High Q0 Research Articles

A Pn-wave spectral inversion technique based on trust region reflective algorithm

This paper suggests utilizing the trust region reflective (TRR) algorithm to address the inverse problem related to seismic spectrum analysis of Pn waves. By applying this approach, it becomes feasible to simultaneously deduce the seismic moment, corner frequency, tomographic model of Pn-wave attenuation, and site responses while incorporating appropriate constraints based on prior knowledge to ensure solution accuracy. The efficacy of this method has been validated using synthetic data. Specifically, the recorded Pn waves from four underground explosions in North Korea were employed to evaluate the performance of the proposed technique. The derived seismic moment and corner frequency for these events were found to align with the characteristics of the seismic data, earthquake magnitude calculations, and empirical data. The resulting tomographic model of Pn-wave attenuation revealed a spatial distribution of high and low attenuation, indicating significant lithospheric heterogeneity in northeastern China. Areas with low Q0 and low η, such as the Xialiaohe Basin and southwestern Changbai Mountain, suggest a high-temperature environment in the upper mantle cap layer or the presence of molten substances. Conversely, regions with high Q0 and high η, like the northern Changbai Mountain and the vicinity of the eastern Tanlu Fault Zone, characterized by high Pn-wave velocity and thick crust, indicate minimal modification or destruction in the lithosphere. Furthermore, site responses were determined for 75 seismic stations in northeastern China, with their characteristics preliminarily analyzed and interpreted in conjunction with geological context. The iterative process based on the TRR algorithm for Pn-wave spectral inversion proposed in this study demonstrates robust convergence and enhances the fitting accuracy of the observed spectrum. The inversion outcomes from this spectral technique yielded synthetic Pn-wave spectra that closely matched the observed spectra of the four underground explosions in North Korea across various frequency bands for over 90 % of the stations.

Seismic Coda‐Wave Attenuation Tomography of the Jammu and Kashmir Himalaya

AbstractLateral variation in seismic attenuation of the Jammu and Kashmir Himalaya has been studied from local‐earthquake coda waves using 588 single‐trace measurements and back‐projection tomography of coda quality factor (Qc(f)). Single‐trace measurements are performed for a range of lapse time and coda‐window length, and a final choice of 2ts and 90 s, respectively, have been made based on an unbiased distribution of Q0 as a function of epicentral distance. These choices ensure coda start time beyond transient arrivals and satisfies the assumption of coda‐wave generation through multiple forward‐scattering. From single‐traces we obtain Qc(f) = 231 ± 21f0.93±0.05, with a negative correlation between Q0 and η. Qc(f) tomography are presented as 2D‐anomaly maps computed from Qmean at every f, and as absolute Q0 and η maps. These reveal strong frequency‐dependent lateral variations in attenuation. At f = 3–5 Hz, the central Shiwalik Himalaya, Jammu‐Kishtwar Higher Himalaya, Zanskar Ranges, and eastern Kashmir Valley have ∼10% positive Qc anomaly; and high Q0 (270–300) and low η (0.8–0.85), indicating low absorption of seismic energy. The Kishtwar Window region, the reentrant of the Main Boundary and Main Central thrusts, and the western Kashmir Valley have ∼10% negative Qc anomaly, low‐to‐intermediate Q0 (210–250) and high η (0.9–1.0), revealing strong attenuation at structural heterogeneities. At f = 8–14 Hz, the lateral variation in Qc anomaly between the western Kashmir Himalaya (positive) and eastern Jammu‐Kishtwar Himalaya (negative), possibly arises from the crustal thickness variations and steep‐to‐shallow NE dipping Moho from east‐to‐west.

High power test of the first C-band spherical pulse compressor prototype

Recently, a new C-band (5712 MHz) compact spherical radio frequency (RF) pulse compressor was designed and tested for Shanghai Soft X-ray Free Electron Laser Facility (SXFEL). This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two TE1,1,3 modes and a dual-mode polarized coupler. The peak power multiply factor is 6.1 and average power gain 3.8 in theory. During the high power test, a peak power multiply factor of 5.74 and average power gain of 3.77 was achieved. This paper presents the RF measurement of the C-band spherical pulse compressor and the high power test results.

