This article analyzes and explores the curve anomalies caused by the influence of meteorological factors on the cave strain of four stations in eastern Hubei region, in order to identify the influence characteristics and provide more powerful technical support for earthquake prediction.

The cave strainmeter in Wuhan area is easy to be disturbed by air pressure, and the observation curve shows V-type and high-frequency jump. There is a linear correlation between the deformation of cave strainmeter and air pressure variation. Using MATLAB software, wavelet decomposition and STFT are used to analyze the time-frequency response characteristics of cave strainmeter disturbed by air pressure in Wuhan area. The results show that the NS component of cave strainmeter has the greatest influence in the frequency-band of 0.02-0.2 Hz, while the EW component is mainly affected in the frequency-band of 0.02-0.15 Hz.

Comparative analysis of the observation data of VS vertical pendulum and DSQ water pipe inclinometer from 2015 to 2022 at Macheng station is conducted. The results show that: 1) The tidal observation data is continuous and reliable, the instrument works normally and stably, and the quality of data and the accuracy of tidal factor are at the leading level in China. 2) The data of VS vertical pendulum is more stable and has a low failure rate. 3) In terms of coseismic response, the sensitivity of DSQ water pipe inclinometer is higher than that of VS vertical pendulums, and the DSQ water pipe inclinometer can clearly record seismic events over M5.5 and epicentral distance within 1 500 km.

We analyze the atmospheric pressure effect of underground water at Jingzhou seismic station using the linear regression method, calculate the atmospheric pressure coefficient of water level and water temperature, and correct the data. The spectrum analysis results show that the linear regression method can effectively remove the atmospheric pressure effect, and is of great significance for the interference analysis of fluid data and the extraction of real earthquake precursor anomalies.

By analyzing two sets of water temperature equipment in Jingmen well, this paper checks the observation quality of the water temperature of Jingmen well, summarizes the dynamic change characteristics of the water temperature of Jingmen well and various interference factors encountered in daily observation, so as to provide reference for future water temperature observation when such anomalies occur again. The integrity rate of well water temperature data is calculated and the main factors affecting the integrity rate are analyzed. It is considered that the water temperature instrument in Jingmen well has high reliability and can provide reliable data for earthquake monitoring and prediction.

The YRY-4 borehole strainmeter at Xiangyang station has been operating steadily from 2007 to July 2020. Since July 2020, due to the small change in compressive strain, the NE component has not changed significantly compared to other components. In daily business processing, it is believed that the data is distorted and the NE component is damaged. This article analyzes the data of each component of the YRY-4 borehole strainmeter at Xiangyang station and concludes that the NE eastern component is not damaged, but there is still a trend of solid tide and annual variation. At the same time, the correlation of surface strain is calculated, and data quality influencing factors and seismic reflection ability analysis are conducted. It can be concluded that the strain components of YRY-4 borehole at Xiangyang station basically meet self inspection and can continue to be observed. The NE component is not damaged.

Seismic wave is a typical stress wave propagating stress disturbance, which produces both motion and deformation effects at the same time. In this paper, the seismometer which reflects the motion effect of seismic wave and the borehole strainmeter which reflects the deformation effect are compared, so as to provide reference for obtaining more accurate seismic analysis and prediction data.

Through the analysis of the trend changes of 28 measurement items of 11 sets of tiltmeters at 6 stations within 100 km near the Lintan-Tanchang fault zone, it can be found that in the first three years after earthquake, the trend changes of most of the observation data showed different degrees of anomalies. Especially during the period of 2008-2022, the Tanchang DSQ-EW component showed an eastward-dipping trend at a certain rate(the annual trend is obvious), and there were two obvious abnormal changes in the trend during this period(from the east-dipping trend changed to a west-dipping trend), about half a year(7 months and 5 months) after these two turning points, moderately strong earthquakes occurred near the Lintan-Tanchang fault(Minxian-Zhangxian M_S6.6 earthquake and Xiahe M_S5.7 earthquake), and after the earthquake, the observation data basically returned to the original trend.

The background noise level and power spectral density of the comparison base of Wuhan seismic station are calculated, and the root mean square (RMS) value of noise in the range of 1-20 Hz is given. According to the calculation results and in accordance with the Technical Requirements for the Observation Environment of Seismic Stations, the background noise of the comparison base of the Wuhan seismic station was rated, and the reasons for the change of the background noise of the comparison base of the Wuhan seismic station with time were analyzed, and optimization suggestions were put forward. The background noise level of the station comparison base is low, and the site environment is suitable for the instrument comparison measurement.

