As infrastructure-as-a-service clouds quickly grow, an increasing number of businesses and people are moving their application development to the cloud. The purpose of the research is to solve the ...problem of identifying memory anomalies in cloud virtual machines and improve the accuracy of the model in detecting abnormal situations. This paper presents a model for detecting virtual machine anomalies in IaaS cloud platform. The model considers the unique properties of monitoring metrics as time-series data and proposes an approach based on four important virtual machine monitoring metrics. The study also develops an adaptive anomaly detection system based on deep Q-network algorithms and migration learning principles for the variety of VM monitoring data in the cloud. The testing findings reveal that utilizing a Zoom layer with a 2-kernel size can increase detection accuracy to 96.7%. This demonstrates that a portion of the experimental data can extract the temporal features using the Zoom layer and different kernel sizes. The research model for anomaly detection had a classification accuracy of 99.8%. The deep Q-network model’s final anomaly detection accuracy varies from 96.7 to 98.6%. The outcomes of the research improved the system’s security and dependability, showed the worth of the overall framework design, and significantly decreased the number of resources needed for system operation and maintenance.
Both the rich mineralization in the Lower Yangtze Block (LYB) and the post-collisional mafic rocks in the Dabie Orogen (DBO) are closely related to the Cretaceous magmatism in east-central China. ...Various geodynamic models have been proposed for explaining the mechanism of the Cretaceous magmatism, but these models are controversial and even contradictory with each other, especially on the mechanism of adakites. A unified geodynamic model is required for explaining the magmatism in east-central China, in particular, the spatial and temporal correlations of magmatic activity in the DBO and that in the LYB. For this purpose, we apply teleseismic tomography to study P-wave velocity structure down to 800km depth beneath east-central China. A modified multiple-channel cross-correlation method is used to collect 28,805 high-quality P-wave arrival-time data from seismograms of distant earthquakes recorded by permanent seismic stations and our temporary stations in the study region. To remove the influence of crustal heterogeneity on the mantle tomography, we used the CRUST1.0 model to correct the teleseismic relative residuals. Our tomography revealed distinct high-velocity (high-V) anomalies beneath the DBO and two flanks of the LYB, and low-velocity (low-V) anomalies above the high-V zones. Combining our tomographic images with previous geological, geochemical and geophysical results, we infer that these high-V and low-V anomalies reflect the detached lithosphere and upwelling asthenospheric materials, respectively, which are associated with the Late Mesozoic dynamic process and the Cretaceous magmatism. We propose a double-slab subduction model that a ridge subduction yielded the adakitic rocks in the LYB during 150–135Ma and the subsequent Pacific Plate subduction played a crucial role in not only the formation of igneous rocks in the LYB but also remelting of the subducted South China Block beneath the DBO during 135–101Ma.
•High-resolution tomograms reveal upper-mantle structure of east-central China.•Upper-mantle velocity anomalies reflect the Cretaceous magmatism.•A double-slab subduction model is proposed to explain all the results.
•Deep earthquakes are relocated precisely using both Chinese and Japanese stations.•Differential travel-time residuals are used to study the fine slab structure.•A metastable olivine wedge (MOW) does ...exist within the Pacific slab.•P-wave velocity of the MOW is 7–9% lower than that of the iasp91 model.
Seismic tomography and numerical simulations show that the western Pacific slab bends horizontally when it reaches the boundary between the upper mantle and lower mantle beneath northeast Asia. It is expected that a metastable olivine wedge (MOW) exists in the cold core of the slab because of a delayed phase transition from olivine to its high-pressure polymorphs. However, it is still debated whether the MOW actually exists or not, and even if it exists, its physical properties, such as seismic velocity and density, are still unclear. In this work we use high-quality arrival-time data of 17 deep earthquakes occurring within the Pacific slab under northeast Asia to study the detailed structure of the slab. The deep earthquakes are relocated precisely by applying a modified double-difference location method to arrival-time data recorded at both Chinese and Japanese stations. Based on the precise hypocentral locations, a forward modeling method and differential travel-time residuals data are used to estimate seismic velocity within the deep source zone, which can decrease or remove the influence of ambient velocity heterogeneities. Our results show that the MOW does exist within the Pacific slab under northeast Asia, and the MOW has a mean velocity anomaly of 7–9% lower than the iasp91 Earth model. The existence of MOW in the slab has important geodynamic implications. It can reduce the speed of slab subduction and affect the generation of deep earthquakes.
The South China block (SCB) is located at the southeastern margin of the Eurasian plate, where intense Mesozoic magmatism and metallogenic belts occurred. The mechanism of mineralization is still ...unclear and debated. To clarify this issue, we determine a robust 3-D model of P-wave tomography of the upper mantle beneath the SCB by using 77,969 high-quality travel-time data of 934 teleseismic events recorded at 315 permanent and 72 portable stations in the SCB. Our results show that high-velocity (high-V) zones exist in the upper mantle under the Yangtze block and in the mantle transition zone under the eastern segment of the Jiangnan orogen. The former reflects thicker cratonic lithosphere, whereas the latter may reflect the deeply subducted paleo-Pacific plate. Low-velocity (low-V) anomalies are revealed in the upper mantle beneath the Cathaysia block, which are located above the high-V anomaly in the mantle transition zone. These low-V anomalies may reflect hot upwelling flows in the upper mantle, which might be related to the large-scale magmatic activities in the late Mesozoic. Our results suggest that the low-V hot mantle materials beneath the Cathaysia block have risen to the shallow lithosphere along magmatic channels such as fault zones, which eroded the nearby cratonic root of the Yangtze block and the overlying lithosphere and destroyed the lithosphere beneath the eastern SCB. The hot upwelling materials mineralized in the shallow part and so formed many metallogenic belts in the SCB.
