Earthquake Sequence Research Articles

Earthquake Cycle Mechanics During Caldera Collapse: Simulating the 2018 Kı̄lauea Eruption

AbstractIn multiple observed caldera‐forming eruptions, the rock overlying a draining magma reservoir dropped downward along ring faults in sequences of discrete collapse earthquakes. These sequences are analogous to tectonic earthquake cycles and provide opportunities to examine fault mechanics and collapse eruption dynamics over multiple events. Collapse earthquake cycles have been studied with zero‐dimensional slider‐block models, but these do not account for the complicated interplay between fluid and elastic dynamics or for factors such as the heterogeneous fault properties and non‐vertical ring fault geometries often inferred at volcanoes. We present two‐dimensional axisymmetric mafic piston‐like collapse earthquake cycle models that include rate‐and‐state friction, fully‐dynamic elasticity, and compressible viscous fluid magma flow. We demonstrate that collapse earthquake intervals and magnitudes are highly sensitive to inertial effects, evolving stress fields, fault geometry, and depth‐varying fault friction. Given the consistent earthquake cycles observed in most eruptions, this suggests that ring faults can quickly stabilize and often become nearly vertical at depth. We use the well‐monitored 2018 collapse sequence at Kı̄lauea as a case study. Our model can produce many features of Kı̄lauea seismic and geodetic observations, except for a significant amount of interseismic slip, which cannot be readily explained with simple rate‐and‐state friction parameterizations.

Estimating sliding displacement of slopes induced by earthquake sequences based on the finite element method

After shocks trigger or worsen landslides by exacerbating damage to slopes. In this study, slope sliding displacements induced by seismic sequences were calculated. The combined effects of mainshocks and aftershocks on slope sliding were examined in this study using 273 ground motion records from real seismic sequences. A three-layer clayey slope was modeled in OpenSees. The ground motions were input for dynamic analysis to calculate the corresponding sliding displacements. More than 20% of the seismic sequences caused slope instability. The Arias intensity (Ia) of the mainshock had the strongest correlation with sliding displacements. The strength reduction technique was used for the pseudo-static stability analysis of the slope whose yield acceleration (ky ) value was 0.23g. The Newmark method computed smaller displacements compared to the finite element method which calculated the dynamic behavior of the slope more accurately when Ts/Tm > 0.1. The Ia of the mainshock was the optimal parameter. An empirical model based on finite element numerical analysis was proposed for predicting slope sliding displacements induced by seismic sequences. The predictive model, unlike the traditional rigid sliding block method, prevented some unrealistic assumptions. The proposed model was more conservative than numerical algorithm-based predictive models that compute only the mainshock effect.

Offshore Fault Geometry Revealed from Earthquake Locations Using New State-of-Art Techniques: The Case of the 2022 Adriatic Sea Earthquake Sequence

Abstract Precise hypocenter locations are critical for properly interpreting earthquake occurrence processes. However, when the coverage with seismic stations is unfavorable or sparse, locating precisely earthquake hypocenters, in particular their depth, is challenging. Here we apply a newly developed approach, which uses only two land stations, to the recently occurred 2022 Adriatic Sea offshore earthquake sequence (mainshock of magnitude Mw 5.5) and achieve location results that are comparable to the catalog locations obtained using dozens of stations. First, six events with magnitudes M ≥3.0 were relocated using a travel-time stacking method. Next, using these six earthquakes as reference events, we applied a two-station differential travel-time method to reconstruct the earthquake cluster geometry and locate the remaining events, including the mainshock. The obtained earthquake distribution shows a dipping direction that varies from south to southwest, depending on the choice of the input parameters. Our preferred result shows a cluster dipping at an angle of ∼30° toward the south-southwest. This solution was chosen because the depth of the mainshock hypocenter obtained using the differential-time procedure agrees well with the depth constrained using depth phases. Moreover, the relatively sharp earthquake cluster geometry is in general consistent with the thrust fault structures revealed by a local seismic reflection survey and focal mechanism solutions.