By analyzing the geomagnetic data noise and baseline value changes at Yingcheng station, various factors affecting data quality and deficiencies in station construction are explored. The results show that: 1) The interference of Wuhan subway operation is the primary factor affecting the geomagnetic background noise. 2) The noise of proton vector observation is mainly affected by the air temperature, the higher the temperature, the higher the noise. 3) The large annual temperature difference and high humidity in the recording room cause the baseline value to drift, and the observation data have many sudden jumps. 4) Instrument failure, greening operation and production activities may also reduce data quality.

The time-frequency analysis of geomagnetic observation data of Yingcheng seismic monitoring station since 2018 is carried out by using fast Fourier transform, and the frequency domain characteristics of geomagnetic data are obtained, which provides information for identifying interference factors in daily geomagnetic data processing, and has guiding significance for improving the quality of geomagnetic observation data.

The magnetometer at Zhongxiang station is mainly affected by the interference of observation system, construction and geophysical events, and often superimposes the next interference when the observation data form is not stable after the last interference event. In order to eliminate the influence of interference in time and improve the quality of observation data, starting from several typical events, the influence of data quality, instrument background noise, and the change of background noise with temperature are analyzed.

In order to understand the regional vibration amplitude of an industrial park, by analyzing the vibration source, the on-site test plan is formulated, the test data is analyzed, and the VC curve is used as an evaluation indicator to comprehensively evaluate the environmental vibration of the venue of the industrial park.

Eleven seismic data recorded by DZW gravimeter at Yichang center station from 2020 to 2022 were selected to analyze the co-seismic response characteristics.The results show that the delay time of DZW gravimeter coseismic response is directly proportional to the epicenter distance, and the response duration is positively correlated with the magnitude.For the earthquakes with similar epicentre distance and different magnitude, the maximum response amplitude and duration of DZW gravimeter are proportional to the magnitude.The maximum coseismic response amplitude of the DZW gravimeter is related to the magnitude and epicenter distance.

This paper introduces in detail the material selection of metal spring, the design spring parameter, requirements of heat treatment, turning spring treatment and other key technologies of DZW relative gravity instrument. The DZW relative gravimeters made of this batch springs can accurately measure the changes in solid tides, seismic information and some precursor information. The spring performance meets the design requirements of continuous gravimeter.

The WGM2012 gravity anomaly data is used to calculate the Moho depth in Papua New Guinea under the spherical coordinate system of the spatial domain. By separating the regional gravity field, the gravity anomaly caused by the fluctuation of Moho surface is obtained. The average deviation between the calculated results and the Moho depth results of the CRUST1.0 model is 0.44 km, and the standard deviation is 3.17 km. The results show that the depth distribution of Moho in Papua New Guinea has obvious regionalized structural features and is related to the subduction and collision of the area.

Natural earthquake is the most common source of seismology research. The research of underground medium wave velocity change using repeated earthquake data has some important results, but it is limited by time and space distribution and quantity, which is suitable for structural detection and measurement of wave velocity change to global scales. Background noise as another natural source, it has small time and space limitations, and its resolution and accuracy are higher than those of repeated earthquake. Artificial seismic source is not influenced by region and station density, its detection accuracy can reach to 10-4 level. Compared with repeated earthquake and background noise, artifical source can identify the seismic wave velocity change caused by tectonic stress. In recent years, the use of methods such as natural repeated earthquake, background noise, and artificial source to measure wave velocity change in underground medium has become a hot research topic in seismology. Through the accurately measuring of underground medium change, we can study the physical process and promote earthquake prediction. This paper introduces the principle, method and progress in the field of seismology of natural repeated earthquake, background noise and artificial seismic source. Finally, the advantages and limitations of several kinds of methods in practical application are presented.

We collect 189 high signal-to-noise ratio teleseismic waveform events with epicenter distance of 30°-90° and magnitude of 5.5 and above of Hubei digital seismic network recorded during 2016-2019 to extract the receiver functions(RFs) by the time domain deconvolution method, and obtain the high-resolution images of crustal thickness (H) and V_P/V_S (κ) by using the H-κ-c method with the harmonic corrections on Ps and its crustal multiples (PpPs, PsPs+PpSs) in P-wave receiver functions. The results show that the crustal thickness of Hubei region shows the structural feature of thick in the west and thin in the east. The thinnest crustal thickness in the Jianghan basin is only about 30 km.  The crustal thickness is slightly higher than 35 km, with a velocity ratio greater than 1.73 in the Dabie mountain area, which may be related to the two periods of strong sinistral translation of Tan-Lu fault zone during the late Triassic and late Jurassic, as well as the upwelling of mantle thermal material and magma intrusion into the crust in the southern section of Tan-Lu fault zone.