•The 3-D upper-mantle structure under the South China block (SCB) is studied using teleseismic tomography.•The Yangtze and Cathaysia blocks exhibit higher and lower P-wave velocities, respectively.•Hot mantle upwelling under the Cathaysia block caused lithospheric thinning and rich metallogenic belts in the eastern SCB.
A mineralization zone exists in the Middle and Lower Yangtze River (MLYR) region. Previous studies have shown that this zone might be caused by the rich ejection of magma in the Mesozoic. We have ...applied the teleseismic tomography method to determine a 3-D P-wave velocity structure of the mantle down to 500km depth beneath this region by using 14,740 P-wave arrival times collected from 519 teleseismic events recorded by 46 portable and 47 static seismic stations located in this region. The relative residual times used for the tomography are calculated by the modified multi-channel cross-correlation method which increases not only the efficiency but also the data precisions up to 0.01s. The grid space is set as 1°×1° horizontally and 50–100km vertically. Our tomographic results show that the lithosphere with high velocity anomalies is separated into two parts: one locates above the depth of 100km and the other at the depths between 250km and 400km, and the asthenosphere with low velocity anomalies locates between these two parts of lithosphere, which indicates that the lithosphere delaminated together with the asthenosphere upwelling. The detachment of lithosphere might relate to the subduction of the western Pacific slab. Therefore, our study provides clear evidence to geoscientists for understanding the deep dynamic process beneath this region and a three-stage geodynamic process is developed based on the new evidence.
•The Middle-Lower Yangtze River is an important mineralization zone in China.•A 3-D velocity model down to 500 km deep is inverted by the teleseismic tomography.•The detachment of lithosphere and the upwelling of asthenosphere are clearly shown.•The three-stage geodynamic process is developed according to our results.
SUMMARY
We examine seismic anisotropy beneath eastern China by analysing shear wave splitting of teleseismic SKS, SKKS and PKS phases recorded at 402 permanent and temporary stations. In general, our ...fast directions are approximately oriented in the E–W direction. The delay times vary greatly between 0.5 and 1.9 s. The delay times at stations in the Sichuan basin are less than 0.8 s, which could explain the fossilized anisotropy in the lithospheric mantle and little deformation after the formation of stable block. The fast directions in the Qinling–Dabie orogenic belts orient NWW–SEE, E–W and NEE–SWW, and are roughly parallel to the strikes of orogens that may indicate that the anisotropy contribution comes mainly from the lithospheric mantle. The fast directions mostly oriented in the nearly E–W direction, are generally subparallel to the absolute plate motion directions beneath the North China Craton and South China Block, suggesting it is primarily related to drag induced by the asthenospheric flow.
In this study, we conduct ambient noise tomography and teleseismic two-plane-wave tomography to probe the crustal and uppermost mantle structures in the Middle–Lower Yangtze River region. The data ...used include 14 months (from July 2012 to August 2013) of continuous vertical component ambient noise data and 219 teleseismic earthquakes recorded at 138 broadband seismic stations from Chinese provincial networks and 19 temporary seismic stations deployed by China University of Geosciences (Beijing). First, we apply ambient noise tomography to the collected ambient noise data to generate Rayleigh wave group and phase velocity maps at 5–42 s periods and two-plane-wave tomography method to earthquake data to generate intermediate-to-long period phase velocity maps at 20–143 s periods. We then combine the short-to-intermediate period velocity maps from ambient noise and the intermediate-to-long period phase velocity maps from earthquake data to generate broadband phase velocity maps at periods from 5 to 143 s. By inverting these 5–143 s Rayleigh wave velocity maps, we construct a 3-D shear wave velocity model from the surface to ∼250 km depth in the Middle–Lower Yangtze River region. The 3-D model shows that in the upper crust, the basin regions, including the JiangHan, HeHuai, SuBei, HeFei and NanYang basins, are all featured with low velocities, and the mountain regions with high velocities. In the uppermost mantle, a low-velocity zone at ∼100–200 km depth is observed beneath the Middle–Lower Yangtze River Metallogenic Belt. Moreover, our tomographic results show that the NingWu and NingZhen ore districts are clearly characterized by the strongest low velocity anomaly in the uppermost mantle at ∼70–200 km depth. The depth extent of the low-velocity zone becomes shallower and the amplitude of low velocity anomaly becomes larger from the southwest JiuRui ore district to northeast NingWu ore districts. The change pattern of the low-velocity zone in the depth extent and the amplitude is consistent with the fact that peak ages of magmatic events along the Middle–Lower Yangtze River Metallogenic Belt progressively become younger and younger from 148 Ma in the southwest to 125 Ma in the northeast. The observed low-velocity zone may represent the cooling hot upper mantle which was partially molten in the past resulting from partial melting of the paleo-Pacific plate or of an enriched mantle source induced by the westward subduction of the paleo-Pacific plate. The upwelling of the mantle-derived magmas may result in the formation of these granitic rocks and coeval ores deposits along the Middle–Lower Yangtze River Metallogenic Belt.
