共查询到19条相似文献，搜索用时 140 毫秒
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介绍了重庆近代4次较强地震的情况,并根据旱震关系研究和短期临震气象要素5项指标异常研究,系统地检验了1989年的重庆渝北统景地震、1997年的重庆荣昌许溪地震和1999年的重庆荣昌县城地震震前气象要素异常情况。最后提出了建立全国性的,特别是地震高危地区的地震气象要素异常前兆预警系统设想。 相似文献
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随着农业机械化程度的提高，不少农户家庭也有了农用柴油机，然而他们却没有掌握维修知识，一些出故障的前兆也不知道。下面介绍几种发生重大故障的前兆： 相似文献
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拖拉机出现故障前往往会表现出特有的现象，这也可称作前兆这些前兆一般都具有可听、可闻、可见、可触摸或可测量的性质，概括起来有以下6种： 相似文献
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<正>自2008年以来,我国川滇地区就发生了三次强烈地震,特别是2008年5月12日发生在四川汶川的8.0级特大地震,让人终生难忘。频繁的强烈地震在给人们的生命财产带来巨大损失的同时,也给震区人们的心理留下了深深的创伤。事实上,地震的发生都是有前兆的,这些前兆之中的奥妙,有些还是可以利用化学知识来加以解释的。地震发生的一个重要前兆就是地下水的异常。对此,我国民间早就流传着这样的顺口溜: 相似文献
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2008年5月12日,是中国人民不可磨灭,悲伤并难以忘怀的日子!汶川大地震,触动着每个中国人的心灵。灾难,难道真的就不能预知与预防吗？隔行如隔山,地震究竟能不能预防,笔者不敢肯定。但在少年时期,自然课老师告诉我们,地震是可以预知与预防的,因为地震发生是有前兆的。 相似文献
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<正> 柴油机在发生重大故障之前,一般都会产生或轻或重的反常现象,即故障前兆。掌握故障前兆,对于预防或减轻重大机械事故非常必要。 (1)烧瓦的前兆 柴油机工作中,转速突然自行降低,负荷加重,发动机冒 相似文献
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柴油机在发生重大故障之前,大都会产生反常现象即故障前兆。掌握下列故障前兆,有助于预防重大机械事故。1．烧瓦的前兆。柴油机工作中转速突然降低,发动机冒黑烟,机油压力下降,曲轴箱内发出“唧唧”干摩擦声, 相似文献
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烧瓦的前兆。柴油机工作中转速突然降低,负荷加重,发动机冒黑烟,机油压力下降,曲轴箱内发出“唧唧”的干磨擦声,这是烧瓦的前兆。遇到这种情况应立即停机;否则会进一步加重轴瓦的磨损,轴颈表面抓粘迅速扩展,轴瓦与轴颈很快就会粘结死,发动机熄火。粘缸的前兆。粘缸一般在柴油机 相似文献
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During the period 1973 to 1991 the interval between eruptions from a periodic geyser in Northern California exhibited precursory variations 1 to 3 days before the three largest earthquakes within a 250-kilometer radius of the geyser. These include the magnitude 7.1 Loma Prieta earthquake of 18 October 1989 for which a similar preseismic signal was recorded by a strainmeter located halfway between the geyser and the earthquake. These data show that at least some earthquakes possess observable precursors, one of the prerequisites for successful earthquake prediction. All three earthquakes were further than 130 kilometers from the geyser, suggesting that precursors might be more easily found around rather than within the ultimate rupture zone of large California earthquakes. 相似文献
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Some large earthquakes display low-frequency seismic anomalies that are best explained by episodes of slow, smooth deformation immediately before their high-frequency origin times. Analysis of the low-frequency spectra of 107 shallow-focus earthquakes revealed 20 events that had slow precursors (95 percent confidence level); 19 were slow earthquakes associated with the ocean ridge-transform system, and 1 was a slow earthquake on an intracontinental transform fault in the East African Rift system. These anomalous earthquakes appear to be compound events, each comprising one or more ordinary (fast) ruptures in the shallow seismogenic zone initiated by a precursory slow event in the adjacent or subjacent lithosphere. 相似文献
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A 24 percent precursory change in apparent electrical resistivity was observed before a magnitude 3.9 earthquake of strike-slip nature on the San Andreas fault in central California. The experimental configuration and numerical calculations suggest that the change is associated with a volume at depth rather than some near-surface phenomenon. The character and duration of the precursor period agree well with those of other earthquake studies and support a dilatant earthquake mechanism model. 相似文献
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A large precursory change in seismic body-wave velocities occurred before the earthquake in San Fernando, California. The discovery that this change is mainly in the P-wave velocity clearly relates the effect to the phenomenon of dilatancy in fluid-filled rocks. This interpretation is supported by the time-volume relation obtained by combining the present data with the data from previous studies. The duration of the precursor period is proportional to the square of an effective fault dimension, which indicates that a diffusive or fluid-flow phenomenon controls the time interval between the initiation of dilatancy and the return to a fully saturated condition which is required for rupture. 相似文献
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Ground-water radon anomaly before the kobe earthquake in Japan 总被引：1，自引：0，他引：1
Igarashi G Saeki S Takahata N Sumikawa K Tasaka S Sasaki Y Takahashi M Sano Y 《Science (New York, N.Y.)》1995,269(5220):60-61
Radon concentration in ground water increased for several months before the 1995 southern Hyogo Prefecture (Kobe) earthquake on 17 January 1995. From late October 1994, the beginning of the observation, to the end of December 1994, radon concentration increased about fourfold. On 8 January, 9 days before the earthquake, the radon concentration reached a peak of more than 10 times that at the beginning of the observation, before starting to decrease. These radon changes are likely to be precursory phenomena of the disastrous earthquake. 相似文献
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Chloride (Cl(-)) and sulfate (SO(4)(2-)) ion concentrations of ground water issuing from two wells located near the epicenter of the Kobe earthquake in Japan fluctuated before the disastrous magnitude 7.2 event on 17 January 1995. The samples measured were pumped ground water packed in bottles and distributed in the domestic market as drinking water from 1993 to April 1995. Analytical results demonstrate that Cl(-)and SO(4)(2-) concentrations increased steadily from August 1994 to just before the earthquake. Water sampled after the earthquake showed much higher Cl(-) and SO(4)(2-) concentrations. The precursory changes in chemical composition may reflect the preparation stage of a large earthquake. 相似文献
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Rupture in individual earthquakes apparently is limited to regions between bends in faults. This is illustrated for eight events that have occurred since 1966. A model based on geometric concepts describes why this is so and clarifies earlier ideas of "asperities" and "barriers" used to explain earthquake initiation and termination processes. Because of their importance in the rupture process, bend zones should be monitored for precursory effects. 相似文献
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对汶川地震中汉中地区农房的震害特征进行了调查分析,结合震害主要从增加强度,增强连接等提出提高生土结构抗震能力的建议。 相似文献
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Recent earthquake prediction research in Japan 总被引：1，自引：0，他引：1
Mogi K 《Science (New York, N.Y.)》1986,233(4761):324-330
Japan has experienced many major earthquake disasters in the past. Early in this century research began that was aimed at predicting the occurrence of earthquakes, and in 1965 an earthquake prediction program was started as a national project. In 1978 a program for constant monitoring and assessment was formally inaugurated with the goal of forecasting the major earthquake that is expected to occur in the near future in the Tokai district of central Honshu Island. The issue of predicting the anticipated Tokai earthquake is discussed in this article as well as the results of research on major recent earthquakes in Japan-the Izu earthquakes (1978 and 1980) and the Japan Sea earthquake (1983). 相似文献