained in the rupture zone, assuming that the probability of breakage of the smallest unit asperity increases linearly over time. The time of breakage of one of the largest asperities is the time of the occurrence of a great earthquake, t_f. I conduct a least squares fitting to the residual uplift data prior to great earthquakes to constrain t_f. Applications to tide gauge data before the 1923 and 1946 earthquakes give t_f= 1923.2 (±1.6), and 1943.7 (±2.7), respectively. For the expected Tokai earthquake, I obtain t_f= 2007.6 (-5.4, +2.8) using precise leveling data. The intermediate-term precursors of a decade may be useful to limit the expected time of occurrence of coming great earthquakes, filling the gap between long-term and short-term earthquake predictions.

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A case study is presented for applications of paleomagnetism in the volcanic field. First, the importance of magnetic cleaning was demonstrated for the present-day pyroclastic flow. Some blocks contained a very large secondary component which was removed only after heating to temperatures over 400°C. Second, progressive thermal demagnetization was used to determine the cooling history of volcanic products. In the case of a block-and-ash flow found at a depth of 450 m in a drill core, the emplacement temperature varied from block to block, giving inconsistent results. Some blocks, however, might have undergone rotations during cooling because one or two sharp kinks were often recognized in the orthogonal plots of thermal demagnetization. In another case of a Holocene block-and-ash flow, the remanence directions for block samples were completely scattered. This contradictory observation is interpreted by an eruptive sequence that the blocks had already cooled down below the blocking temperature at the summit when the lava dome was at the stage of endogenous formation. Finally, case studies of lava identification by remanence directions are given. For some lava flows which are coeval in terms of volcano-stratigraphy, remanence directions are different beyond the error, suggesting a short time gap between their extrusion.

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We consider the interaction of Alfven waves with the auroral acceleration region (AAR). The AAR is characterized by an electric potential drop that supports a field-aligned upward current and the acceleration of precipitating electrons. An Alfven wave incident on the AAR from the magnetosphere partially reflects back and partially penetrates into the AAR. The rate of wave reflection/transmission is estimated to be critically dependent on the wave transverse scale. Magnetospheric Alfven waves penetrating into the AAR can produce oscillatory variations of the field-aligned potential drop, thus constituting a new mechanism of ULF modulation of electron acceleration. Estimates of the potential drop modulation by Alfven waves are provided within the “thin” AAR approximation, which is valid for a wide range of wave and plasma parameters. The proposed mechanism will produce nearly simultaneous ULF magnetic and riometric variations at auroral latitudes. Occurrence of the AAR-associated resonator in the auroral topside ionosphere between the bottom boundary of the AAR and the E-layer may cause oscillatory frequency dependence of electron acceleration modulations in the range around fractions of a Hz. Another feature of the mechanism considered is the critical dependence of the ratio between the magnetic and riometric signals on the transverse scale of the disturbance. The predicted effects are to be searched for in the simultaneous data of IRIS multi-beam riometers and magnetometers.

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We examined the magnetic fields and energetic particle data from geosynchronous satellites GOES 6 and S/C1984-129 during the multiple onset of Pi2. We found that the energetic particle injection in the midnight sector was associated with the consecutive Pi2 onset. The magnetometer on board GOES 6 at the midnight sector detected the increase of the field inclination as well as a decrease of the field magnitudes during the Pi2 events. We suggest that such a field reconfiguration could be provoked by the formation of the dusk-to-dawn currents in the vicinity of the geosynchronous altitudes. The present study supports the Pi2 model that the impulsive dusk-to-dawn current and field-aligned current diverted from it are a source of Pi2 pulsation in the midnight magnetosphere.

