A new method for determination of a wave-ray trace based on tsunami isochrones
A new method for the tsunami wave ray construction is proposed. It is based on isochrones that are built with the use of the wave travel times to a tsunami source. The wave ray approximation is determined as a broken line passing through intersection points of identical time isochrones from two supplementary dot sources. The method was tested on different types of the bottom relief. 1. Methods for the wave ray construction There are a few different methods for the wave rays determination in a non-homogeneous area. The first way is constructing a ray by a numerical solution to the differential equations [1]
Directivity of tsunami generated by subduction zone sources
In a subduction zone, a tsunami source is usually situated above the continental bottom slope. Due to the wave refraction, the opposite slope of a deep water trench works like an optical lens for tsunami waves. The tsunami propagation process is studied using the wave-ray approximation. The tsunami amplitude reduc- tion rate strongly depends on a relative (regarding a trench) location of the initial surface displacement. If the source boundary expands closer to a deep trench axis, then the initially circled front line of the leading tsunami wave will be formed into almost a at shape after passing a trench. The same kind of tsunami behavior can be observed when a wave is generated by a submarine mudslide on a trench slope. A number of hypothetic tsunamis were simulated in the Alaska-Aleutian and in the Kuril{Kamchatka subduction zones. Some locations of possible tsunami sources are estimated as most dangerous for the Hawaiian population and infrastructure. For the most part the tsunamigenic earthquakes occur at subduction zones. The presence of a deep water trench is the main characteristic feature of such a zone. The initial ocean surface displacement (a tsunami source) and earthquake epicenters are mainly located above the continental bottom slope. In Figure 1, the bottom relief (1) of the Kuril{Kamchatka region with historical tsunami source locations is presented (2). The depth at the deep water trench axis is approximately twice as great as an average depth of the Pacic
Geological, mineralogical and chemical characterization of Devonian kaolinite-bearing sediments for further applications in the ceramic (tiles) industry in La Paz, Bolivia
Clay minerals are widely distributed in Bolivia; among them, illitic clays are most common in the Altiplano where they are mined for use in the ceramic industry that has been growing in the last few years. In addition to illitic sediments, kaolinitic sediments have been recently discovered in sedimentary units in the Bolivian Altiplano. Residual ball clay occurrences in Devonian sedimentary units were studied as part of this work. Geological mapping and geophysical studies (ERT and GPR) were done for better understanding the origin of the deposits and were part of a preliminary study of the mineral potential to define the relationship with the host rock. Chemical and mineralogical techniques such as X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma analyses were performed in samples from the studied area to verify the presence of kaolinite. Atterberg limits and behaviour of the raw material in ceramic specimens supported by chemical analyses show that this material is suitable for manufacturing tile ceramics. This study provides fundamental knowledge for deposit exploitation and future generation of an alternative source of employment for the inhabitants of Micaya.