We considered various non‐uniformities such as branch faults, rotation of stress field directions, and changes in tectonic environments to simulate the dynamic rupture process of the 6 February 2023 ...Mw 7.8 Kahramanmaraş earthquake in SE Türkiye. We utilized near‐fault waveform data, GNSS static displacements, and surface rupture to constrain the dynamic model. The results indicate that the high initial stress accumulated in the Kahramanmaraş‐Çelikhan seismic gap leads to the successful triggering of the East Anatolian Fault (EAF) and the supershear rupture in the northeast segment. Due to the complexity of fault geometry, the rupture speed along the southeastern segment of the EAF varied repeatedly between supershear and subshear, which contributed to the unexpectedly strong ground motion. Furthermore, the triggering of the EAF reminds us to be aware of the risk of seismic gaps on major faults being triggered by secondary faults, which is crucial to prevent significant disasters.
Plain Language Summary
On 6 February 2023, the south‐central Türkiye was hit by two major earthquakes with magnitudes of Mw 7.8 and Mw 7.6 respectively. Among them, the complex rupture process and unexpected ground motion of the Mw 7.8 event attracted the attention of seismologists. In this paper, the 3D dynamic rupture process of this mainshock is simulated based on complex multi‐fault system and heterogeneous initial stress. And the simulation results are in good agreement with the observations. Our results show that high initial stress is required for the EAF to be triggered. The supershear rupture occurred only in certain fault segments and is unable to sustain itself in a significant area on the fault due to the along‐strike variations in fault geometry and strength. More importantly, the dynamic model suggests that we must be alert to the risk of major fault being triggered by earthquakes on nearby small faults, especially when there are seismic gaps on the major fault.
Key Points
The high initial stress accumulated in the seismic gap leads to the successful triggering of the East Anatolian Fault
The change of fault geometry in the southwest segment prevented the sustained supershear rupture
The risk of earthquake nucleation on the secondary fault triggering the major fault rupture and the related disaster was highlighted
Flavonoids have a variety of physiological activities such as anti-free radicals, regulating hormone levels, antibacterial factors, and anti-cancer factors, which are widely present in edible and ...medicinal plants. Real-time detection of flavonoids is a key step in the quality control of diverse matrices closely related to social, economic, and health issues. Traditional detection methods are time-consuming and require expensive equipment and complicated working conditions. Therefore, electrochemical sensors with high sensitivity and fast detection speed have aroused extensive research interest. Carbon nanomaterials are preferred material in improving the performance of electrochemical sensing. In this paper, we review the progress of electrochemical sensors based on carbon nanomaterials including carbon nanotubes, graphene, carbon and graphene quantum dots, mesoporous carbon, and carbon black for detecting flavonoids in food and drug homologous substances in the last four years. In addition, we look forward to the prospects and challenges of this research field.
SUMMARY
Surface topography has been considered a difficult task for seismic wave numerical modelling by the finite‐difference method (FDM) because the most popular staggered finite‐difference scheme ...requires a rectilinear grid. Even though there are numerous collocated grid schemes in other computational fields that could be used to solve the first‐order hyperbolic equations, the lack of a stable free‐surface boundary condition implementation for curvilinear grids also obstructs the adoption of curvilinear grids in seismic wave FDM modelling. In this study, we use generalized curvilinear grids that can fit the surface topography to discretize the computational domain and describe the implementation of a collocated grid finite‐difference scheme, a higher order MacCormack scheme, to solve the first‐order hyperbolic velocity‐stress equations on the curvilinear grid. To achieve a sufficiently accurate and stable free‐surface boundary condition implementation on the curvilinear grids, we propose the traction image method that antisymmetrically images the traction components instead of the stress components to the ghost points above the free surface. Since the velocity derivatives at the free surface are provided by the free‐surface condition, we use a compact scheme to compute the velocity derivatives near the free surface and avoid the use of velocity values on the ghost points. Numerical tests verify that using the curvilinear grid, the collocated finite‐difference scheme and the traction image technique can simulate seismic wave propagation in the presence of surface topography with sufficient accuracy.
