Seismotectonic Reactions to the Arc-continent Convergence in Central Philippines

Abstract. High seismic activity in the Philippines originates from tectonic convergence related to surface and subsurface seismotectonic features. Based on earthquake data, the archipelago can be divided into the seismically-active Philippine Mobile Belt and the aseismic North Palawan Block. The latter represents a rifted continental fragment of the Eurasian margin that juxtaposed with the rest of island arc units in central Philippines. Earthquake hypocenter plots on planar and in vertical profiles show that the seismic events are associated with known seismotectonic features. In addition, data suggest that the collision zone between the North Palawan Block and the Philippine Mobile Belt is characterized by a decreased amount of hypocenters at > 100 km depths. Although field evidence favors the presence of a subducted slab or slabs beneath western central Philippines, these are difficult to image using the present seismicity distribution dataset.     

Experimental engineering procedure for the recovery of liquid water from the atmospheric vapor content

Summary It is proposed that liquid water be recovered from the atmosphere through a partial duplication of natural moist convection processes within an experimental piece of equipment in which certain of the actions could be protected and enhanced. No source of driving energy other than the automatic release of latent heat of condensing water vapor is envisioned. Various problems of a scientific and engineering nature that arise are enumerated and discussed in a preliminary fashion.     

Comparative urbanization project for the Asian pacific region

This short article outlines the objectives, organization, research frame and content areas of a comparative urbanization project which will start in 1981. The project involves a total of nine national teams each of which is composed of three or more experts from the fields of urban geography, city and regional planning, demography, development economics and other related disciplines. One unique feature of the project is that each of the countries covered will be researched on by its own local researchers. And, the organizer tries to get at least one government official involved, in his personal capacity, as a team member, to get better insight and interpretation of official policies and objectives regarding urbanization. The responsible persons of the national teams and the time table of the project have also been included in this article.     

Alpha emitters in a coral from Bikini lagoon: A testimony to nuclear blasts in the Western Pacific

In the years between 1946 and 1958, Bikini Atoll was the site of a series of nuclear device tests which led to the contamination of the calcium-carbonate tests of organisms, including those of corals. Alpha emitters and other radio-nuclides concentrated in these tests. The purpose of our study was to determine where in these test-alpha-emitters concentrated.Petrography of ultra thin sections, in conjunction with solid state alpha-track detectors, shows that it is possible to assign the alpha activity to different parts of the fabric within a coral. The application of this technique to a coral,Favites virens, from the lagoon of Bikini Atoll showed that the theca, septa and dissepiments of the coral skeleton contain very low concentrations of alpha emitters. By contrast, high concentration of alpha emitters occur in damaged parts of the coral. Some of these damaged areas contain cryptocrystalline calcium carbonate, different organisms (algae and/or bryozoan-like tests) and skeletal debris. High concentrations of alpha emitters are associated with the cryptocrystalline calcium carbonate (up to 3000 pCi/g), the skeletal debris (up to 550 pCi/g), bryozoan-like material, and algae (up to 700 pCi/g).

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On the period variability of GP andromedae

The present paper deals with the pulsation period variability of the high-amplitude δ Scuti star GP Andromedae using a data set covering a time base of 26.9 years. The possibility of a periodic component (reflecting the light-time effect induced by a hypothetic binarity) in the O-C curve is inferred. The presence of this periodicity in the period variation of GP And leads to a diminution of the discrepancy between predicted and observed relative period change rates. The hypothesis of the existence of an unseen companion is discussed. The statistical analysis of the final O-C residuals distribution, indicates their normal or close to normal character. This revised version was published online in July 2006 with corrections to the Cover Date.     

Estimation of in-situ hydraulic diffusivity of rock masses

A method of estimating in-situ hydraulic diffusivity of rock masses by means of well-injection history and frequency of induced seismicity is presented. The method is based on the diffusion of injected fluid from a spherical cavity in a poroelastic half-space and the effective stress theory, as proposed byTerzaghi (1925, 1936) andHubbert andRubey (1959). Application of the method to two different regions, one in western New York and the other in Japan, resulted in estimated diffusivities of the order 10³ and 10⁴ cm²/sec, respectively. These values lie within the range of published estimates of in-situ diffusivity by other means, a summary of which is presented in tabular form. The calculated diffusivities suggest that the characteristic time of fluid diffusion is close to 0.1, rather than unity, as is sometimes assumed in the literature.     

The effect of dust on Tremaine–Weinberg measurements

We investigate the effect of dust on the observed rotation rate of a stellar bar. The only direct way to measure this quantity relies on the Tremaine & Weinberg (TW) method which requires that the tracer satisfies the continuity equation. Thus, it has been applied largely to early-type barred galaxies. We show using numerical simulations of barred galaxies that dust attenuation factors typically found in these systems change the observed bar pattern speed by 20–40 per cent. We also address the effect of star formation on the TW method and find that it does not change the results significantly. The results presented here suggest that applications of the TW method can be extended to include barred galaxies covering the full range of Hubble type.     

Projection of lightning over South/South East Asia using CMIP5 models

Physical phenomena observed before strong earthquakes have been reported for centuries. Precursor signals, which include radon anomalies, electrical signals, water level changes and ground lights near the epicenter, can all be used for earthquake prediction. Anomalous negative signals observed by ground-based atmospheric electric field instruments under fair weather conditions constitute a novel earthquake prediction approach. In theory, the abnormal radiation of heat before an earthquake produces fair weather around the epicenter. To determine the near-epicenter weather conditions prior to an earthquake, 81 global earthquake events with magnitudes of 6 or above from 2008 to 2021 were collected. According to Harrison's fair weather criteria, in 81.48% of all statistical cases, the weather was fair 6 h before the earthquake; in 62.96% of all cases, the weather was fair 24 h before the event. Moreover, most of these cases without fair weather several hours before the earthquake were near the sea. Among the 37 inland earthquakes, 86.49% were preceded by 6 h of fair weather, and 70.27% were preceded by fair weather for 24 h. We conclude that the weather near the epicenter might be fair for several hours before a strong earthquake, especially for inland events.