刘奕君,李小军,赵晓芬,徐超,温增平. 2024. 2014年云南鲁甸MW6.1地震强地面运动模拟. 地震学报,46(4):677−694. DOI: 10.11939/jass.20220216
引用本文: 刘奕君,李小军,赵晓芬,徐超,温增平. 2024. 2014年云南鲁甸MW6.1地震强地面运动模拟. 地震学报,46(4):677−694. DOI: 10.11939/jass.20220216
Liu Y J,Li X J,Zhao X F,Xu C,Wen Z P. 2024. Strong ground motion simulation for the 2014 MW6.1 Ludian,Yunnan earthquake. Acta Seismologica Sinica46(4):677−694. DOI: 10.11939/jass.20220216
Citation: Liu Y J,Li X J,Zhao X F,Xu C,Wen Z P. 2024. Strong ground motion simulation for the 2014 MW6.1 Ludian,Yunnan earthquake. Acta Seismologica Sinica46(4):677−694. DOI: 10.11939/jass.20220216

2014年云南鲁甸MW6.1地震强地面运动模拟

Strong ground motion simulation for the 2014 MW6.1 Ludian,Yunnan earthquake

  • 摘要: 基于震源运动学模型,采用宽频带混合模拟方法,对2014年鲁甸MW6.1地震开展了考虑复杂震源破裂过程的地震动模拟,将代表性场点的模拟结果与实际观测的强震记录进行对比,分析了不同震源模型对场点强地面运动特征影响的差异。结果表明:就震源尺度有限的中等地震而言,地震矩相近的不同震源破裂模型对震中距稍远场点的地震动影响差异相对较小,而对近震源区场点的地震动特征影响差异则较为明显。此外,不同震源模型模拟的地震动参数空间分布结果显示,不同震源模型对地震动的空间分布形态具有显著影响。

     

    Abstract:
    Based on the intensity and aftershock distribution, researchers unanimously agree that the rupture of the 2014 MW6.1 Ludian, Yunnan earthquake exhibits a certain degree of complexity. Zhang et al2015) used broadband strong motion records within a 250 km range from the epicenter, along with full waveform data of near-field and far-field broadband body wave data, to invert the rupture process of the Ludian MW6.1 earthquake base on both a single fault model and two intersecting conjugate fault models. Their results indicate that the Ludian MW6.1 earthquake was a complex seismic event, characterized by the successive rupture of two conjugate faults in the northwest and northeast directions. Significant progress has been made in studying the characteristics of strong ground motion related to the Ludian earthquake and associated issues. The existing conclusions about the distribution of seismic parameters in affected region are directly inferred or indirectly synthesized from existing data, yet the seismic characteristics caused by complex seismic source ruptures have not been considered.
    To investigate the influence of different rupture process models on ground motion simulation of the MW6.1 Ludian earthquake, a hybrid broadband ground motion simulation method known as the GP method (Graves, Pitraka, 2010) was applied to synthesize acceleration, velocity waveforms, and acceleration response spectra in the near-field area based on kinematic source models. The source models used for comparison in this study are derived from Zhang et al2015), which includes two single fault rupture models and one intersecting conjugate fault model. The study adopted the crustal velocity structure model of the Yunnan region to calculate the Green’s function.
    The GP method combines a deterministic approach in the low-frequency range ( f<1 Hz) with a semi-stochastic approach in the high-frequency range ( f >1 Hz). For f<1 Hz, this methodology allows for a theoretically rigorous representation of fault rupture and wave propagation effects, to generate ground motion waveforms and amplitudes. In contrast, high-frequency ( f >1 Hz) ground motions are modeled through random source radiation, simplified theoretical wave propagation, and scattering effects.Simulation results for representative sites were compared with observed strong motion recordings, and the impacts of three different source rupture models on strong ground motions were analyzed. The results demonstrate that for moderate earthquakes with limited fault dimensions, differences in strong ground motion characoncernedcteristics among different source rupture models with similar seismic moments are not pronounced in far fields but are distinct in near-fields. Additionally, the distributions of intensity measurements of ground motions are provided, and it is found that the simulation results based on the conjugate fault model are more consistent with the field-surveyed macroseismic intensity of MW6.1 Ludian earthquake, Yunnan in 2014. This indicates that the source rupture model plays a crucial role in the spatial distribution pattern of strong ground motions and their characteristics. Therefore, elaborate source rupture models are of great value for reasonably estimating the peak ground acceleration, peak ground velocity, frequency spectrum, duration, and time history of seismic motion in the near-source area, as well as assessing seismic hazard in area.
    This article reveals the influence of complex focal rupture processes on the characteristics and spatial distribution of strong ground motion.

     

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