共查询到20条相似文献,搜索用时 206 毫秒
1.
Porepresureindepboreholes:ItsmeasurementandrelationwithseismicactivitiesJIANLIGAO(高建理)SHIZONGSUN(孙世宗)JIANMINDING(丁健民)GU... 相似文献
2.
StudyoftheanomalyofseismicfractalspectrumbeforestrongearthquakesLINGRENZHU1)(朱令人)SHIYONGZHOU1)(周仕勇)MALINGYANG1)(杨马陵)HAIT... 相似文献
3.
SomegeologicsignaturesoffaultcrepinthecontinentalareaofChinaHONGFAXIANG(向宏发)SHUNMINGUO(虢顺民)WANXIAZHANG(张晚霞)BINGLIANGZHAN... 相似文献
4.
TheanomalousreactionsofthegeomagnetichorizontalfieldtransferfunctionsbeforeTangshanearthquakeSHAOJINGGONG(龚绍京)HUARANCHEN(... 相似文献
5.
TheidentificationandcriteriaofshorttermseismicitygapbeforeagreatearthquakeJINGQUANCAO(曹井泉)JIALINSUN(孙加林)YIYANG(杨毅)Seismol... 相似文献
6.
Robust inversion analysis of local gravity anomalies caused by geological dislocation model of faults 总被引:5,自引:0,他引:5
RobustinversionanalysisoflocalgravityanomaliescausedbygeologicaldislocationmodeloffaultsJIANLIANGHUANG(黄建梁)CHONGYANGSHEN(申... 相似文献
7.
Studyofa3DseismicgapYUANQINGZHU1)(朱元清)CONGJUNXIA1)(夏从俊)GETUZUOLI2)(左力格图)HUIMINLI1)(李慧民)1)SeismologicalBureauofShanghai,... 相似文献
8.
PhysicalbackgroundonestimatingbvalueWEIQIONGHUANG(黄玮琼)WENXIANGLI(李文香)InstituteofGeophysics,StateSeismologicalBureau,Beijin... 相似文献
9.
SeismicactivityandactivefaultsinHuailaibasinPEIDEWANG(王培德)YUHONGTIAN(田玉红)CHUNLAILI(李春来)YUNTAICHEN(陈运泰)InstituteofGeophys... 相似文献
10.
scattering and refracting of plane strain wave by a cylindrical inclusion in fluidsaturated soils 总被引:1,自引:0,他引:1
ScateringandrefractingofplanestrainwavebyacylindricalinclusioninfluidsaturatedsoilsYAYUANHU(胡亚元)LIZHONGWANG(王立忠)YUNMINCH... 相似文献
11.
IntroductionMaximumentropyspectralmethod(MEM)(Burg,1972)hadbeenamethodusuallyusedinstudyingtheseismicityanditsmainpurposeistofindthedominantspectrainthelong-termseismicityprocessesinthepastyears(Zhu,1985).Inthispaper,themethodisappliedtostudywhethertherearesomespecialspectraofseismicityinsomespecificstagesinearthquake-generatingprocesses.Sowestudyseparatelythenormalandabnormalstageofearthquakeactivity,whoseactiveprocessisregardedasstablestochasticprocess,inordertofindtheirspectracharactersan… 相似文献
12.
华北地区历史强震活动频繁, 但自1998年张北6.2级地震后至今6级以上地震平静近22年。 大家对该区域未来6级以上地震危险趋势非常关注, 且有不同观点。 本文分析了该区6级以上地震活跃—平静周期性, 运用小波变换技术对周期成分进行了定量计算; 对比研究了活跃期与平静期之间的过渡阶段(本文称其为过渡幕)地震活动特点及其持续时间; 从1999—2018年地震应变释放率与第Ⅲ、 第Ⅳ活跃期、 第3平静期和第Ⅳ活跃期内第3、 第4平静幕的对比、 平静幕持续时间的统计特征、 当前华北地区显著的5级地震平静以及该区6级和7级以上地震前5级以上地震活动状态等方面进行了研究。 结果显示, 支持当前华北地区进入平静期的依据相对较多。 相似文献
13.