Using the HASH method to calculate the source mechanism solutions for earthquakes above ML2.5 in the Hetao seismic zone and above ML2.0 in the Hoho depression from 2008 to 2020, and retaining the source mechanism solutions with better data quality results. Using grid search method to invert the stress field directions of three tectonic zones in the Hetao seismic zone, namely Linhe depression, Baiyanhua depression, and Huhe depression. The results showed that: 1) The stress field directions in the Linhe depression and the Hetao seismic belt are relatively consistent, and the compressive stress axis is distributed in a northeast direction; 2) Both Baiyanhua and Huhe depressions exhibit clockwise twisting changes, and the compressive stress axis is distributed in a northeast direction. It is speculated that due to the clockwise movement of the Ordos block in the direction of the pointer, the northeast edge of the Hetao seismic belt is subjected to southeast stretching, resulting in a regional difference in the direction of the stress field between Baiyanhua and Huhe depressions.

Using 8 779 event waveforms recorded at 55 seismic stations of Hubei seismic network from 2013-01 to 2021-07 as the dataset, the optimal model of convolutional neural network(CNN) is trained for seismic detection, and the recurrent neural network(RNN) method is used for seismic phase arrival time picking. The advantages and shortcomings of the RNN model, AR-Pick, STA/LTA algorithms are compared and analyzed, and the relationship between the picking results of RNN model and the signal-to-noise ratio, epicentral distance and magnitude are further analyzed. The results show that the convolutional neural network trained with a small number of datasets can also have excellent classification performance, and the RNN model is with lower accuracy in P-wave and S-wave phase arrival time picking compared with AR-Pick, STA/LTA algorithms, and its seismic phase picking results are more strongly correlated with signal-to-noise ratio of waveforms, and have little relationship with epicentral distance and magnitude of earthquakes. Therefore, for regions with fewer earthquakes, the optimal CNN model can be trained for seismic detection using fewer seismic waveform data, and the P-wave phase arrival is picked up by AR-Pick algorithm, and the S-wave phase arrival is picked up by STA/LTA algorithm, which can improve the accuracy of seismic detection and phase picking.

Based on the 572 surface wave magnitudes measured by Danjiang seismic station in 2018, compared with the surface wave magnitudes of the seismic observation report of CENC, we analyze the relationship between the magnitude deviation and magnitude, epicentral distance, and epicenter azimuth. The results show that the MS magnitude of Danjiang seismic station is 0.13 lower than that of CENC, and the magnitude deviation decreases gradually with the increase of magnitude and epicentral distance. The magnitude deviation is not significantly affected by epicenter azimuth.

Based on the precursory observation data of geophysical field in the seismogenic zone and its adjacent area before and after the Jinggu M6.6 earthquake, the characteristics of spatio-temporal evolution and sub-instability of anomalies before the earthquake are systematically analyzed. The results show that before the Jinggu earthquake, the anomalies in the middle period before the earthquake, especially in the short impending stage, caused by the change of the focal area, are prominent. The anomalies exhibit periodic and quasi synchronous changes, overlapping in the time domain. In terms of spatial distribution, they are mainly concentrated in the range of 0-100 km and 200-300 km, showing a certain of group characteristics, and the anomaly stations are mainly concentrated in southwestern Yunnan to western Yunnan.

The coseismic deformation field of the 2022-01-08 Menyuan earthquake is obtained by DInSAR technology based on Sentinel-1A data. The focal parameters and fault plane slip distribution are determined by using elastic half-space dislocation model and distributed slip model. The deformation field of InSAR ascending and descending orbit is traversed by the Lenglongling fault, and the maximum deformation of line-of-sight direction are 50 cm and 70 cm, respectively. The focal mechanism solution obtained from inversion shows that the strike of fault is 103° and the dip angle is 80°. The coseismic slip distribution is mainly concentrated in the range of 0-15 km, with the average slip of 0.67 m and the maximum slip of 2.45 m, showing a left-lateral strike-slip earthquake. The epicenter is located at 37.72°N, 101.34°E, and the seismic moment released is 1.718×1019 Nm, equivalent to the moment magnitude of 6.9. Based on the results and the regional structure, it is concluded that the seismogenic fault of this earthquake is the Lenglongling fault. It is necessary to pay attention to the seismic hazard in this area based on the analysis of coseismic stress variation of this earthquake.

On February 6, 2023, double M7.8 earthquakes occurred in Türkiye, and the co-seismic response of Shiyan Fangxian well and Zhongxiang Maling well is significantly different. The aquifer permeability coefficient of Maling well is much higher than that of Fangxian well, so the water exchange of well-aquifer system is more frequent and intense due to earthquake waveform. The hydroseismogram amplitude of static level is larger and the duration is longer. The aquifer water flowed to borehole caused by seismic wave. Controlled by the water temperature gradient and water temperature sensor position, the form and duration of water temperature response are different. The aquifer water temperature of Fangxian well is cold water compared with that at 65 m, so the water temperature at 65 m shows a downward step change. The aquifer water temperature is hot water compared with that at 105 m, and the distance is closer, so the water temperature at 105 m shows a upward step change and lasts longer. Under the mixed action of upper cold water and lower hot water, the water temperature at 290 m of Maling well is more affected by the upper cold water, so the co-seismic response at 290 m shows a downward step change. The water temperature sensor at 346 m is located in the hot aquifer at the bottom of well, so the co-seismic response shows a upward step change and lasts longer.

