Spatial Heterogeneity of b Values in Northeastern Tibetan Plateau and Its Interpretation

Author:

Hu Nan123,Han Peng4ORCID,Wang Rui4ORCID,Shi Fuqiang2,Chen Lichun5,Li Hongyi13

Affiliation:

1. Key Laboratory of Intraplate Volcanoes and Earthquakes, Ministry of Education, China University of Geosciences (Beijing), Beijing 100083, China

2. Shaanxi Earthquake Agency, Xi’an 710068, China

3. School of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing 100083, China

4. Department of Earth and Space Science, Southern University of Science and Technology, Shenzhen 518055, China

5. College of Earth Sciences, Guilin University of Technology, Guilin 541004, China

Abstract

The northeastern margin of the Tibetan Plateau (NE Tibetan Plateau) exhibits active geological structures and has experienced multiple strong earthquakes, with M ≥ 7, throughout history. Particularly noteworthy is the 1920 M81/2 earthquake in the Haiyuan region that occurred a century ago and is documented as one of the deadliest earthquakes. Consequently, analyzing seismic risks in the northeastern margin of the Tibetan Plateau holds significant importance. The b value, a crucial parameter for seismic activity, plays a pivotal role in seismic hazard analyses. This study calculates the spatial b values in this region based on earthquake catalogs since 1970. The study area encompasses several major active faults, and due to variations in b values across different fault types, traditional grid-search methods may introduce significant errors in calculating the spatial b value within complex fault systems. To address this, we employed the hierarchical space–time point–process (HIST-PPM) method proposed by Ogata. This method avoids partitioning earthquake samples, optimizes parameters using Akaike’s Bayesian Information Criterion (ABIC) with entropy maximization, and theoretically allows for a higher spatial resolution and more accurate b value calculations. The results indicate a high spatial heterogeneity in b values within the study area. The northwestern and southeastern regions exhibit higher b values. Along the Haiyuan fault zone, the central rupture zone of the Haiyuan earthquake has relatively higher b values than other regions of this fault zone, which is possibly related to the sufficient release of stress during the main rupture of the Haiyuan earthquake. The b values vary from high in the west to low in the east along the Zhongwei fault. On the West Qinling fault zone, the epicenter of the recent Minxian–Zhangxian earthquake is associated with a low b value. In general, regions with low b values correspond well to areas with moderate–strong seismic events in the past 50 years. The spatial differences in b values may reflect variances in seismic hazards among fault zones and regions within the same fault zone.

Funder

National Key Research and Development Program of China

Natural Science Basic Research Program of Shaanxi

Active Faults Exploration and Seismic Hazard Assessment in Fengxi, Xi’an, China

Publisher

MDPI AG

Reference119 articles.

1. Frequency of earthquakes in California;Gutenberg;Bull. Seismol. Soc. Am.,1944

2. A method for determining the value of b in a formula logn = a − bM showing the magnitude frequency relation for earthquakes;Utsu;Geophys. Bull. Hokkaido Univ.,1965

3. The frequency-magnitude relation of microfracturing in rock and its relation to earthquakes;Scholz;Bull. Seismol. Soc. Am.,1968

4. On the stress dependence of the earthquake b value;Scholz;Geophys. Res. Lett.,2015

5. Relationship between earthquake b-values and crustal stresses in a young orogenic belt;Wu;Geophys. Res. Lett.,2018

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