Magnetite microparticles decorated cellulose sponge as an efficacious filter for improved arsenic(V) removal

This work aims to develop an environmentally benign adsorbent using a facile single step synthesis and investigates its remarkably high efficiency toward adsorbing As(V) ions. A base material as simple as a cellulose sponge used in kitchens is chosen for this purpose, modified by coating with magnetite microparticles and then used as an effective adsorbent for the elimination of As(V) from aqueous solution. Fe3O4 coated cellulose sponge (Fe3O4-CS) is characterized using XRD, FESEM, TGA and VSM techniques. The optimum pH is found to be 7 and the saturation point is reached in 60 min. The best suited kinetic and isotherm model were determined through error analysis functions. The adsorption process behaves under a pseudo-second-order kinetic model with R2 value of 0.996 and follows chemisorption. The Langmuir model clearly describes the adsorption reaction with R2 value of 0.969. The maximum adsorption capacity of the adsorbent (Q0) is found to be 349.9 mg/g, which is substantially higher than those from previous reports. Such an exceptionally high Q0 value is backed by elemental mapping studies. Recyclability studies show the retention of 82% efficiency at the end of 5 cycles. Furthermore, the results obtained from column studies demonstrate the applicability of the sponge as an efficient filter for decontaminating As(V) from water. Thus, the developed material would be a promising candidate for the real-time and large scale applications.

Design, fabrication, and cold-test results of C-band spherical RF pulse compressor prototype

Pulse compressor is a useful and common RF structure for Free Electron Laser and Linear Collider Facilities, which can improve the input power of accelerating structures significantly. In this study, we designed, fabricated and tested a prototype of a compact C-band spherical pulse compressor. This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two degenerated TE1,1,3 modes and a dual-mode polarized coupler. The cavity and coupler were designed and machined separately and then brazed together. The prototype was tested carefully using vector network analyzer, and a cold-test system was set up to check the working conditions of the spherical pulse compressor with inversed input power Associated with the C-band high-gradient accelerating structures, the peak power gain and energy multiply factor can be as high as 6.1 and 1.85, respectively, in theory. The average power gain is 3.8 in the first 0.372 μs after the phase reverse, which is the accelerator filling time. During the cold test, a peak power multiply factor of 6.04 and an energy multiply factor of 1.83 were achieved. The test results agreed with the design well. The prototype was successfully made as a pre-research for the future energy multiplying scheme of SXFEL.

Seismic Attenuation of the Eastern Himalayan and Indo‐Burman Plate Boundary Systems, Northeast India

AbstractWe use local earthquake coda waveform to characterize the seismic attenuation across northeast India. We measure temporal decay of coda amplitude to estimate coda quality factor (Qc) at frequencies 1 to 14 Hz and abstract Q0 and its frequency dependence (η). Single‐trace measurements reveal similar average Qc between 1 and 3 Hz and significant variation at higher frequencies. We combine single‐trace Qc measurements into a backprojection algorithm to compute 2‐D Qc tomography maps. The Qc maps reveal strong correlation with tectonic settings. At low frequencies (1–5 Hz) we observe relatively lower Qc in the Sikkim and Eastern Himalaya, southern Tibetan Plateau, and Bengal Basin, while the intraplate region and Indo‐Burman subduction zone have higher Qc. At higher frequencies (>5 Hz) we observe pronounced low Qc beneath Sikkim Himalaya, relatively lower Qc in the intraplate region and relatively higher Qc in the Bengal Basin and Indo‐Burman subduction zone. We compare our Q0 map with Vs tomography to characterize the crust. The lateral variation in the structure of the Himalayan thrust sheets between Sikkim and Eastern Himalaya is highlighted by low and intermediate Q0, respectively. The southern Tibetan Plateau, known to have low Vs due to elevated crustal temperatures, is characterized by low Q0, indicating associated scattering and anelastic effects. The intraplate continental crust and the cold elastic subducting oceanic lithosphere have intermediate‐to‐high Vs and are marked by high Q0. The Bengal Basin, with thick low Vs sedimentary layers overlying a rift‐faulted high Vs transitional crust, has low‐to‐intermediate Q0 due to depth averaging of attenuation characteristics.

RF design of a C-band compact spherical RF pulse compressor for SXFEL

A new C-band (5712MHz) compact spherical radio frequency (RF) pulse compressor was designed for the Soft X-ray Free Electron Laser facility (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). Using only one high Q0 spherical RF resonant cavity which works on two TE113 modes and a dual-mode polarized coupler, this pulse compressor could achieve an average power gain of 3.8. Associated with the C-band accelerator, an energy gain of 1.85 with the coupling coefficient of 4.9 could be achieved. Particularly it could make the output power stable. This paper presents the scheme of the C-band spherical pulse compressor, as well as the RF design and details of the frequency sensitivities and machining considerations.