•A 3-D Vsv model from surface down to ∼250 km is constructed in the MLYR.•A northeast up-dipping LVZ in the upper mantle is observed beneath the MLYMB.•The observed LVZ is probably the principal area of upper mantle magma reservoir.•The formation of the LVZ may result from the subduction of the paleo-Pacific plate.
We determine a 3-D P-wave velocity structure of the mantle down to 700 km depth under the Kamchatka peninsula using 678 P-wave arrival times collected from digital seismograms of 75 teleseismic ...events recorded by 15 portable seismic stations and 1 permanent station in Kamchatka. The subducting Pacific slab is imaged clearly that is visible in the upper mantle and extends below the 660-km discontinuity under southern Kamchatka, while it shortens toward the north and terminates near the Aleutian–Kamchatka junction. Low-velocity anomalies are visible beneath northern Kamchatka and under the junction, which are interpreted as asthenospheric flow. A gap model without remnant slab fragment is proposed to interpret the main feature of high-V anomalies. Combining our tomographic results with other geological and geophysical evidences, we consider that the slab loss may be induced by the friction with surrounding asthenosphere as the Pacific plate rotated clockwise at about 30 Ma ago, and then it was enlarged by the slab-edge pinch-off by the asthenospheric flow and the presence of Meiji seamounts. As a result, the slab loss and the subducted Meiji seamounts have jointly caused the Pacific plate to subduct under Kamchatka with a lower dip angle near the junction, which made the Sheveluch and Klyuchevskoy volcanoes shift westward.
We conduct a nonlinear joint inversion of receiver functions and surface waves to obtain the lithosphere structure in east‐central China. We also use SKS splitting measurements to evaluate upper ...mantle deformation. The velocity model reveals that, to the east of the North‐South Gravity Lineament, the crust and lithosphere are significantly thinned. Three extensive crustal/lithospheric thinning subregions are identified. This indicates that the lithospheric modification in east‐central China is nonuniform due to heterogeneity of lithospheric strength. Extensive crustal and lithospheric thinning probably occurs in some weak zones such as basin‐range junction belts and large faults. The structure beneath the Dabie orogenic belt is complex due to the collision between the North and South China Blocks during the Late Paleozoic‐Triassic. The Dabie orogenic belt is delineated by a thick crust with a midcrust low‐velocity zone and a two‐directional convergence in the lithospheric scale. The crust and uppermost mantle across the Tanlu fault exhibit a strong seismic velocity contrast, which suggests deep penetration of this lithospheric‐scale fault. Most of our splitting measurements show nearly E‐W trending fast polarization. The similar present‐day lithosphere structure and upper mantle deformation may imply that the eastern North China Craton and South China Block have been dominated by a common dynamic process since the Late Mesozoic. The westward subduction of the Philippine plate and the long‐range effects of the collision between the Indian and Eurasia plates during the Cenozoic may have also contributed to the present velocity structure and stress field of eastern China.
Key Points
A 3‐D S wave model is constructed in east‐central China by a nonlinear joint inversion; three extensive thinning regions are identified
Most of our splitting measurements show consistent nearly E‐W trending fast polarization direction in east‐central China
Similar present structure and deformation imply that eastern NCC and SCB were dominated by a common dynamic process after Late Mesozoic
► We applied a forward-modeling method to study the metastable olivine wedge (MOW). ► We used a modified double-difference method to relocate 78 deep earthquakes. ► The result shows that the MOW with ...a lower velocity does exist in the Pacific slab. ► The deep earthquakes occur within the MOW or along its edges within the slab. ► The transformational faulting may be the mechanism of deep earthquakes.
A metastable olivine wedge (MOW) is detected in the subducting Pacific slab under the Japan Sea by applying a forward-modeling approach with 3-D ray tracing to high-quality arrival-time data from 78 well-located deep earthquakes. The data were recorded by the dense and high-quality seismic networks on the Japan Islands. The double-difference earthquake location technique is improved and used to relocate the 78 deep earthquakes precisely. Our results show that the MOW does exist in the Pacific slab and it has a
P-wave velocity 3% lower than the normal mantle or 4% lower than the surrounding slab velocity. The top and bottom depths of the MOW are 400 and 570
km, respectively, and the MOW is located in the central portion of the slab. After precise relocation, all the 78 deep earthquakes are found to occur within the MOW or along its edges within the slab. The cut-off depth of deep seismicity under the Japan Sea is consistent with the estimated MOW bottom depth. Our results favor the transformational faulting as the mechanism of deep earthquakes in the Pacific slab under the Japan Sea.
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