Wasatch Fault Structure from Machine Learning Arrival Times and High-Precision Earthquake Locations

Abstract On 18 March 2020, a magnitude 5.7 earthquake hit the Salt Lake valley in the state of Utah, United States. Using a dense geophone deployment and machine learning (ML), an additional several thousand events were detected and located. Currently, both the mainshock and the majority of the aftershocks are suspected to have occurred on or near a deeper portion of the Salt Lake segment of the Wasatch fault—part of a large range-bounding fault system thought to be capable of generating an Mw 7.2 earthquake. However, a small subset of aftershocks may have occurred on a portion of the more steeply, eastward dipping, and poorly understood West Valley fault. Unfortunately, the catalog locations and lack of focal mechanisms for this subset of aftershocks provide only a crude constraint on the true fault structure. To better illuminate fault structure, we relocate the ML-generated catalog with a range of magnitudes from −2 to 4.6, using: (1) NonLinLoc, a nonlinear location algorithm, (2) source-specific station terms, and (3) waveform coherence. We further compute first-motion focal mechanisms for 68 events. Results of the relocation suggest a simpler, minimally listric Wasatch fault geometry, contrary to what has been previously proposed. We also find that analysis of the focal mechanisms and waveform similarity indicates minimal event similarity throughout the Magna sequence, suggesting a highly complex and heterogeneous rupture zone, as opposed to rupture on a single plane. These findings suggest an increased seismic hazard due to the overall shallowness of the earthquake sequence and highly varied rupture mechanisms.

The performance of Karasu Bridge following the February 6, 2023 Kahramanmaras-Turkiye earthquake sequence

The evaluation liquefaction-induced excessive ground displacements of the approach embankments of the Karasu Bridge, as surveyed following the Pazarcik M7.8 and Ekinozu-Elbistan M7.6, Kahramanmaras-Turkiye earthquakes on February 6, 2023, is presented. The Karasu Bridge, located on the Karasu River, connects the metropolitan city of Hatay and the State Hospital. The approach embankments of the bridge are underlain by layers of low to high plasticity stiff clay and liquefaction susceptible clayey and silty medium dense sand units. Specifically, the non-plastic silty sands with fines contents ranging from 21% to 42%, were evaluated as the critical (liquefied) soil units during the Pazarcik earthquake. Liquefaction triggering assessments, following the procedure outlined by Cetin et al. (2018), estimated factor of safety against liquefaction <1.0, confirming the surface manifestations of liquefaction at the site. Empirical approaches suggested by Hamada et al. (1986) and Youd et al. (2002) predicted lateral ground displacements triggered by liquefaction, averaging 137 cm and 383 cm, respectively. These values are comparable with mapped lateral displacements, which exceeded 150 cm. Volumetric settlement assessments, utilizing the method outlined by Cetin et al. (2009), predicted 14 to 26 cm, approximately one third to half of the mapped settlement values ranging from 40 to 55 cm. The discrepancy is attributed to the three-dimensional nature of site behavior and induced deviatoric strains, contributing to additional settlements beyond the volumetric component.

Time-varying damping ratios and velocities in a high-rise during earthquakes and ambient vibrations from coda wave interferometry

Coda wave interferometry is applied to data from Community Seismic Network MEMS accelerometers permanently installed on nearly every floor of a 52-story steel moment-and-brace frame building in downtown Los Angeles. Wavefield data from the 2019 M7.1 Ridgecrest, California earthquake sequence are used to obtain impulse response functions, and time-varying damping ratios and shear-wave velocities are computed from them. The coda waves are used because of their increased sensitivity to changes in the building’s properties, and the approach is generalized to show that a building’s nonlinear response can be monitored through time-varying measurements of representative pseudo-linear systems in the time domain. The building was not damaged, but temporary nonlinear behavior observed during the strong motions provides a unique opportunity to test this method’s ability to map time-varying properties. Reference damping parameters and velocities are obtained from a month-long period during which no significant seismic activity had occurred. Damping ratios measured over narrow frequency bands increase by up to a factor of 4 over short time durations spanning the main shock, as well as M &gt; 4.5 aftershocks and a foreshock. The largest damping ratio increases occur for the highest frequencies, and the increase is attributed to friction associated with structural and non-structural surface discontinuities which experience relative motion and impact during shaking, resulting in energy loss. Shear-wave velocities in the building’s east–west and north–south directions are found by applying a waveform stretching method to the direct and coda waves. The broadband velocities are reduced by as much as 10% during building shaking, and their restoration to pre-earthquake levels is found to be a function of shaking amplitudes. Until recently, these techniques had been limited by temporal and spatial sparsity of measurements, but in this study, variations of the impulse response functions are resolved over time scales of tens of seconds and on a floor-by-floor spatial scale.