Epithelial-mesenchymal transition (EMT) is critically involved in a variety of biological processes. Electrochemical sensing offers potential to develop more effective technology for EMT detection. ...In this study, by using the unique performance of quantum dot (QD)-nanocomposite materials, we establish an electrochemical biosensor that can specifically detect the change of E-cadherin and analyze different stages of EMT. The signal for EMT is largely magnified due to the transmission of molecular information to the electronic device. In addition, differential pulse voltammetry reveals that the response of the electrochemical signals is rapid and sensitive, due to the synergistic effect of QDs and carbon nanotube-gold nanoparticles. Our study thus suggests that electrochemical sensing is an effective technology for detecting EMT and may have broad applications in analyzing various cell type transitions.
SUMMARY
For simulating the dynamic rupture process in earthquake scenarios, the stress distribution along the fault remains unclear owing to a lack of direct measurements. Regional stress fields are ...often resolved onto the fault plane to determine the stress distribution along it. To overcome this limitation, we considered different interseismic locking models to better constrain the actual stress distribution. Specifically, we took the Suoerkuli section in the middle of the Altyn Tagh fault, China, and conducted dynamic rupture simulations to obtain possible earthquake scenarios. The surface rupture length and moment magnitude obtained from the simulations were consistent with those of historical earthquakes. Compared with the traditional stress field resolution method, our approach led to better constrained fault rupture extent and distribution characteristics of regional intensity, thereby avoiding overestimations of earthquake damage. We conclude that examining regional seismic hazards and risks based on seismic dynamic rupture simulations that account for the locking ratio of the fault plane is advantageous, and should be encouraged.
The 2016 Mw 5.9 Menyuan earthquake occurred near the Haiyuan fault system in the northeastern Tibetan plateau. Although some kinematic properties of this event have been investigated, more dynamic ...properties still need to be clarified. First, we use the empirical Green's function method to obtain this event's apparent source time functions (ASTFs), which present a bell shape with a duration of 3s and corresponding smooth spectra. We then conduct dynamic rupture simulations, which are well constrained by the seismic and geodetic observations, to explore more in‐depth source properties. The results show that the characteristics of ASTFs can be explained by the self‐arresting rupture model, which implies that the rupture propagation of this event may spontaneously terminate before reaching the barriers. This result suggests that the initial conditions when this earthquake nucleated may have controlled the rupture process. Our work contributes to understanding the stopping mechanism of some moderate earthquake ruptures.
Plain Language Summary
A quantitative understanding of what controls earthquake rupture propagation is important, helping to estimate the eventual magnitude of a future earthquake and thus has significant implications for earthquake hazard assessment. Previous studies indicate that the complex fault geometry and the heterogeneous material properties of the fault zone can influence earthquake rupture propagation. In this study, we first use the empirical Green's function approach to obtain the single‐peak apparent source time functions for the 2016 Mw 5.9 Menyuan earthquake, and the corresponding spectra have no spectral troughs. We then conduct the spontaneous dynamic rupture simulations, which are well constrained by the geodetic and seismic observations, to reveal more source properties. The features of apparent source time functions can be well explained by the self‐arresting rupture process, which implies that the rupture propagation might spontaneously stop without external interference. This result indicates that this earthquake's rupture propagation might have been deterministic by the initial conditions in which it prepared for rupture.