The fault activity characteristics of north and middle sections of Xiannüshan fault zone are analyzed by using the cross-fault leveling data of the Three Gorges for several years. The results show that the Xiannüshan fault zone has segmented activity characteristics. The north section is compressional reverse fault, and its activity is weak, while the middle section is tensional normal fault, and its activity is stronger. In addition, the fault activity of north section of Xiannüshan fault zone is influenced by the impoundment of the Three Gorges reservoir and earthquake activities.

Based on the normalized landslide displacement monitoring data and real-time hydrological measurement data and correlation analysis, the results show that displacement and landslide seepage, tunnel water level, daily rainfall are positively correlated, and the changes of seepage, tunnel water level and daily rainfall are synchronous. There is a certain lag between daily rainfall and displacement, and the degree of influence on displacement is in the following order: tunnel water level>seepage＞daily rainfall. The cusp catastrophe model and swallowtail catastrophe model are established, and the results show that both of them have a certain response to the landslide stability, and the former is better.

We analyze the issue of conducted emission exceeding the standard in the identification test of seismic shutdown triggering device, and provide a detailed analysis from disturbance source localization. The specific rectification plan is provided and verified in third-party testing agency, meeting the class A limit requirements of group 1 of GB 4824-2019.

A self-calibration method and damping ratio calibration calculation step of seismic accelerometer in nuclear power plant are introduced. The structural principle of seismic accelerometer is analyzed, and the transfer function of step signal response is given. Based on this, the self-calibration calculation formula and specific calculation process for damping ratio are provided. The experimental verification of seismic accelerometer prototypes show that the calculation results are consistent with the damping ratio index provided by the equipment manufacturer, and the calculation method has practical value in nuclear power plant engineering applications.

Underground seismometer has become the main means to obtain seismic observation information with high signal-to-noise ratio due to its advantages of being placed underground and its characteristics of avoiding interference from human activities and natural environment. In order to obtain high quality observation data, it is necessary to solve the problem of zero drift of seismometer. The seismometers currently used are mainly based on manual zero adjustment. In order to meet the needs of technological update and adapt to complex environment, this paper develops a set of intelligent leveling device for underground seismometer based on STM32 microcontroller, which can effectively compensate the problem of zero drift of underground seismometer.

We introduce the product output process and instrument intensity algorithm of the Hubei seismic intensity output system. The system achieved rapid output of seismic intensity rapid report results after the Yingcheng M4.9 earthquake, quickly and reliably distinguishing the spatial distribution of ground motion or seismic intensity, providing a more accurate reference basis to estimate the disaster degree, loss assessment, and rescue in different regions.

We introduce the principle of IIR filter and describe the generation of IIR filter in MATLAB. The optimized IIR filter is successfully transplanted into embedded system. After the real seismic data processing by band-pass filtering, the noise is obviously eliminated, and it has a good effect, and can be used in seismic monitoring data filtering.

Based on Xamarin framework, a seismic precursor instrument status viewing APP which can be used on Android platform has been developed by C# language. The software can be installed on Android mobile phones, and the seismic industry network can be accessed through VPN to check the status of precursor instruments anytime and anywhere. The software has network status viewing, current data viewing and all-day data curve plotting functions. The software is easy to operate, friendly and easy to install, and has been used by Fengning seismic station in daily work.

Aiming at the problems of insufficient redundancy, low retrieval efficiency, and poor access mobility in the current centralized storage method of traditional seismic data system，a blockchain-based seismic data mechanism based on the DBFC is designed. Data security access control mechanism for blockchain solutions has been proposed, and the access control process and methods for data security in the seismic industry have been explained to ensure the uniqueness, reliability, and integrity of data area access control permissions. The DBFC-BD data security access control method based on smart contracts is designed to implement an open efficient, and fully transparent access mechanism for big data resources. Practical simulations have shown that this mechanism is stable and reliable, and can effectively contribute to the data security capabilities in the seismic system.

This paper introduces several ways of data acquisition and timing of the extensometer, and how to repair EPD format file after error occurred. The results show that the accuracy of data acquisition and timing can be effectively improved by configuring a reliable IP address for SNTP server. Quickly identifying the equipment running LOG files can facilitate the staff to backtrack and self-check various data acquisition operations.