Machine Learning-Based Framework for Failure Forecast and Shear Strength Estimation of Non-Conforming RC Shear Walls

ABSTRACT Earthquake reconnaissance after the recent Kahramanmaras, Turkey, earthquake sequence in February 6, 2023 has shown that the majority of the reinforced concrete (RC) structural elements do not comply with the Turkish Building Earthquake Code (TBEC 2018) requirements. Accurate estimation of the actual strength of existing non-compliant RC structural members is critical to accomplish reliable earthquake performance assessments. This study aims to propose a machine learning-based framework to establish a realistic failure forecast as well as an accurate shear strength estimation depending on the expected failure modes of such walls. To achieve this, shear wall design properties are assigned as inputs whereas failure mode and shear strength were designated as outputs for the corresponding classification and regression problems, respectively. Widely used machine learning methods, namely: Ridge Linear Regression, Logistic Regression, Multi-layer Perceptron, Support Vector Machine, Random Forest, XGBoost, LightGBM, and CatBoost are employed using a database consisting of 432 non-conforming shear walls. The data is randomly split to train and test sets (80% and 20%, respectively) to develop the predictive models and to evaluate model performances, respectively. Performance metrics (e.g. R 2 , RMSE) are evaluated over a hundred random splits to ensure robustness. The proposed CatBoost-based models achieve overall accuracies above 90% for both failure prediction and shear strength estimation. The proposed framework is believed to be a promising tool for earthquake engineers for practical and accurate failure mode forecast and shear strength estimation of non-compliant RC shear walls.

Erratum to The Influence of a Transitional Stress Regime on the Source Characteristics of Induced Seismicity and Fault Activation: Evidence from the 30 November 2018 Fort St. John ML 4.5 Induced Earthquake Sequence

<i>Erratum to</i> The Influence of a Transitional Stress Regime on the Source Characteristics of Induced Seismicity and Fault Activation: Evidence from the 30 November 2018 Fort St. John ML 4.5 Induced Earthquake Sequence

Regional and Site-Specific Ground Motion Model for Probabilistic Seismic Hazard Analysis in Taiwan: A Case Study of I-Lan

In this study, a probabilistic seismic hazard analysis (PSHA) using a traditional approach with a simple logic tree that handles a single-site sigma is developed to present a site-specific ground motion hazard. The analysis relies on the accelerometer data collected from the I-Lan Plain, a deep sedimentary basin in Northeastern Taiwan where hundreds of earthquake sequences (with [Formula: see text] = 4.0–7.6) were recorded by the Taiwan Strong Motion Instrument Program (TSMIP) network between 1992 and 2016. The performance of PSHA on soil and hard sites is evaluated from two representative instrumented sites (ILA048 and ILA025), using residual measures available from a ground motion model (GMM) developed by Phung et al. [ 2023 ] (referred to as Ph23), from which the uncertainties in site terms ([Formula: see text] and single-site sigma ([Formula: see text] are estimated. We address key conceptual issues in the current PSHA approach and introduce a new region- and site-specific PSHA approach in which (1) site-to-site variability ([Formula: see text] is estimated as a random variance in a mixed effects GMM regression and (2) the GMM site-specific single-site sigma ([Formula: see text] is replaced with a generic site-corrected aleatory variability ([Formula: see text]). Comparison of the region- and site-specific hazard curves from our method against the traditional method estimates at two well-recorded sites in the I-Lan region shows an approximate 50% difference in prediction ground motion values considering for 2% and 10% probability of exceedance in 50 years.

The Observed and Simulated Site Effects at the Selected Regions Influenced by 2023 Turkey Earthquake Sequences: A Preliminary Evaluation

ABSTRACT This study offers an initial evaluation of site effects within regions impacted by the February 2023 earthquakes in Turkey. It develops a preliminary response spectrum site amplification model, alongside probabilistic seismic hazard analysis and 1D site response analyses (SRAs) specifically focused on a site in Hatay. The model suggests higher site factors in softer sites for 0.2 sec, contrasting with other conditions. Results demonstrate that surface spectra derived from 1D SRAs and site-specific uniform hazard spectrum are consistently lower than Turkish Earthquake Building Code (TEBC) design spectrum across all considered periods, indicating the necessity for a detailed reassessment of TEBC specifications.

Comparison of Various Input Energy Spectra for the February 6th, 2023, Kahramanmaraş Earthquake Sequence

ABSTRACT This study aims to evaluate the success of various seismic input energy spectra equations in capturing the energy content of the ground motion records of the Türkiye earthquakes since the acceleration response spectra of some records exceeded the design spectra. Although most existing spectra had limited success, especially near the corner period, some recent equations yielded accurate results. Based on the obtained results, it is envisaged that the energy-based seismic design concept will have the maturity to be included in the next-generation seismic design codes as a reliable alternative to the current approaches.