Study of the effect of NbN on microwave Niobium cavities for gravitational wave detectors

Superconducting reentrant cavities may be used in parametric transducers for resonant-mass gravitational wave detectors. When coupled to a spherical resonant antenna, transducers will monitor its mechanical quadrupolar modes, working as a mass-spring system. In this paper we will investigate the effect of the Niobium Nitride (NbN), produced through plasma immersion ion implantation (PIII), on the quality factor of reentrant Niobium (Nb) cavities. With the PIII surface treatment unloaded electrical Q-factors (Q0) of the order of 105 were obtained in cryogenic conditions. These results indicated a significant increase in the effect of superconductivity after the cavity surfaces have been heavily attacked by a concentrated acid mixture and after suffering successive PIII processes. Q0's ∼ 3.0 × 105 at 4.2 K are expected to be obtained using Nb RRR399 with a suitable surface treatment. These cavities, with high Q0, are already installed and being tested in the Gravitational Wave Detector Mario Schenberg. The experimental tests have been carried out at the laboratories of the National Institute for Space Research (INPE).

Impact of nitrogen doping of niobium superconducting cavities on the sensitivity of surface resistance to trapped magnetic flux

Future particle accelerators such as the SLAC “Linac Coherent Light Source-II” (LCLS-II) and the proposed Cornell Energy Recovery Linac require hundreds of superconducting radio-frequency (SRF) niobium cavities operating in continuous wave mode. In order to achieve economic feasibility of projects such as these, the cavities must achieve a very high intrinsic quality factor (Q0) to keep cryogenic losses within feasible limits. To reach these high Q0's in the case of LCLS-II, nitrogen-doping of niobium cavities has been selected as the cavity preparation technique. When dealing with Q0's greater than 1 × 1010, the effects of ambient magnetic field on Q0 become significant. Here, we show that the sensitivity to RF losses from trapped magnetic field in a cavity's walls is strongly dependent on the cavity preparation. Specifically, standard electropolished and 120 °C baked cavities show a sensitivity of residual resistance from trapped magnetic flux of ∼0.6 and ∼0.8 nΩ/mG trapped, respectively, while nitrogen-doped cavities show a higher sensitivity of residual resistance from trapped magnetic flux of ∼1 to 5 nΩ/mG trapped. We show that this difference in sensitivities is directly related to the mean free path of the RF surface layer of the niobium: shorter mean free paths lead to less sensitivity of residual resistance to trapped magnetic flux in the dirty limit (ℓ ≪ ξ0), while longer mean free paths lead to lower sensitivity of residual resistance to trapped magnetic flux in the clean limit (ℓ ≫ ξ0). These experimental results are also shown to have good agreement with recent theoretical predictions for pinned vortex lines oscillating in RF fields.

Mesoporous titania spheres derived from sodium alginate-gum acacia composite beads: Efficient adsorbent for “Reactive blue H5G” dye

Dye sorbing mesoporous titania spheres (TS) are being reported in the present communication. TS were fabricated by polymerizing titanium (IV) isopropoxide under the templating and structure directing influence of sodium alginate-gum acacia composite beads. The TS synthesis was optimized by varying the reaction parameters while targeting the removal of reactive blue H5G dye from aqueous solutions, which was chosen as model reactive azo dye for the study. The optimum performance TS (TSAA11) sample has been extensively characterized using Fourier transform infrared spectroscopy, X-ray diffraction study, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. Under the optimized conditions TSAA11 was capable of capturing 92% dye from 100mg/l dye solution. The adsorption equilibrium data indicated that the TSAA11 has high Q0 (100)mg/g and heterogeneous surface sites for the adsorption. A linear plot of t/(qt) vs. t indicated that the dye sorption followed pseudo-second-order kinetics which supported chemisorption. The rate constants at 100, 150, 200mg/l initial dye concentrations were 1.48×10−3, 2.65×10−3, and 10.6×10−2g/mgmin respectively. The used TSAA11 was recovered with 1M NaOH and used for three consecutive cycles where it was possible to remove 87% dye even in the third cycle. Photocatalytic study indicated that TSAA11 is capable of degrading 86% dye from 100mg/l dye solution under the exposure to sunlight for 5h. This study indicates that TSAA11 may be utilized as promising adsorbent for reactive anionic azo dyes.

Electrospray droplet exposure to polar vapors: delayed desolvation of protein complexes.

Fragile non-covalent complexes are susceptible to dissociation upon introduction into and transmission through the mass spectrometer. The exposure of nanoelectrospray droplets to various polar vapors, which are introduced into the curtain gas, is shown to stabilize non-covalent protein complexes even under relatively energetic ion transfer conditions. This study probes the mechanism by which polar vapor exposure appears to stabilize non-covalent protein complex ions in the gas phase. Holomyoglobin and hemoglobin were dissolved in either aqueous 1 mM ammonium acetate or ammonium bicarbonate solutions and ionized via nanoelectrospray ionization in the positive polarity. Polar vapors were entrained within the counter-current drying gas and exposed to nanoelectrospray droplets for circa 1 ms within the interface of a quadrupole/time-of-flight mass spectrometer. Mass spectra were acquired using various voltage gradients within the mass spectrometer. In the absence of added reagent vapors, significant fragmentation of holomyoglobin ions is noted with high voltage gradients for ions either entering or departing q0, a transmission quadrupole closely coupled to the skimmer exit. However, upon the introduction of reagent vapors, essentially 100% of the holomyoglobin complex can be preserved. Significant stabilization is noted at both relatively high q0 entrance and exit gradients when ions are transmitted through q0. These results indicate that upon vapor exposure the holomyoglobin ions are not completely desolvated as they enter or exit q0 under normal ion transmission conditions. The apparent stabilization of protein complexes and other non-covalent complexes noted here and elsewhere is attributed to the delayed desolvation of the ions. This allows the solvated ions to be transmitted through relatively high voltage gradients without disrupting the non-covalent interactions holding the complexes together.