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The photo-stability of simulated free and bound amino acids exposed to photon sources of 1.2-1.3 MeV γ-rays from a ⁶⁰°C source and ultra-violet (UV) irradiation from a 10 eV deuterium lamp was examined. The free amino acids in aqueous solution were drastically decreased while the bound amino acids in aqueous solution were slightly decreased with the duration of γ-rays and UV irradiation. The apparent half-lives (t_1/2) of bound serine and threonine under γ-rays irradiation were more than 10.6 and 27.9 times as stable as the free amino acids, respectively. The photo-stability of bound amino acids was greater than that of free amino acids under irradiation by high-energy photons. These results strongly suggest that bound, but not free, amino acids could be found in extraterrestrial environments. Radio- or photo-alteration processes are mainly decomposition pathways, with the production of secondary amino acids via decomposition of the α-carboxylic group; β-alanine and γ-aminobutyric acids, α-decarboxylation products of aspartic acid and glutamic acid, respectively, were detected.

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The permanent Global Positioning System (GPS) array in Japan detected coseismic and postseimic deformation of the 2003 Tokachi-oki earthquake (M_ω 8). We estimate the time evolution of its postseismic slip, together with its coseismic slip distribution. The result shows that the postseismic slip has been occurring mainly in an area adjacent to the coseismic slips, propagating to the northeast and southwest. This suggests that, as of March 6, 2004, the postseismic slip of the strongly coupled area neighboring the coseismic rupture partly released seismic moment, equivalent to an earthquake of M_ω 7.8.

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Two-dimensional magnetopause structure with a series of pearl-like magnetic islands at the dawn side of the equatorial plane was reported earlier by Hau and Sonnerup (1999) from the AMPTE/IRM data by solving the Grad-Shafranov equation as a spatial initial value problem. This paper presents another rare event that appears like the image of the dawn event at the dusk side magnetopause based on the analysis of two years satellite data and similar reconstruction method. The two crossings occur at (x, y, z) = (7.13, -6.64, 0.4) and (7.93, 9.06, -1.89)R_E with magnetopause normal n being (0.85, -0.52, 0.003) and (0.82, 0.55, -0.17) in the GSE coordinates, respectively. Both events are tangential discontinuity-like structures with shear angles being 124° and 97° and convect tailward with the deHoffmann-Teller frame velocity V_HT of (-141.88, -215.47, 72.48) and (-100.26, 144.52, 20.90) (km/s), respectively, that form approximately 90° from n. The magnetic field configurations in both cases show great similarity with the same island width of -500 km and aspect ratio of -0.2.

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The SE Mediterranean margin of Spain is an extremely interesting area of synchronous interaction of tectonic, volcanic, evaporitic and mineralizing hydrothermal processes. This works tackles the multiple relations among these processes by the study of a specific and representative case: the ‘Jaroso Hydrothermal System’. The hydrothermal fluids were genetically linked with the late episodes of the Upper Miocene calc-alkaline and shoshonitic volcanism of the area. The ascent of the fluids was mainly controlled by the Palomares fault in Sierra Almagrera. In the shallow-marine basin of Las Herrerias, the movement of the acid solutions was controlled by both NNE-SSW and N150E normal faults and WNW-ESE wrench reverse faults. At least three mineralising stages were identified, although the particular formation of jarosite could be associated with both hypogenic and supergenic processes. We suggest that the multistage hydrothermal system of El Jaroso (Sierra Almagrera, Almería province, SE Spain), which is responsible for both the Jaroso ores (especially rich in jarosite) and the Las Herrerias sulfate-rich, shallow-marine laminites, could be exploited as a potential model with important implications for the exploration of Mars.

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To verify an additional ionization layer predicted in the equatorial ionosphere, topside ionograms obtained by the Planetary Plasma Sounder (PPS) system on-board the Ohzora (EXOS-C) satellite were analyzed. Based on the analysis of the PPS data of 8 passes in March and 11 passes in May, 1987, the ionization ledge observed in the local noon time period shows similar nature as it has been theoretically predicted for the F₃ layer by Balan and Bailey (1995). It was noted that some peaks of the ledge structure were located on the field line of higher latitude region than the field line of the crest of the equatorial anomaly.

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