Mid-ocean ridge unfaulting revealed by magmatic intrusions.

Mid-ocean ridges (MORs) are quintessential sites of tectonic extension1-4, at which divergence between lithospheric plates shapes abyssal hills that cover about two-thirds of the Earth's surface5,6. Here we show that tectonic extension at the ridge axis can be partially undone by tectonic shortening across the ridge flanks. This process is evidenced by recent sequences of reverse-faulting earthquakes about 15 km off-axis at the Mid-Atlantic Ridge and Carlsberg Ridge. Using mechanical models, we show that shallow compression of the ridge flanks up to the brittle failure point is a natural consequence of lithosphere unbending away from the axial relief. Intrusion of magma-filled fractures, which manifests as migrating swarms of extensional seismicity along the ridge axis, can provide the small increment of compressive stress that triggers reverse-faulting earthquakes. Through bathymetric analyses, we further find that reverse reactivation of MOR normal faults is a widely occurring process that can reduce the amplitude of abyssal hills by as much as 50%, shortly after they form at the ridge axis. This 'unfaulting' mechanism exerts a first-order influence on the fabric of the global ocean floor and provides a physical explanation for reverse-faulting earthquakes in an extensional environment.

Double-Vergent Plate Boundary Faults and Triggered Coseismic Rupture of the 2022 Chihshang Doublet Earthquake Occurred in Eastern Taiwan

Abstract The earthquake doublet of Mw 6.5 and 6.9 occurred along the west-dipping Central Range fault (CRF) adjacent to the east-dipping creep segment of the Longitudinal Valley fault in eastern Taiwan on 17–18 September 2022. The faulting model derived from the Interferometric Synthetic Aperture Radar and Global Positioning System observation suggests that the west-dipping CRF rupture is responsible for the two mainshocks. Meanwhile, the two major earthquakes resulted in ∼100 km of fault slip along the double-convergent plate boundary faults near the Longitudinal Valley in eastern Taiwan. The 2022 Chihshang earthquake sequence filled the seismic gap of the CRF located between the 2006 ML 6.1 Taitung earthquake and the 2013 ML 6.1 Ruisui earthquake. Finally, the 2022 Chihshang earthquake sequence increased the Coulomb failure stress in the southernmost segment of the CRF, which may cause a higher seismic potential in the future.

The relationship between kinematics and fault geometry for surface coseismic ruptures on across-strike faults: New observations of slip vectors and displacements along the Pisia and Skinos faults from the 1981 Eastern Gulf of Corinth, Greece earthquakes

The relationships between kinematics and fault geometry for the coseismic ruptures from the 24th and February 25, 1981 earthquake sequence in the eastern Gulf of Corinth (Ms 6.7 and 6.4) are analysed. The two earthquakes ruptured faults located across strike rather than along strike as typifies other earthquake sequences. In detail, surface ruptures formed on the sub-parallel Pisia and Skinos Faults, with an 8 km along-strike overlap zone, separated across strike by < 2 km. The largest coseismic offsets occurred in the overlap zone. The 41-year-old ruptures are still well preserved as bedrock fault plane lichen-free stripes and colluvial ruptures, allowing detailed structural mapping at 213 rupture localities. A comparison between our measurements and Jackson et al. (1982) showed no overall consistent signal of post-seismic slip as some of our measurements were greater and some smaller than those recorded in 1981. The ruptures produced a single maximum asymmetric profile (Pisia: maximum throw of 223 cm) and a double maxima profile (Skinos: maximum throw of 109 cm and 130 cm). The shapes of the profiles differed in previous earthquakes on these faults, as evidenced by an older lichen-free stripe, implying non-characteristic earthquakes. Summing the two overlapping throw profiles across-strike reveals a single maximum symmetric bell-like profile. Using the above observations on coseismic offsets, kinematic information, and the geometry of faults, a rupture scenario has been proposed in terms of fault bends and corrugation orientations which suggests that parts of each fault may have ruptured in each earthquake.

