Damage to coastal villages due to the 1992 Flores Island earthquake tsunami

A field survey of the 1992 Flores Island earthquake tsunami was conducted during December 29, 1992 to January 5, 1993 along the north coast of the eastern part of Flores Island. We visited over 40 villages, measured tsunami heights, and interviewed the inhabitants. It was clarified that the first wave attacked the coast within five minutes at most of the surveyed villages. The crust was uplifted west of the Cape of Batumanuk, and subsided east of it. In the residential area of Wuring, which is located on a sand spit with ground height of 2 meters, most wooden houses built on stilts collapsed and 87 people were killed even though the tsunami height reached only 3.2 meters. In the two villages on Babi Island, the tsunami swept away all wooden houses and killed 263 of 1,093 inhabitants. Tsunami height at Riang-Kroko village on the northeastern end of Flores Island reached 26.2 meters and 137 of the 406 inhabitants were killed by the tsumani. Evidence of landslides was detected at a few points on the coast of Hading Bay, and the huge tsunami was probably formed by earthquake-induced landslides. The relationship between tsunami height and mortality was checked for seven villages. The efficiencies of trees arranged in front of coastal villages, and coral reefs in dissipating the tsunami energy are discussed.     

From the simplest chemical system to the natural one: garnet peridotite barometry

The available experimental data on garnet-bearing-assemblages for synthetic chemical systems (MAS, FMAS, CMAS) have been used to calibrate consistent models for the Al-solubility in orthopyroxene coexisting with garnet, on the basis of equilibrium reaction Py(opx) ? Py(gt). The alternative reaction En(opx)+MgTs(opx) ? Py(gt) is discarded as it yields larger a-posteriori uncertainties. To provide a reliable equation, directly applicable to natural garnet lherzolites, each successive synthetic-system calibration is tested against Mori and Green's (1978) natural-system reequilibration data. For the MAS system, an ideal solution model with constant ΔH°, ΔV° and ΔS° based on 12-oxygen structural formulae for aluminous pyroxenes yields the best fit (GPa, K), $${\text{25,134 + 9,941 }}P - 23.177{\text{ }}T{\text{ + }}RT{\text{ ln (}}X_{{\text{Al}}}^{TB'} {\text{) = 0}}$$ . The MAS synthetic-system calibration can be directly applied to the FMAS system by adding an empirical correction term (20,835 [X _Fe ^gt ]²) independent of either pressure and temperature. However, this correction term is not important because of the limited Fe content of mantle peridotites. When calcium is added to the MAS system, the equilibrium constant is calculated as: $$K_{{\text{CMAS}}} = {{[(1 - X_{{\text{Ca}}}^{M2} )^2 (X_{{\text{Al}}}^{TB'} )]} \mathord{\left/ {\vphantom {{[(1 - X_{{\text{Ca}}}^{M2} )^2 (X_{{\text{Al}}}^{TB'} )]} {[(1 - X_{{\text{Ca}}}^X )^3 (X_{{\text{Al}}}^Y )^2 ]}}} \right. \kern-\nulldelimiterspace} {[(1 - X_{{\text{Ca}}}^X )^3 (X_{{\text{Al}}}^Y )^2 ]}}$$ where M2 and TB′ are pyroxene sites and X and Y are garnet sites. Up to 5 GPa, X _Ca ^X ～ and the CMAS experimental data agree well with the MAS model, but for Yamada and Takahashi's (1983) higher pressure experiments (up to 10 GPa), this no longer holds. Indeed, the garnet solid solution does not behave ideally and an asymmetric regular solution model is needed for application to the deepest natural samples available (>7GPa). Calibration based on new high pressure data yields, $$\begin{gathered} \Delta G_{{\text{CMAS}}}^{XS} = (X_{{\text{Ca}}}^X )(1 - X_{{\text{Ca}}}^X )(0.147 - X_{{\text{Ca}}}^X ) \hfill \\ {\text{ }} \cdot {\text{(6,440,535 - 1,490,654 }}P{\text{)}} \hfill \\ \end{gathered}$$ . According to tests of the inferred solution model, the CFMAS system is a good analogue of natural systems in the pressure, temperature and composition ranges covered by the natural-system reequilibration data (up to 1,500° C and 4 GPa). Simultaneous application of this thermobarometer and of the two-pyroxene mutual solubility thermometer (Bertrand and Mercier 1985) to the phases of the garnet-peridotite xenoliths from Thaba Putsoa, Lesotho, yields a refined paleogeotherm for southern Africa strongly contrasting with previous results. The “granular” nodules yield a thermal gradient of about 8 K/km characteristic of a lithospheric-type environment, whereas the “sheared” ones show a lower gradient of about 1 K/km. This is a typical geotherm expected for a steady thermal state with an inflexion point at the depth of about 160 km corresponding to the lithosphere/asthenosphere boundary.     

