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| index | Vol. 49 | 1 | 2/3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Japanese Index | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Rockslide-debris Avalanche of May 18, 1980, Mount St. Helens Volcano, Washington
Harry GLICKEN
1998
vol. 49 (2/3) P. 55-106, 32figs., 5table, 2 plates
Keywords: Mount St. Helens, 1980 eruption, volcano, debris avalanche, Cascade Mountain, Washington, debris avalanche hummocks, grain flow, blast surge, pyroclastic current, pyroclastic flow
Abstract: The Mount St. Helens rockslide-debris avalanche moved as three slide blocks. Slide block I occurred in association with a magnitude 5.1 earthquake at 8:32 a.m. Pacific Daylight Time (PDT) on May 18, 1980. An exploding cryptodome burst through slide block K to produce thegblast surge.hSlide block L consisted of many discrete failures carried along by continuing pyroclastic currents generated from the exploding cryptodome. The hummocky 2.5-km3 debris-avalanche deposit consists of block facies (pieces of the pre-eruption mountain transported relatively intact) and matrix facies (a mixture of rocks from the old mountain and cryptodome dacite). Block facies is divided into five lithologic units. Matrix facies was derived from the explosively generated current of slide block L as well as from disaggregation and mixing of debris-avalanche blocks.
@The debris avalanche dilated at the mountain rather than during transport. The debris-avalanche flow can be considered a grain flow, where particles - either debris-avalanche blocks or the clasts within the blocks - collided and created dispersive stress normal to the movement of material. The dispersive stress preserved the dilation of the material and allowed it to flow.
Eastern Asia Natural Hazards Mapping Project
Hirokazu KATO
1998
vol. 49 (2/3) P. 107-123, 16figs.
Keywords: Eastern Asia, natural hazard, disaster, mitigation, hazard mapping
Abstract: Asian countries have been severely damaged by various natural hazards because of their complicated and disastrous geo-environment. Eastern Asia Natural Hazards Mapping Project was proposed by the Geological Survey of Japan in 1992 and implemented in1994 to focus on the geological hazards in eastern Asia. It aims to compile small-scaled (1:5,000,000) hazards maps and relevant databases. Following conferences were held in succession in order to promote the project : International Forum for Natural Hazards Mapping in June 1993, International Meeting on Eastern Asia Natural Hazards Mapping Project in May 1994, First Workshop on Eastern Asia Natural Hazards Mapping Project in September 1994, International Symposium on Asian Natural Disasters and Hazards Mapping in September 1994, Second Workshop on Eastern Asia Natural Hazards Mapping Project in September 1995, Third Workshop on Eastern Asia Natural Hazards Mapping Project in August 1996, Symposium on Eastern Asia Natural Hazards Mapping in August 1996, International Symposium on Geology for Geohazards Mitigation in Asia in February 1997. The outline of the Hazards Map has been established throughout these conferences. At first, geological maps were presented showing geological background. Identified hazards such as earthquake hazard, volcanic hazard, landslide, coastal erosion/deposition, land subsidence, karst collapse and seawater intrusion are expressed by respective symbols on the geological map. The distribution of densely populated areas is shown on the same map in order to evaluate the vulnerability by natural hazards qualitatively. Detailed hazards data are all described on the data sheets on which the relevant databases have been developed. The index of several kinds of published maps has also been developed, and will be distributed among concerned people.
Environmental geological mapping and some problems in Korea
Gyo-Cheol JEONG and Won-Young KIM
1998
vol. 49 (2/3) P. 125-126, 1fig., 2tables
Keywords: Korea, environmental geology, land-use geological hazard
Abstract: Environmental geological map including various thematic maps such as hazard geotechnical map, hydrogeological map, geochemical map, quaternary geological map, material property map and construction material map etc. plays important roles in optimal land-uses in terms of foundation engineering, surface and ground water, natural and artificial hazards and construction material etc. (refer to Fig.1).
@Environmenta1 geology in Korea is, as elsewhere, an interdisciplinary field. As such, it is being utilized for site selection of radioactive waste disposal and underground space development, water resources development and optimal land-use plan for the future etc. Environmental geological mapping project in Korea has been conducted by Korea Institute of Geology, Mining and Materials (KIGAM). Up to now, applied geological maps (8 areas), scaled in l:25000, including various thematic maps such as engineering geological map, slope class map, soil and land resources map, drainage density map and documentation map, and hydrogeological maps (7 areas) were published by KIGAM. Recently environmental geologic map, (Kimpo-Ilsan area) at 1:25000 scale, consisting of basment level map, groundwater level map, topographic map, soil map, relief map and slope map were published in 1993 by KIGAM.
@Environmental geological mappings for topics and problems represent only the tip of the iceberg. Nevertheless, they might shed some light on the existing environmental problems which must be resolved.
A review of catalogues of Chinese Earthquakes
Zhi-xian YANG
1998
vol. 49 (2/3) P. 127-130, 4tables
Keywords: China, earthquake catalogue, magnitude scale
Abstract: In the past a decade, Catalogues of Chinese earthquakes with higher authority and being used widely by seismologists in China are:
@1. Gu Gong-xu, 1983, Catalogue of Chinese earthquakes;
@2. Min Zi-qun, 1988, Simple catalogue of Chinese earthquakes;
@3. Xie Yu-suou, 1989, Catalogue of Chinese earthquakes (M 4.7) from 1900-1980 with uniform magnitudes;
@4. Min Zi-qun, 1995, Catalogue of Chinese historical strong earthquakes.
@Earthquakes occured pre-1900 are mainly from historical materials.
Since 1950's, two major compilings of historical materials finished in 1956 and 1983-1987 separately resulted in two chronicles, two volumes for the first and five volumes for the second. The magnitudes are converted from the max. intensity. These magnitudes, by convention, are connected with surface wave magnitudes to be used. But it is clear that they have no any strict seismological conception yet.
@The period 1900-1962 is early instrumental record era. Magnitudes of all earthquakes occured in this period, in principle, are determined by Chinese own magnitude scale. It seems that further detail description about this in the explanatory remarks of early catalogue is less. In fact, perhaps, it is complicated, because just a few seismic stations existed at that time in China.
@The period after-1963 is modern instrumental era. All surface wave magnitudes are determined by Beijing Baijiatan-seismic station magnitude formula, which is different from that LASPEL recommended to global. Beijing Baijiatan magnitudes have a systematic over-estimation of 0.2 magnitude unit.
@Catalogues of Chinese earthquakes need to be connected with global seismic data, to unify seismic paramers in these catalogues becomes a urgent task, which will be considered in our research plan of GSHAP.
Landslide database of Indonesia
Yousana O. P. SIAGIAN
1998
vol. 49 (2/3) P. 131-134, 2tables
Keywords: Indonesia, landslide, database, susceptibity
Abstract: Topographic, geologic and rainfall factors of Indonesia show her Archipelago having high potential of landslide hazard. Based on the frequent occurrences and the loss of human life, landslide hazard is one of the major geologic hazards in Indonesia.
@All obtained data from the investigation are recorded on the landslide database in order to facilitate the monitoring of landslide hazard status, and to support the DEG scientists in landslides research and landslide mitigation.
Geological hazards maps of Indonesia
Irwan BAHAR
1998
vol. 49 (2/3) P. 135-142, 10figs., 1table
Keywords: Indonesia, geological hazard map, landslide susceptibility map, seismotectonic map, volcanic hazard map
Abstract: Some geological hazards maps and related data of Indonesia are introduced here. They include base map, landslide susceptibility map, seismotectonic map, volcanic hazard map and related geological hazard information.