Key Points
The apparent source time functions (ASTFs) of the 2016 Mw 5.9 Menyuan earthquake display a bell shape and corresponding smooth spectra
The features of ASTFs can be explained by the self‐arresting rupture model, implying that the rupture propagation might spontaneously stop
The dynamic rupture simulations are constrained by the interferometric synthetic aperture radar data and strong ground motion observations
In recent years, the increasing incidence and mortality of cancer have inspired the development of accurate and rapid early diagnosis methods in order to successfully cure cancer; however, ...conventional methods used for detecting tumor cells, including histopathological and immunological methods, often involve complex operation processes, high analytical costs, and high false positive rates, in addition to requiring experienced personnel. With the rapid emergence of sensing techniques, electrochemical cytosensors have attracted wide attention in the field of tumor cell detection because of their advantages, such as their high sensitivity, simple equipment, and low cost. These cytosensors are not only able to differentiate tumor cells from normal cells, but can also allow targeted protein detection of tumor cells. In this review, the research achievements of various electrochemical cytosensors for tumor cell detection reported in the past five years are reviewed, including the structures, detection ranges, and detection limits of the cytosensors. Certain trends and prospects related to the electrochemical cytosensors are also discussed.
We combine measurements of ground deformation from Synthetic Aperture Radar images, high‐rate Global Navigation Satellite System and tele‐seismic waveforms to study the rupture kinematics of the ...Madoi Earthquake, which occurred in eastern Tibet on 21 May 2021 and reached a moment magnitude Mw 7.4. The data show nearly pure left‐lateral motion along a 170 km long rupture and a total duration of 36 s. The earthquake initiated near the middle of the main segment and evolved in a bilateral slip pulse rupture which propagated at a sub‐Rayleigh speed of 2.6–2.8 km/s. In our model, slip is concentrated at depth of less than ∼15 km and reaches a maximum of 4.2 m. The rupture arrested ∼10 s after branching on the extensional splay faults at both extremities. The branching onto the splay faults and the eventual arrest of the rupture is used to provide constraints on the fault frictional properties.
Plain Language Summary
The M7.4 Madoi Earthquake, which occurred in eastern Tibet on 21 May 2021 is the largest event since the 2008, M8.0 Wenchuan earthquake. It therefore generated widespread interests among the Chinese public and scientific community. Here, we model the temporal evolution of fault slip during the earthquake using geodetic and seismic observations. Our study reveals a slip‐pulse that ruptured a 170 km long fault system, extending from the surface to about 15 km at depth, with horizontal shear slip of up to 4.2 m. The rupture initiated near the middle of the ruptured fault, propagated bi‐laterally along the fault trace, and ended after branching on splay‐faults. Forking seems to have arrested the rupture. The Madoi Earthquake relates to the eastward extrusion of Tibet which is driven by the northward indentation of India into Eurasia.
Key Points
The 2021 Mw 7.4 Madoi Earthquake ruptured bilaterally for about 170 km with most of slip being concentrated at less than 15 km depth
The rupture was arrested after propagating on splay faults
Propagation along the most misoriented splay fault suggests a dynamic friction possibly as low as 0.05
SUMMARY
A deep understanding of earthquake physics requires a large amount of numerical simulations on seismic wave propagation and dynamic rupture. However, the corresponding intensive computational ...expense of simulations at traditional CPU (central processing unit) platforms make related researches time-consuming. There are many mature graphics processing unit (GPU) programs that can dramatically accelerate the calculation of seismic wave propagation. Unfortunately, there are few discussions about GPU implementations for rupture dynamics. In this work, we extend our 3-D curved-grid finite-difference method (CG-FDM) for rupture dynamics to the GPU platform using the CUDA (compute unified device architecture) programming language. By taking advantage of the new features of the NVIDIA Volta architecture, we implement the GPU-based program for rupture dynamics that is not only efficient but also easy to maintain. The GPU-based CG-FDM program is two orders of magnitude faster than our previous serial CPU-based program and still has a considerable advantage compared with the parallel one. The reliability and correctness of the program are carefully examined by the comparisons of the benchmarks from the ‘Southern California Earthquake Center/U.S. Geological Survey (SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise’. The performance improvements of the GPU-based CG-FDM can save a lot of computing time, allowing researchers to perform much more numerical simulations of rupture dynamics to reveal more details of earthquake physics.
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