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951.
Zhengxiang Fu 《地震科学(英文版)》1992,5(2):225-235
The Kaoiki, Hawaii, earthquake with magnitude 6. 6 of November 16, 1983 was a strike-slip faulting event on a fault with large dip angle. The results for mechanisms of smaller events before and after the Kaoiki mainshock show that there were two kinds of mechanisms: (1) strike-slip on the fault with large dip angle; (2) slip on the crustal discontinuity plane with smaller dip angle, and systematic and alternative changes in the mechanisms were observed. 相似文献
952.
对印尼地区3574次M≥5.0地震震源断层面上的海潮负荷应力进行计算,研究了地震断层上的负荷应力随深度变化以及随断层倾角和走向的变化特征.结果表明,地震断层上的负荷正应力大于负荷切应力.逆断层上的负荷应力最大,其它依次为斜滑断层、正断层和走滑断层.倾角范围在0°—50°的断层上的负荷正应力随倾角增大有减小趋势,负荷切应力在30°—50°倾角范围的断层上较大.负荷应力随断层走向的趋势性变化不明显.不同类型断层上的负荷正应力和切应力在震源深度15km处均达到最大,之后随深度增加而减小.当震源深度小于40km时,断层面上的海潮负荷应力的量级与固体潮应力相当.因此指出,在潮汐应力对地震影响的研究中,对震源深度小于40km的海洋和沿海地震,除固体潮汐应力外还需要考虑海潮负荷应力的影响. 相似文献
953.
954.
Earth medium is not completely elastic, with its viscosity resulting in attenuation and dispersion of seismic waves. Most viscoelastic numerical simulations are based on the finite-difference and finite-element methods. Targeted at viscoelastic numerical modeling for multilayered media, the constant-Q acoustic wave equation is transformed into the corresponding wave integral representation with its Green’s function accounting for viscoelastic coefficients. An efficient alternative for full-waveform solution to the integral equation is proposed in this article by extending conventional frequency-domain boundary element methods to viscoelastic media. The viscoelastic boundary element method enjoys a distinct characteristic of the explicit use of boundary continuity conditions of displacement and traction, leading to a semi-analytical solution with sufficient accuracy for simulating the viscoelastic effect across irregular interfaces. Numerical experiments to study the viscoelastic absorption of different Q values demonstrate the accuracy and applicability of the method. 相似文献
955.
In the present paper, the boundary element method with exterior collocation was applied to two-dimensional elastodynamic problems. The stability of the numerical solution was discussed and the collocation rule of source points outside the region being studied was investigated in the frequency domain by means of the computed error in the boundary displacement and the condition number of the coefficient matrix for two typical wave propagation problems. The achieved results are helpful to the practical application of this method to earthquake ground motion analysis. 相似文献
956.
957.
958.
川滇地区7级大震前中强震震源机制变化 总被引:7,自引:0,他引:7
分析了 70年代以来 ,川滇地区发生的 8次 7级大震前 5年内 ,发生在大震孕震区和震源区内的中强震震源机制解时空分布。结果表明 ,最早中强震发生在大震震源区或其附近 ,其发震应力场与区域构造应力场一致 ,与大多数大震发震应力场一致或接近。大多数中强震震源破裂特征与大震明显不同。之后有多次中强震发生在距大震震源区较远的大震孕震区内其他地方 ,它们的发震应力场往往经历了与区域构造应力场和大震应力场一致与不一致的多次交替变化。大震前最后 1个中强震也发生在距大震震源区较近的地方 ,其发震应力场与大震发震应力场明显不一致 ,偏转了 30°~ 5 0° ,或更多 ,大多数也与区域构造应力场不一致 ,有的中强震发震断裂破裂特征与大震不一致。大震前中强震震源机制的变化 ,反映了大震孕育过程的不同阶段 ,区域构造应力场的时空调整变化和增强过程 ,以及由此引发的构造断裂异常活动 ,揭示出与大震发生有关的应力场和震源破裂特征信息 相似文献
959.
By the measurement of the wind directional indicator of the Cretaceous desert in Ordos Basin, the regularity of the paleoprevailing
wind directions and pattern of the paleowind belts are revealed. It is considered that the desert was controlled by a planetary
wind system. In the early stage, the subtropical high pressure zone drifted south and northwards with short cycles, resulting
in the alternation of westerlies and northeast trades; in the late stage, the subtropical high pressure zone drifted southwards
with a long cycle, placing the desert under the westerly belt and making the desert completely controlled by the westerly
belt. The reconstruction of the paleowind belts has provided the evidence of the general circulation of the atmosphere for
the pattern of the circulation before the uplift of the Tibetan Plateau 相似文献
960.
Weiwei Fu 《Ocean Dynamics》2018,68(10):1311-1319
Ocean heat content (OHC) plays an important role in ocean carbon uptake (OCU). However, the changes of OHC and OCU are model-dependent and have large bias compared with observations. This makes it difficult to quantify their relationship. Here, we propose a new metric to measure the uncertainty of the relationship between OHC and OCU. The new metric can link the uncertainty with different OCU processes and allow direct comparison of the impact of OHC on the OCU in different simulations. The metric is illustrated in different simulations of the Coupled Model Intercomparison Project phase 5 (CMIP5) in which atmospheric CO2 is increased by 1%/year. Results show that OHC in 0–500 m plays a dominant role in the OCU for the radiatively coupled (RAD) experiment because warming intensifies the carbon loss in the upper ocean. Relatively, OHC in the intermediate waters (500–2000 m) are crucial for the fully coupled and biogeochemically coupled experiment because this layer largely regulates the OCU. For different ocean basins, the intermediate Southern Ocean and deep North Atlantic are more important for the OCU in the RAD simulation. The metric also suggests the importance of global overturning circulation and the Southern Ocean in the OCU. 相似文献