Volatile elements in chondrites: metamorphism or nebular fractionation?

Three of the most highly metamorphosed meteorites of their respective classes, Shaw (LL7), Karoonda (C5), and Coolidge (C4), were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, and Zn. Comparison with data by Lipschutz and coworkers on artificially heated primitive meteorites shows that the natural metamorphism of meteorites cannot have taken place in a system open to volatiles. Shaw, metamorphosed at 1300°C for >10⁶ yr, is less depleted in In, Bi, Ag, Te, Zn, and Tl than Krymka heated at 1000°C for 1 week. Karoonda, metamorphosed at 600°C for many millennia, is less depleted in Bi and Tl than Allende heated at 600°C for 1 week.Data on primordial noble gases also show that the volatile-element patterns of ordinary and carbonaceous chondrites were established by nebular condensation, and changed little if at all during metamorphism. For enstatite chondrites, the evidence is still incomplete, but seems to favor a nebular origin of the volatile pattern.The general constancy of Tl/Rb, Tl/Cs and Tl/U ratios in terrestrial and lunar rocks suggests that loss of volatile metals such as Tl is rare during normal magmatism or metamorphism. Only impact melts show such loss with any frequency.     

Rain from shallow convective clouds—Maritime and continental

Work done initially with Y. Ogura and later by the present author was reviewed, with special emphasis on physical concepts in a cloud model. The present paper consists of two parts: a warm rain study and a graupel cloud model. The process of continuous improvement on physical ideas taken to formulate warm rain are described in the first part of this paper. It is shown that the number concentration of cloud droplets is the most sensitive factor in determining rainfall, and that there is a critical drop size distribution for initiation of rain. The second part describes a graupel cloud model and shows that graupel formation is the mechanism most likely to lead to precipitation from continental shallow convective clouds.     

Diurnal and seasonal variations of the oh (8, 3) airglow band and its correlation with OI 5577 Å

In this paper the results of OH (8,3) emission intensity and rotational temperature measurements made in the Brazilian sector (23°S) from 1972 to 1974 are presented. Diurnal variations of both the parameters are found to fall into distinct classes, showing significant seasonal effects. A correlative study with the OI 5577 Å emission measured simultaneously is also presented. It is shown that both the phase and amplitude of the major part of the mean nocturnal intensity variations of the two emissions can be explained by the density and temperature perturbations caused by the solar semidiurnal tide. The OH emission is found to increase slightly during magnetic disturbances.     

Mesospheric energy loss rates by OH and C2 emissions at 23°S

The nightglow OH(9,4) and O₂ atmospheric (0,1) band emission intensities and their rotational temperatures T(OH) and T(O₂), respectively, observed at Cachoeira Paulista (23° S, 45°W), Brazil, during the period from October 1989 to December 1990, have been analyzed to study the nighttime mesospheric energy loss rates through the radiations from the vibrationally excited OH* and electronically excited O*₂ bands. The total emission rates of the OH Meinel bands, O₂ atmospheric (0,0) and O₂ infrared atmospheric (¹_g) bands were calculated using reported data for the relative band intensities and . It was found that there is a minimum in equivalent energy loss rate by the OH* Meinel bands during December/January (equivalent energy loss rate of 0.39 K/day*, where day* means averaged over the night) and maximum in equivalent energy loss rate during September (equivalent energy loss rate of 0.98 K/day*). Energy loss rate by the O*₂ radiation, on the other hand, is weaker than that by the OH* Meinel bands, showing equivalent energy loss rates of 0.12 K/day* and 0.22 K/day* during January and September, respectively.     