We report results from a detailed study of seismicity in central Kamchatka for the period from 1960 to 1997 using a modified
traditional approach. The basic elements of this approach include (a) segmentation of the seismic region concerned (the Kronotskii
and Shipunskii geoblocks, the continental slope and offshore blocks), (b) studying the variation in the rate of M = 4.5–7.0 earthquakes and in the amount of seismic energy release over time, (c) studying the seismicity variations, (d)
separate estimates of earthquake recurrence for depths of 0–50 and 50–100 km. As a result, besides corroborating the fact
that a quiescence occurred before the December 5, 1997, M = 7.9 Kronotskii earthquake, we also found a relationship between the start of the quiescence and the position of the seismic
zone with respect to the rupture initiation. The earliest date of the quiescence (decreasing seismicity rate and seismic energy
release) was due to the M = 4.5–7.0 earthquakes at depths of 0–100 km in the Kronotskii geoblock (8–9 years prior to the earthquake). The intermediate
start of the quiescence was due to distant seismic zones of the Shipunskii geoblock and the circular zone using the RTL method, combining the Shipunskii and Kronotskii geoblocks (6 years). Based on the low magnitude seismicity (M≥2.6) at depths of 0–70 km in the southwestern part of the epicentral zone (50–100 km from the mainshock epicenter), the quiescence
was inferred to have occurred a little over 3 years (40 months) before the mainshock time and a little over 2 years (25 months)
in the immediate vicinity of the epicenter (0–50 km). These results enable a more reliable identification of other types of
geophysical precursors during seismic quiescences before disastrous earthquakes. 相似文献
14.
天山地块强震活动的时空特征研究 总被引:3,自引:0,他引:3
通过对天山地块近百年地震活动时空特征分析表明: ① MS≥7.0地震沿块体边界成带分布, 南边界带强于北边界带, 南、 北边界带的西部强于东部, 南天山西段是地震活动水平最高、 复发周期最短、 强震序列类型最复杂、 地震危险性最大的地区; ② 地震活动在时间上显示出准周期性, 表现为MS≥7.0地震具有活跃与平静的交替性及5级以上地震活动度曲线的起伏变化; 最大熵谱计算地震活动度的显著周期为40年, 小波分析给出40年左右周期系数的时间曲线表明, 7级以上地震都发生在曲线由最高值至最低值的下降段, 而上升段为强震的平静期; ③ 在强震活跃期及平静期, 中强以上地震(MS≥5.0)在块体的不同部位(地块南、 北边界带及块体内部)的分布状态和活动水平存在明显的差异, 在活跃期南、 北边界带中强以上地震的集中性和成带性强, 且彼此活动水平差异小, 但与块体内部差异大; 而在平静期南、 北边界带的活动水平差异大, 块体内部地震活动显著增强; ④ 在活跃期, 天山地块南、 北边界带强震活动存在一定的呼应关系, 当一个边发生强震后, 另一边在数天至数年也存在发生强震的可能。 相似文献
15.
D. Shanker H. N. Singh H. Paudyal A. Kumar A. Panthi V. P. Singh 《Pure and Applied Geophysics》2010,167(6-7):655-666
A long-range correlation between earthquakes is indicated by some phenomena precursory to strong earthquakes. Most of the major earthquakes show prior seismic activity that in hindsight seems anomalous. The features include changes in regional activity rate and changes in the pattern of small earthquakes, including alignments on unmapped linear features near the (future) main shock. It has long been suggested that large earthquakes are preceded by observable variations in regional seismicity. Studies on seismic precursors preceding large to great earthquakes with M ≥ 7.5 were carried out in the northeast India region bounded by the area 20°–32°N and 88°–100°E using the earthquake database from 1853 to 1988. It is observed that all earthquakes of M ≥ 7.5, including the two great earthquakes of 1897 and 1950, were preceded by abnormally low anomalous seismicity phases some 11–27 years prior to their occurrence. On the other hand, precursory time periods ranged from 440 to 1,768 days for main shocks with M 5.6–6.5 for the period from 1963 to 1988. Furthermore, the 6 August, 1988 main shock of M 7.5 in the Arakan Yoma fold belt was preceded by well-defined patterns of anomalous seismicity that occurred during 1963–1964, about 25.2 years prior to its occurrence. The pattern of anomalous seismicity in the form of earthquake swarms preceding major earthquakes in the northeast India region can be regarded as one of the potential seismic precursors. Database constraints have been the main barrier to searching for this precursor preceding smaller earthquakes, which otherwise might have provided additional information on its existence. The entire exercise indicates that anomalous seismicity preceding major shocks is a common seismic pattern for the northeast India region, and can be employed for long-range earthquake prediction when better quality seismological data sets covering a wide range of magnitudes are available. Anomalous seismic activity is distinguished by a much higher annual frequency of earthquake occurrence than in the preceding normal and the following gap episodes. 相似文献
16.
To take the seismic zone that includes the great shock with M
s≥8.2 as the statistical unit of estimating b value can often lead to more large variance, because the seismogenic zone of the great shock with M
s≥8.2 are larger than that delineated in general seismic zone. Two-level statistical units are considered in this paper. The
seismic province is the first level unit that is suitable for group of earthquakes including the great shock of M
s≥8.5. A seismic province can be divided into several seismic zones. They can be taken as the second level unit for group of
quakes in which the super magnitude of the greatest shock do not exceed 8. Because of the nonstationarity in time of seismic
activity, the unbalancedness of data and differential of seismic temporal series feature in different areas need to be considered
when we select the time period for estimating b value. According to local conditions, the time period is selected at one’s discretion in order to reflect seismicity level
of this statistical unit in future 100 years.
