Search

Science and Technology Conference (SnT) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is committed to advancing the scientific and technological progress of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), relying on scientific and technological innovation to strengthen the treaty verification system capabilities of CTBT and accelerating the progress of its entry into force. As seismology is an important means for nuclear-test-ban monitoring, and the scientific advances of the SnT conference is helpful to review the development of earthquake science and technology, this paper systematically analyzes the scientific topic setting and the advances of seismic event discrimination research in the SnT conference. The analysis showed that the themes of “the earth as a complex system” and “advances in sensors, networks and processing”, as well as the seismological approaches of the nuclear-test-ban monitoring, attracted more attention. Seismic event discrimination remains a critical CTBT-related seismology problem, and the same is the focus of attention in the applied research on the North Korean nuclear test series, while new technologies such as deep learning and machine learning have shown a rapid development trend in event discrimination research.

On 23 February 2023, an Mw 6.8 earthquake struck the border of Tajikistan and Xinjiang China, the source mechanism remains controversial according to different seismic inversions. To better comprehend the source characteristics and the surface deformation pattern, we used the ascending and descending orbital Sentinel-1A SAR data to obtain the coseismic deformation of this earthquake based on the traditional two-pass differential interferometric synthetic aperture radar (InSAR). The source model is inverted from the InSAR coseismic deformation results. The possible Coulomb Failure Stress (CFS) transfer is analyzed based on the preferred source model. The results illustrate that the earthquake ruptured a blind left-lateral strike-slip fault of strike 28.1° with a maximum slip of 1.53 m and the total geodetic moment is 1.99 × 1019 N·m (Mw 6.83). The strike direction and the fault characteristics suggest the Seismogenic fault is a secondary fault of the Sarez–Karakul Fault System. The 2015 Mw 7.2 Sarez Earthquake plays a triggering role in the occurrence of the 2023 Tajikistan earthquake. Earthquake hazard on Sarez–Karakul Fault System and Sarez–Murghab Thrust System is enhanced due to the Coulomb stress loaded by the Tajikistan earthquake.

North Korea successively conducted five large-scale nuclear tests on May 25, 2009, February 12, 2013, January 6, 2016, September 9, 2016 and September 3, 2017, respectively, since their first underground nuclear test on October 9, 2006. Because the focal mechanisms of nuclear explosions are different from those of natural earthquakes, the seismic waves generated by nuclear explosions can be used to monitor nuclear tests. The seismological research on nuclear tests has always been the focus of domestic and international experts. This paper summarizes the relevant seismological research progresses on North Korea's nuclear tests in recent years in the aspects of event location, discrimination, and yield and burial depth. This paper then uses the bibliometric method to analyse the relevant seismological research status on North Korea's nuclear tests. The comprehensive results show that the main research directions of relevant seismological research based on North Korea's nuclear tests in recent years are nuclear test location, yield estimation, and burial depth estimation.

The correlation between seismic and acoustic signals can be used to quantify the influence of earthquake ground motion on the output signals of infrasound sensors and thus evaluate the performance of infrasound sensors under field conditions. However, there have been relatively few studies, and earthquakes considered in those studies are large magnitude events. There remains a need to quantify correlation mechanisms at high frequencies using small earthquakes. In this study, we utilize a collocated seismoacoustic station BJT and a six-element infrasound array DQS to study different coupling mechanisms for infrasound sensors. From 2019 to 2021, 11 and 37 small magnitude earthquakes were detected by BJT and DQS, respectively. Seismoacoustic signals from these small magnitude earthquakes are used to compute the seismoacoustic spectral ratio and the observed spectral ratios are then compared with theoretical estimates. For local seismic-to-acoustic coupling (local infrasound), the highly local pressure field induced by high-frequency ground motion and the separation between seismoacoustic sensors reduce seismic and acoustic signal correlation, which prevents the use of small earthquakes in current studies. The seismic sensitivity of the infrasound sensor, MB3a is shown to be for ground acceleration or for ground velocity and may be an important source of high-frequency noise for an infrasound station using this sensor. Furthermore, an empirical relation is developed to constrain the characteristics of earthquakes that can generate coupled signals on the infrasound sensor. Our study complements previous work and provides insight into the improved interpretation of infrasound signals and methods of seismoacoustic station calibration. [ABSTRACT FROM AUTHOR]