排序方式： 共有16条查询结果，搜索用时 171 毫秒
1.
为了配合汶川地震科学深钻,弄清楚钻孔附近浅层的断层面结构,中国地震局地球物理研究所分别在四川省绵竹市天池乡和四川省绵阳市南坝镇布设15套南非矿山地震研究所(IMS)生产的矿山地震仪.分析矿山地震仪天然微震监测中仪器布设、数据采集和数据处理等方面遇到的问题,介绍与该仪器对应的数据的文件格式,并实现该数据与通用地震数据格式SAC二进制格式的转换. 相似文献
2.
3.
For microearthquake surveys conducted with small networks in regions where the seismic velocity structure has large vertical gradients, the formal errors accompanying hypocentral solutions obtained by a generalized inverse method may be misleading since they do not incorporate the effects of nonlinearity in travel times. An alternative method for estimating uncertainties involves calculating travel time residuals over a regular grid and using the F statistic to contour confidence volumes. We present a statistical expression for the latter confidence limits that is applicable when an independent estimate of arrival time errors is available from observations accumulated for a number of earthquakes. Synthetic experiments comparing the results of the grid search and generalized inverse methods show that in cases where solutions are obtained either without S wave information or for epicenters which lie well outside the network, the effects of nonlinearity on the shape of the confidence regions may be significant. However, for the well-observed events both methods yield comparable confidence volumes in good agreement with the distribution of hypocenters obtained from repeated locations incorporating random errors. The generalized inverse method has the advantage that it requires fewer calculations, so the examination of systematic errors in hypocentral parameters produced by uncertainties in the seismic velocity structure can be studied in a more computationally efficient manner. Except in the cases of poorly resolved earthquakes, the effects of nonlinearity on uncertainties in hypocentral parameters can be observed by the application of the F statistic to the variation of the generalized inverse travel time residuals with focal depth. 相似文献
4.
基于山西数字地震台网2001—2010年记录的地震,研究临汾地区的地震活动,并寻找重复微震,进而计算深部滑动速率。双差法重新定位后的地震图像显示,在研究时段内,临汾地区29.3%以上的地震发生在临汾盆地平原腹地的苏堡断裂两侧,即沿NNE向分布南、中、北3个隆起间的2个次级凹陷之一的临汾-洪洞次级凹陷内;震源深度分布与研究区的深部构造较为相符。通过波形互相关分析,识别出波形高度相似的49组相似地震对和25组多重相似对。大部分相似地震活动表现为非周期性,复发间隔从数分钟到数百天不等。依据在同一地震台站记录的波形塑造参考地震的波形,用以量取每个地震相对于参考地震的S—P相对到时差,并确定每个地震与多重相似对质心的相对距离,从而挑选出每组地震中的重复事件。识别出研究区2组重复地震,并由此估算得到滑动速率为1.9~2.8mm/a,该值与同时段GPS和地质等浅表观测的滑动速率值基本相符。 相似文献
5.
6.
7.
Yunlong Liu Cai Liu Lei Qiu Vera Schlindwein Haijiang Zhang 《Marine Georesources & Geotechnology》2013,31(2):201-211
ABSTRACTIn this paper, we describe the results of a first pilot experiment of passive seismic monitoring near the active Longqi hydrothermal vent at the Southwest Indian Ridge during Chinese cruise DY115-30. During 102-day experiment, we recorded over 2,000 seismic events on a single ocean bottom seismometer with hydrophone close to the hydrothermal field. We classified these events into the following three classes based on their time–frequency characteristics: (1) volcano tectonic microearthquakes (VTMs); (2) regional earthquakes; (3) short-duration events (SDEs). We preliminarily located the 1,277 VTMs using a single-station location method. Our results revealed hypocenters primarily beneath the axial valley ridge which is about 10?km away from hydrothermal vent and extending to the upper mantle at a depth of 15?km. Two discrete swarms of VTMs occurred during our survey period. The SDEs show a complex frequency characteristics ascribed to clusters of monochromatic waves around different frequencies. This suggests that SDEs result from combination of harmonic waves resonating in fluid-filled pipes and cracks. 相似文献
8.
Microearthquake activity in the Dead Sea region 总被引：2，自引：0，他引：2
9.
Interpretation ofP/S-wave successions is used in induced or passive microseismicity. It makes the location of microseismic events possible when the triangulation technique cannot be used. To improve the reliability of the method, we propose a technique that identifies theP/S-wave successions among recorded wave successions. A polarization software is used to verify the orthogonality between theP andS polarization axes. The polarization parameters are computed all along the 3-component acoustic signal. Then the algorithm detects time windows within which the signal polarization axis is perpendicular to the polarization axis of the wave in the reference time window (representative of theP wave). The technique is demonstrated for a synthetic event, and three application cases are presented. The first one corresponds to a calibration shot within which the arrivals of perpendicularly polarized waves are correctly detected in spite of their moderate amplitude. The second example presents a microseismic event recorded during gas withdrawal from an underground gas storage reservoir. The last example is chosen as a counter-example, concerning a microseismic event recorded during a hydraulic fracturing job. The detection algorithm reveals that, in this case, the wave succession does not correspond to aP/S one. This implies that such an event must not be located by the method based on the interpretation of aP/S-wave succession as no such a succession is confirmed. 相似文献
10.
南冲绳海槽海域微震活动的初步探讨 总被引：1，自引：0，他引：1
通过解析在南冲绳海槽海域投放的海底地震仪（ＯＢＳ）记录到的天然地震资料，得到近垂直海槽走向的微震震中分布．根据震中分布与海底地形、地质构造的对比，提出：南冲绳海槽海域的微震活动频繁且多数集中于海槽轴部的地堑和琉球岛弧中部． 相似文献