Meteoritic material at five large impact craters

Sixteen crater samples were analyzed by radiochemical neutron activation analysis for Ge, Ir, Ni, Os, Pd and Re. Two impact melt rock samples from Clearwater East (22 km) showed strong, uniform enrichments in all elements except Ge, corresponding to 7.4% C1 chondrite material. Interelement ratios suggest that the meteorite was a C1 (or C2) chondrite, not an iron, stony iron, or chondrite of another type. An Ivory Coast tektite (related to the 10 km Bosumtwi crater) was enriched in Ir + Os and Ni to about 0.04 and 1.6% of C1 chondrite levels, but in the absence of data on country rocks, the meteorite cannot yet be characterized.Impact melt rock samples from Clearwater West (32km), Manicouagan (70km), and Mistastin (28 km) showed no detectable meteoritic component. Upper limits, as Cl chondrite equivalent, were Os ≤ 2 × 10^?3% (~0.01 ppb), Ni ≤ 2 × 10^?1% (~20ppm). Possible causes are high impact velocity and/or a chemically inconspicuous meteorite (achondrite, Ir,Os-poor iron or stony iron). However, a more likely reason is that some fraction of the impact melt remains meteorite-free, especially at craters with central peaks.Clearwater East is the first terrestrial impact crater found to be associated with a stony meteorite. Apparently the consistent absence of stony projectiles at small craters (< 1 km diameter) reflects their destruction in the atmosphere, as proposed by Öpik.     

A THEORETICAL STUDY ON THE MULTIPLE EQUILIBRIA OF TROPICAL ATMOSPHERE AND THEIR RELATION TO THE ONSET OF THE SUMMER MONSOON

Multiple equilibria and their stability in tropical atmosphere are investigated through β-plane barotropic models with consideration of heating and dissipation. We have derived the solutions of the model equations corresponding to the multiple equilibria or the steady flows first, and then establish the criteria for the stability of steady flow by use of the Liapunov direct Method. When these criteria are applied to the solutions of equilibria obtained, stable flows, which are closely related to the different patterns of quasi-stationary circulation in the tropical region, are found. The configurations of these stable flows and the shift between two of them as season changes provide quite reasonable explanations to many fundamental problems of tropical circulation features such as the catastrophe mechanism of the onset and the break-active cycle of the Asian summer monsoon. It follows that the onset or the abrupt transition of the Asian summer monsoon could be attributed to the multiple equilibrium property of the tropical circulation resulted from the advective nonlinearity, which provide another explanation among others.     

Dynamical structure and wind-driven upwelling in a summertime anticyclonic eddy within Funka Bay,Hokkaido, Japan

We conducted hydrographic observations in 2002 to investigate the anticyclonic eddy that emerges every summer in Funka Bay, Hokkaido, Japan, and elucidate dynamical structure and wind-driven upwelling within the eddy. The anticyclonic eddy has a vertical scale of 32 m and is characterized by a strong baroclinic flow and a sharp pycnocline with a concave isopycnal structure. The sharp pycnocline occurs below a warm and relatively low-salinity water termed summer Funka Bay water (FS), which is formed by heating from solar radiation and dilution from river discharge in summertime Funka Bay. Flow of the anticyclonic eddy rotates as a rigid body at each layer, and the horizontal scale and rotation period of the eddy in the surface layer are about 15 km and 2.2 days, respectively. The dynamical balance of the anticyclonic eddy is well explained by the gradient flow balance. The contribution of centrifugal force to the gradient flow balance is about 27%. Therefore, the effect of the nonlinear term associated with centrifugal force cannot be neglected in considering the dynamics of the anticyclonic eddy in summertime Funka Bay. In addition, upwelling of subsurface water was observed in the surface layer of the central part of the eddy. The formation mechanism of this upwelling is consistent with interaction between horizontal uniform wind and the eddy. This upwelling is driven by upward Ekman pumping velocity related to the horizontal divergence of Ekman transport. In summertime Funka Bay, there are two wind effects that affect the anticyclonic eddy: a decay effect of the upwelling of subsurface water resulting from horizontal uniform wind (mainly northwesterly wind), and a maintenance or spin-up effect of horizontal non-uniform wind (mainly southerly–southeasterly seasonal wind) with negative wind stress curl.