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21.
The 1995 Northern Niigata Earthquake with special attention to a geopressured hydrothermal system 总被引：1，自引：0，他引：1
The 1995 Northern Niigata Earthquake of magnitude (M) 5.5 occurred at the eastern margin of the Niigata seismic gap and might have been a precursor of a large destructive earthquake. The anomaly areas in temperature, electrical conductivity and Cl- concentration of groundwater were approximately coincident with the area of the seismic intensity 6 on the Japan Meteorological Agency scale, and convincingly demonstrated the presence of a buried active fault beneath the epicentral area, as was suggested by a linear distribution of seismic intensity 6. These anomalies of groundwater were created by the expulsion of geopressured hydrothermal water along an active fault. Anomalies in local groundwater and hotspring systems associated with the earthquake and the proximity of the earthquake to the Niitsu oil field led to an interpretation that the earthquake might have been triggered by activity within the geopressured hydrothermal system. The accumulation of geopressured hydrothermal water in combination with high rock temperature might reduce fracture strength of the rock, and trigger earthquake occurrence. 相似文献
22.
Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA 总被引：3，自引：1，他引：2
Delwyn S. Oki William R. Souza Edward L. Bolke Glenn R. Bauer 《Hydrogeology Journal》1998,6(2):243-263
The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered
volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic
rocks and sediments are collectively known as caprock, because they impede the free discharge of groundwater from the underlying
volcanic aquifers. A cross-sectional groundwater flow and transport model was used to evaluate the hydrogeologic controls
on the regional flow system in southwestern Oahu. Controls considered were: (a) overall caprock hydraulic conductivity; and
(b) stratigraphic variations of hydraulic conductivity in the caprock. Within the caprock, variations in hydraulic conductivity,
caused by stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of groundwater
flow and the distribution of water levels and salinity. Results of cross-sectional modeling confirm the general groundwater
flow pattern that would be expected in a layered coastal system. Groundwater flow is: (a) predominantly upward in the low-permeability
sedimentary units; and (b) predominantly horizontal in the high-permeability sedimentary units.
Received, October 1996 Revised, August 1997 Accepted, September 1997 相似文献
23.
AbstractThe seasonal variation of land–atmosphere coupling strength has been examined using an extended series of atmospheric general circulation model (AGCM) simulations. In the Western Sahel of Africa, strong coupling strength for precipitation is found in April and May, just prior to and at the beginning of the monsoon season. At this time, heat and water fluxes from the surface are strongly controlled by land conditions, and the unstable conditions in the lower level of the troposphere, as induced by local land state, allow the surface fluxes to influence the variability of convective precipitation—and thus the timing of monsoon onset.Editor Z. W. KundzewiczCitation Yamada, T.J., Kanae, S., Oki, T., and Koster, R.D., 2013. Seasonal variation of land–atmosphere coupling strength over the West African monsoon region in an atmospheric general circulation model. Hydrological Sciences Journal, 58 (6), 1276–1286. 相似文献
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Abstract The Shinanogawa Seismic Belt in the Northern Fossa Magna, Honshu Island, Japan, extends along the Shinano River, bounding the Eurasian Plate and the Okhotsk Plate. The geopressured hydrothermal system occurs widely in the Northern Fossa Magna region. Many destructive earthquakes are related to the activity of this system in the Shinanogawa Seismic Belt. Expulsion of a geopressured hydrothermal system and rising from depth along an active fault triggers the occurrence of an earthquake and opens the fault as a pathway. Anomalous areas in temperature, electrical conductivity and Cl– concentration of groundwater trend north–east in a linear distribution, and convincingly demonstrate the presence of a buried active fault at the epicentral area of the destructive earthquake in the Shinanogawa Seismic Belt. The distribution of the major axis of the anomalous area in groundwater temperature shows a strong positive relationship with earthquake magnitude, which means that the distribution of this area may indicate the scale of earthquake fault. The linearly anomalous areas in groundwater temperature, resulting from the percolation of a geopressured hydrothermal system, that have no record of previous destructive earthquake are predicted to be areas where destructive earthquakes could occur in the future. Four potential earthquake areas are proposed and discussed in this paper, based on re-examination of active faults and seismicity in the Shinanogawa Seismic Belt. 相似文献