Contribution No. 98A02039, Institute of Geophysics, China Seismological Bureau, China. 相似文献
17.
We investigated the seismicity in the aftershock area of a great earthquake occurring on April 20, 2006 (21:04 LT) in the
area of the Koryak Autonomous Okrug. This analysis of the aftershock process was based on a complete catalog of the earthquakes
that were recorded during April–May 2006 by the regional network of seismic stations operated by the Kamchatka Branch of the
Geophysical Service of the Russian Academy of Sciences. We also made use of a catalog of low magnitude events for May 2–17
as recorded by a mobile seismic network deployed in the rupture zone. We provide a review of seismicity for the Koryak Upland
for the period of instrumental observations in the 20th and early 21st centuries. 相似文献
18.
U. Yalçın Kalyoncuoglu 《Journal of Seismology》2007,11(2):131-148
In this study, the spatial distributions of seismicity and seismic hazard were assessed for Turkey and its surrounding area.
For this purpose, earthquakes that occurred between 1964 and 2004 with magnitudes of M ≥ 4 were used in the region (30–42°N and 20–45°E). For the estimation of seismicity parameters and its mapping, Turkey and
surrounding area are divided into 1,275 circular subregions. The b-value from the Gutenberg–Richter frequency–magnitude distributions is calculated by the classic way and the new alternative
method both using the least-squares approach. The a-value in the Gutenberg–Richter frequency–magnitude distributions is taken as a constant value in the new alternative method.
The b-values calculated by the new method were mapped. These results obtained from both methods are compared. The b-value shows different distributions along Turkey for both techniques. The b-values map prepared with new technique presents a better consistency with regional tectonics, earthquake activities, and
epicenter distributions. Finally, the return period and occurrence hazard probability of M ≥ 6.5 earthquakes in 75 years were calculated by using the Poisson model for both techniques. The return period and occurrence
hazard probability maps determined from both techniques showed a better consistency with each other. Moreover, maps of the
occurrence hazard probability and return period showed better consistency with the b-parameter seismicity maps calculated from the new method. The occurrence hazard probability and return period of M ≥ 6.5 earthquakes were calculated as 90–99% and 5–10 years, respectively, from the Poisson model in the western part of the
studying region. 相似文献
19.
Results are reported from a detailed study of central Kamchatka seismicity for the period 1962–1997 based on a modification
of the traditional approach. The approach involves (a) a detailed structure of the seismic region that recognizes the Kronotskii
and Shipunskii geoblocks and two further blocks, the continental slope, and the offshore portion, (b) a study of variations
in the rate of M = 3.0–7.2 earthquakes and the amount of seismic energy released at depths of 0–50 and 51–100 km, (c) a study
of seismicity variability, and (d) separate estimates of the recurrence of crust-mantle earthquakes (depths 0–50 km) and mantle
events (51–100 km). As a result, apart from corroborating the fact of a quiescence preceding the December 5, 1997 Kronotskii
earthquake (M 7.9), we also found that a relationship exists between its beginning and the position of the earthquake-generating
region relative to the mainshock epicenter. The quiescence dominates the seismic process during the pre-mainshock period and
is characterized by a decreased rate of earthquakes (the first feature) and a decreased amount of seismic energy release (the
second feature). Based on the first feature, we found that the quiescence started in 1987 throughout the entire depth range
(0–100 km) in both parts of the Kronotskii geoblock close to the rupture zone of the eponymous earthquake. As to the Shipunskii
geoblock, which is farther from the rupture zone, the quiescence began in the mantle of the inner area first (1988) and somewhat
later at depths of 0–50 km within the continental slope (1989). By the second feature, the quiescence began at shallower depths
in the inner area of the Kronotskii geoblock at the same time and later on (a year later) in the mantle (1988). Under the
continental slope of the trench in the Shipunskii geoblock the shallower quiescence also began in 1987, while it was 3 years
late in the inner zone (1990) and involved the earthquake-generating earth volume at depths of 0–100 km. These data are identical
with or sufficiently close to the estimate for the beginning of this quiescence using a circular area of radius 150 km that
combines the Kronotskii and Shipunskii geoblocks by the RTL method (1990). 相似文献
20.
2001年昆仑山口8.1级巨震后中国大陆、云南地震趋势研究 总被引:2,自引:1,他引:2
分析研究了2001年11月14日昆仑山口8.1级巨震对中国大陆云南未来几年地震趋势的影响,指出巨震后6年大陆可能仍然处于地震活跃期,其间大陆西部发生7.0级以上大震可能性较大;受2000-2001年欧亚带东南段大震活动过程及巨震调整影响,未来1-3年云南省可能进入新的活跃期,6.5级以上强震危险性增加。 相似文献