Exploring inferred geomorphological sediment thickness as a new site proxy to predict ground-shaking amplification at regional scale: application to Europe and eastern Türkiye

Abstract. To test whether a globally inferred sediment thickness value from geomorphological studies can be used as a proxy to predict earthquake site amplification, we derive site-amplification models from the relation between empirical amplification for sites in Europe and Türkiye and the geomorphological sediment thickness. The new site-amplification predictions are then compared to predictions from site-amplification models derived using the traditional site proxies, VS30 inferred from slope, slope itself, and geological era and slope combined. The ability of each proxy to capture the site amplification is evaluated based on the reduction in site-to-site variability caused by each proxy. The results show that the highest reduction is caused by geological era and slope combined, while the geomorphological sediment thickness shows a slightly larger or equal reduction in site-to-site variability as inferred VS30 and slope. We therefore argue that including geology and geomorphology in site-amplification modelling on regional scale can give an important added value and that globally or regionally inferred models for soil and sediment thickness from fields beyond engineering seismology can have a great potential in regional seismic hazard and risk assessments. Furthermore, the differences between the site-amplification maps derived from different proxies capture the epistemic uncertainty of site-amplification modelling. While the different proxies predict similar features on a large scale, local differences can be large. This shows that using only one proxy when predicting site amplification does not capture the full epistemic uncertainty, which is demonstrated by looking into detail on the site-amplification maps predicted for eastern Türkiye and Syria, where the devastating Kahramanmaraş earthquake sequence occurred in February 2023.

The 2020 Mw 6.5 Stanley, Idaho, Earthquake and Aftershock Sequence: Complex Faulting at the Northern End of the Basin and Range Province

ABSTRACT The magnitude 6.5 Stanley, Idaho, earthquake occurred on 31 March 2020 in a sparsely populated region north of the Sawtooth normal fault. We used seismic data from temporary and permanent stations to derive a 1D velocity model and relocate 1401 M ≥ 2.4 earthquakes with hypoDD, including a foreshock, the mainshock, and 3 yr of aftershocks. We used broadband data to determine seismic moment tensors for 173 Mw≥3.1 earthquakes. Combining locations and mechanisms shows the mainshock ruptured an unmapped north-trending, steeply west-dipping, left-lateral strike-slip fault. Rupture initiated near the bottom of the seismogenic zone and propagated upward and bilaterally for ∼20 km north and ∼3–5 km south, where the fault likely ends and deformation changes to extension. There, the rupture may have jumped west to another unmapped blind fault accommodating oblique extension. Support for a late mainshock rupture on a northwest-trending, likely east-dipping fault comes from normal faulting aftershocks. The total rupture length is ∼25–30 km, because oblique fault activity ends at the latitude of the northern terminus of the Sawtooth fault, but its trace, if it reached the surface, would be ∼6 km to the west. The Sawtooth fault was not active, even though aftershock clusters indicate that short strike-slip and normal faults are abundant in its footwall and hanging wall. Extension in the northern Basin and Range seems to terminate where major normal faults reach the inactive Eocene Trans-Challis fault system (TCFS), suggesting the TCFS exerts structural control. The deformation north of the TCFS is low, and the strike-slip character was unknown before the Stanley earthquake. Faults rupturing in the Stanley earthquake lack surface expression and are immature with low cumulative displacement. Complex transitions between tectonic regimes are common and may result in blind ruptures on unknown, immature faults, posing an underrated hazard.

Analysis of impulsive ground motions from February 2023 Kahramanmaraş earthquake sequence

AbstractOn the 6th of February 2023, a large magnitude earthquake (Pazarcık earthquake), $$M_{w}=$$ M w = 7.7, occurred in southeast Türkiye, which caused significant destruction in Türkiye and Syria. Relatively large magnitude aftershocks followed the main shock, and after 9 hours of the main event, another large magnitude earthquake (Elbistan earthquake) occurred, $$M_{w}=$$ M w = 7.6, on a nearby fault. This study analyzes the near-fault seismic signals from earthquakes larger than 5.5 recorded between the main shock and the 31st of March 2023. More than 60 impulsive motions are detected in 3 earthquakes, mostly concentrated in the Pazarcık and Elbistan earthquakes. In the Pazarcık earthquake, many impulsive motions are recorded in near-fault stations with periods of up to 14 s. In contrast, in the Elbistan earthquake, impulsive motions are spatially distributed, with pulse periods of up to 11 s and at distances greater than 150 km. Pulse periods mostly correlate with the magnitude of the earthquake, but pulse probability models do not predict impulsive motions over long distances. The presence of strong impulsive motions in vertical components is also observed. For both earthquakes, peak ground velocities (PGVs) are larger than predicted by ground motion prediction equations. The observation of long-period, large amplitude signals may indicate the presence of a directivity effect for both earthquakes. In some stations, spectral periods exceed the 2018 Turkish building design codes for long periods ($$\ge$$ ≥ 1 s).

