No abstract

Accurately and quickly identifying the types of natural and unnatural earthquake events is the basic premise of monitoring, prediction, early warning, and other study in the field of seismology, which is of great significance to the prevention, evaluation, emergency rescue, and other work of earthquake disasters. Convolutional neural network model is a representative artificial intelligence deep learning algorithm, which has been widely used in computer vision, natural language processing, object type identification, and other fields in recent years. In this study, AlexNet convolutional neural network model is selected to study the type identification of 1539 earthquake event waveform records in and around Ningxia Hui Autonomous Region, China. Earthquake event waveform records contain three types: natural earthquake, explosion, and collapse, in which both explosion and collapse are unnatural earthquakes. MATLAB software is used to build the training module and test module for AlexNet convolutional neural network model, and the earthquake event waveform record is transformed into an image format file of 224 times 224 pixels as input parameters. Finally, AlexNet convolutional neural network model has the ability of automatic identification of earthquake event types. The results of this study show that the identification accuracy of earthquake event type in training module is 99.97%, the average value of loss function is 0.001, the identification accuracy of earthquake event type in test set is 98.51%, and the average value of loss function is 0.059. After training and testing, 60 different types of earthquake event waveform records were randomly selected, and AlexNet convolutional neural network model was used to identify them automatically. The automatic identification accuracy of natural earthquakes, explosions, and collapses was 90%, 80%, and 85%, respectively. After training AlexNet convolutional neural network model with earthquake event waveform records, it can have accurate and fast automatic identification ability. The accuracy of automatic identification is comparable to that of professional seismic workers, and the time of automatic identification is greatly reduced compared with that of professional seismic workers. This study can provide an implementation idea of deep learning based on artificial intelligence for the identification of earthquake event types and make contributions to the cause of earthquake prevention and disaster reduction.

This paper presents a numerical analysis of two types of representative site profiles in the Yinchuan Plain under earthquake loading. The analyzed soil profiles, based on borehole investigations performed over the years, are used to explore the seismic response of the sites in this area. In total, eleven stratified soil models are used in this study, which can be grouped into two categories: a single interbedded soil model and multiple interbedded soil model. A one-dimensional equivalent linearization method is applied to evaluate the seismic response of different soil models under four exceeding probabilities in terms of peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), and spectral acceleration (Sa). The results show that the significant amplification effect of PGA occurs in rare and extremely rare earthquakes, with an amplification ratio of 1.4∼1.7 when the single silty clay layer is located at the model ground. In this scenario, the spectral acceleration is amplified at a period of approximately 1.0 s. For the multilayered soil cases, the amplification effect tends to decrease, whereas the characteristic periods increase with increasing numbers of soil layers and the ground acceleration is deamplified under a high motion intensity when the number of soil layers is ≥ 5. This study, to a certain degree, has reference value for seismic microzonation in this area.

By using shallow seismic exploration, composite drilling section exploration and sample dating test, we have obtained precise positions, burial depths of uppermost point and activity characteristics of Hetan-Guotan buried fault and Zhenjing-Zhenbei buried fault in Zhongwei Basin. The results show that the latest active period of Hetan-Guotan buried fault is the middle-late Middle Pleistocene, and the latest active period of Zhenjing-Zhenbei buried fault is the Early and Middle Pleistocene. The two buried faults became inactive at the end of the Middle Pleistocene and have been inactive since the Late Pleistocene.

Remote-sensing images are visually interpreted in this study to obtain information on buildings in the urban and rural areas of Ningxia, China. Overall, area estimates yielded by the proposed equations followed a normal distribution. Correlation and error analyses indicated that the coefficients are reasonable and reliable and that the building area estimates have an accuracy of 90% and are also reliable. These results were used in conjunction with drone aerial images, Baidu street view images, and paper maps to determine the seismic performance (SP) of the buildings in the study area. On this basis, the buildings were classified into three groups, namely, those with the required SP, suspected substandard SP, and substandard SP. Examination based on the field survey data collected from at least one sample site in each village and township in all 22 county-level divisions (CLDs) of Ningxia showed an average SP accuracy of 76% for all 22 CLDs and an SP accuracy exceeding 70% for 20 (91%) of the 22 CLDs. Based on this approach and the results obtained, the ArcGIS spatial analysis method was employed to determine the percentages and distribution patterns of the buildings in the three SP groups in the 22 CLDs. The results revealed the following features. Buildings with the required SP were clustered in the urban areas of each CLD, with a few in the village and township government seats. Buildings with suspected substandard SP were distributed predominantly in the rural-urban fringe (RUF) areas and the village and township government seats. Buildings with substandard SP were found primarily in urban villages, RUF areas, and urban areas. The soundness of the spatial analysis results was corroborated by the field survey data, lending credence to the feasibility of the proposed calculation method. This method can satisfy the real-world need for rapidly assessing the SP and distribution of buildings in a region before an earthquake occurs and provide a reliable reference for disaster prevention, mitigation, and relief efforts.