Spatiotemporal coda Q variations in the northeastern margin of the Qinghai–Tibet Plateau, China

IF 1.3 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Journal of Earth System Science Pub Date : 2024-06-04 DOI:10.1007/s12040-024-02316-0

Zhaocheng Liang, Xiao Guo, Rui Zou, Xuzhou Liu, Manzhong Qin, Shaohua Li

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Abstract

The seismic quality factor (Q) is an important physical parameter to characterize seismic wave attenuation. Therefore, analyzing its spatiotemporal variation is essential to better understand tectonic activity, characterize earthquake source mechanisms, and assess seismic hazards. In this study, we used a single-scattering model to calculate Q for coda waves (Q_c values) generated by earthquakes with epicentral distances <100 km and magnitudes M > 2.0 recorded in 2000–2023 in the northeastern margin of the Qinghai–Tibet Plateau (the study area). The calculated dependence of Q_c on the bandpass filter central frequency f in the study area was \({Q}_{c}=\left(72.40\pm 9\right){f}^{\left(1.10\pm 0.06\right)}\), \({Q}_{c}=\left(100.95\pm 15\right){f}^{\left(1.03\pm 0.07\right)}\), and \({Q}_{c}=\left(128.76\pm 20\right){f}^{\left(0.97\pm 0.07\right)}\) within lapse-time windows of length 20, 30, and 40 s, respectively. To estimate Q_c in distinct active tectonic and fault regions, we divided the study area into two subregions, the Haiyuan and Qinling active tectonic zones. We determined a strong spatial correlation between the Q_c distribution and tectonic activity in the study area, with correspondingly low Q_c values. Finally, by analyzing the temporal evolution of Q_c, we established that nearly all strong earthquakes (M > 6.0) that occurred in the study area in 2000–2023 were preceded by a 10–27% decrease in Q_c values, a phenomenon possibly related to the ‘rock dilatancy’ theory.

Research highlights

1.
Characteristics of code-wave attenuation in the northeastern margin of the Qinghai–Tibet Plateau.
2.
Strong correlation between Q_c values and active blocks distribution in the northeastern margin of the Qinghai–Tibet Plateau.
3.
Most strong earthquakes in the northeastern margin of the Qinghai–Tibet Plateau were preceded by a decrease in Q_c values.

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中国青藏高原东北缘的时空尾波 Q 值变化

摘要地震品质因数（Q）是表征地震波衰减的重要物理参数。因此，分析其时空变化对于更好地理解构造活动、确定震源机制和评估地震灾害至关重要。在本研究中，我们使用单散射模型计算了 2000-2023 年青藏高原东北缘（研究区）震中距 100 km、震级 Mgt; 2.0 的地震产生的残波 Q 值（Qc 值）。在研究区，Qc与带通滤波器中心频率f的计算关系为\({Q}_{c}=\left(72.40\pm 9\right){f}^{left(1.10\pm 0.06\right)}),\({Q}_{c}=\left(100.和（{Q}_{c}=\left(128.76\pm 20\right){f}^{\left(0.97\pm 0.07\right)}\) 分别在长度为 20、30 和 40 秒的时间窗口内。为了估算不同活动构造和断层区域的Qc，我们将研究区域划分为两个子区域，即海原活动构造带和秦岭活动构造带。我们确定研究区的 Qc 分布与构造活动之间存在较强的空间相关性，Qc 值也相应较低。最后，通过分析 Qc 的时间演变，我们确定了 2000-2023 年在研究区发生的几乎所有强震（M > 6.0）之前，Qc 值都下降了 10-27%，这一现象可能与 "岩石膨胀 "理论有关。青藏高原东北缘码波衰减特征2.青藏高原东北缘Qc值与活动块体分布密切相关3.青藏高原东北缘大部分强震发生前Qc值均有下降。

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来源期刊

Journal of Earth System Science Earth and Planetary Sciences-General Earth and Planetary Sciences

CiteScore

3.20

自引率

5.30%

发文量

226

期刊介绍： The Journal of Earth System Science, an International Journal, was earlier a part of the Proceedings of the Indian Academy of Sciences – Section A begun in 1934, and later split in 1978 into theme journals. This journal was published as Proceedings – Earth and Planetary Sciences since 1978, and in 2005 was renamed ‘Journal of Earth System Science’. The journal is highly inter-disciplinary and publishes scholarly research – new data, ideas, and conceptual advances – in Earth System Science. The focus is on the evolution of the Earth as a system: manuscripts describing changes of anthropogenic origin in a limited region are not considered unless they go beyond describing the changes to include an analysis of earth-system processes. The journal''s scope includes the solid earth (geosphere), the atmosphere, the hydrosphere (including cryosphere), and the biosphere; it also addresses related aspects of planetary and space sciences. Contributions pertaining to the Indian sub- continent and the surrounding Indian-Ocean region are particularly welcome. Given that a large number of manuscripts report either observations or model results for a limited domain, manuscripts intended for publication in JESS are expected to fulfill at least one of the following three criteria. The data should be of relevance and should be of statistically significant size and from a region from where such data are sparse. If the data are from a well-sampled region, the data size should be considerable and advance our knowledge of the region. A model study is carried out to explain observations reported either in the same manuscript or in the literature. The analysis, whether of data or with models, is novel and the inferences advance the current knowledge.