Seismic Response of Vertical Hybrid Concrete/Steel Frames Considering Soil–Structure Interaction

The aim of this study is to investigate the seismic behavior of concrete/steel mixed structures. In engineering praxis, many buildings consist of two parts: one made of reinforced concrete and the other made of steel. There are several difficulties in the code-based seismic design of these structures due to the different dynamic responses of each discrete part. Seismic design codes, such as the IBC and Eurocode 8, do not provide instructions for structures consisting of two parts. In addition, they use a single-loading scenario, but there are many locations that are affected by more than one earthquake in a short period. Another drawback is that recent provisions do not consider soil–structure interaction effects. The specific issue addressed here is the seismic response of mixed structures, which is evaluated through inelastic time–history analysis. More specifically, the response indices involve height-wise distributions for peak interstory drift ratios, maximum floor horizontal displacements, maximum floor accelerations, and plastic hinge formations in the frame elements when they are subjected to seismic sequences of earthquakes, as well as in far fault ground motions for different soil types. The results reveal that sequential ground motions lead to increased displacement demands, and they affect the permanent displacements. This phenomenon appears in both cases of stiff and flexible soil, as well as for both regular and irregular frames. It is found that soil–structure interaction generally leads to lower values of IDR, and maximum horizontal displacement and acceleration in comparison with the case of rigid soil assumptions.

Laboratory Earthquake Ruptures Contained by Velocity Strengthening Fault Patches

AbstractMany natural faults are believed to consist of velocity weakening (VW) patches surrounded by velocity strengthening (VS) sections. Numerical studies routinely employ this framework to study earthquake sequences including repeating earthquakes. In this laboratory study, we made a VW asperity, of length L, from a bare Poly(methyl methacrylate) PMMA frictional interface and coated the surrounding interface with Teflon to make VS fault sections. Behavior of this isolated asperity was studied as a function of L (ranging from 100 to 400 mm) and the critical nucleation length, , which is inversely proportional to the applied normal stress (2–16 MPa). Consistent with recent numerical simulations, we observed aseismic slip for &lt; 2, periodic slip for 2 &lt; &lt; 6, and non‐periodic slip for 10 &lt; . Furthermore, we compared the experiments where L was contained by VS material to standard stick‐slip events where L was bounded by free surfaces (i.e., L = the total sample length). The free surface case produced ∼10 times larger slip during stick‐slip events compared to the contained fault ruptures, even with identical . This disparity highlights how standard, complete‐rupture stick‐slip events differ from contained events expected in nature, due to both the free surface conditions and the heterogeneous normal stress along the fault near the free ends, as confirmed by Digital Image Correlation analysis. This study not only introduces the Teflon coating experimental technique for containing laboratory earthquake ruptures, but also highlights the utility of as a predictive parameter for earthquake behavior.

Characteristic Analysis of the MS6.0 Ma'erkang Earthquake Sequence on Jun. 10, 2022

On June 10, 2022, the MS6.0 Ma'erkang earthquake sequence occurred in the Bayan Har block. In this paper, the temporal and spatial distribution and attenuation characteristics of earthquake sequence is analyzed based on the regional structure, the temporal and spatial distribution of earthquake sequence, the focal mechanism solution, and the parameters of earthquake sequence, using the data of Sichuan Seismic Network and the temporary stations incorporated into the network. The results show that: (1) The MS6.0 Ma'erkang earthquake sequence is generally distributed in NW-SE direction, and the long axis of this series is basically consistent with the nearby Songgang fault. (2) As the earthquake sequence is formed by three large events with MS ≥5.0, the frequency of small earthquakes in the earthquake sequence area generally attenuates relatively slowly, while the activity level (magnitude) of aftershocks attenuates rapidly. (3) After the MS5.2 earthquake, the sequence parameters obtained show that the h-value is 1.09 and the p-value is stable at 1.02, indicating that the intensity and frequency attenuation of the earthquake sequence are gradually stable and tend to be normal. The b-value is 0.95, indicating that the maximum aftershock magnitude of the series is estimated to be ML5.1, and the b-value gradually tended to be stable, indicating that the stress in the region gradually tended to be balanced after the MS5.2 earthquake. The MS4.4 (ML5.0) earthquake that occurred at 4:37 on June 10 (local time) is the largest aftershock after the MS5.2 earthquake in the sequence. (4) The Songgang fault with NW-SE trend is presumed to be the main seismogenic tectonics, but the migration of three earthquakes with MS≥5.0 may also indicate that the Songgang fault is not a single seismogenic tectonics, which requires further field scientific investigation and analysis.