Proof-of-principle demonstration of Nb3Sn superconducting radiofrequency cavities for high Q applications

Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb3Sn. In this paper, we present results for single cell cavities coated with Nb3Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q0 out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q0 at quench of 8 × 109. In each case, the peak surface magnetic field at quench was well above Hc1, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q0 values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb3Sn cavities in future applications.

Lg attenuation in the central and eastern United States as revealed by the EarthScope Transportable Array

Lg waveforms recorded by EarthScope's Transportable Array (TA) are used to estimate Lg Q0 in the central and eastern United States (CEUS). Attenuation is calculated based on Lg spectral amplitudes filtered at a narrow band from 0.5 to 1.5 Hz. Two-station and reverse two-station techniques are used to calculate Q0 values. 39 events occurring from 2010 to 2012 and ranging from magnitude 3 to magnitude 6 are used in this study. 39,258 and 4,627 interstation Q0 values are determined using the two-station and reverse two-station techniques, respectively. The results show northeast trending high Q0 regions (low attenuation) ranging from eastern New Mexico to Wisconsin. Regions of low Q0 (high attenuation) are seen along the Minnesota–Wisconsin border, the Gulf Coastal Plain (GCP), along the South Dakota–Nebraska border, and along the Oklahoma–Texas border. A positive correlation between heat flow, sediment thickness, recent tectonic activity, fluids, and low Q0 was observed. Areas with low heat flow, thin sediment cover, no recent tectonic activity, and a lack of fluids were observed to have consistently high Q0. These new models use a greater amount of data, attain more coverage than previous studies, and better constrain attenuation. This increase in detail can improve high frequency ground motion predictions of future large earthquakes for more accurate far field hazard assessment and improve the overall understanding of the structure and assemblage of the CEUS.

Determination of the k 0-values for 75Se, 110mAg, 115Cd–115mIn, 131Ba, and 153Sm by irradiation in highly thermalized neutron flux

The k0-values were determined for five high Q0(n,γ) reactions, including 74Se(n,γ) 75Se, 109Ag(n,γ) 110mAg, 114Cd(n,γ) 115Cd–115mIn, 130Ba(n,γ) 131Ba, and 152Sm(n,γ) 153Sm. These determinations were carried out under favorable experiment conditions: the irradiations were performed in a highly thermalized neutron flux, the irradiated target samples were counted at a far distance from HPGe detector with an efficiency carefully calibrated, and the k0-values were calculated against an internal comparator. When compared to the new values from this work, the 2003 recommended 110mAg k0-values are confirmed. The other confirmed recommended k0-value is that of 75Se 400.7 keV line. However, for the other 75Se γ-lines, the new k0-values are 4–10 % higher. It is assumed that an inaccurate efficiency calibration was used when the recommended k0-values were measured. For the other three nuclides, the new k0-values are higher by 4 % for the 115Cd–115mIn γ-lines, lower by 6–8 % for the 131Ba γ-lines, and lower by 8.8 % for the 153Sm 103.2 keV γ-line.

Role of river-derived algae on bioaccumulation in fixed bed reactors; a low-cost safe drinking water plant

Abstract River-derived algae, Phormidium luridum, Gloeothece rupestris and Chlorococcum infusionum a lowcost material were studied for its ability to remove water pollutants for safe drinking water at neutral pH. The algae were grown on naturally occurring gravels in a glass column of nutrient enriched with raw-water media. The effect of flow-rate and temperature on bioaccumulation was investigated. Sorption isotherm followed the Langmuir model with a high Q0 value (22.7 mg g−1) and the value is in well agreement with the break through capacity (16.8 mg g−1). Different physicochemical and bacteriological parameters were studied to investigate the purity of the effluent. The method effectively permits the quantitative removal (>95%) of both chemical (F−, AsO4 −3, PO4 −3, Fe+3, As+3) and bio-pollutants (total coli form, Faecal coli form, E. coli), from raw water.

The updated crustal attenuation in North China using ML amplitude tomography

We have updated the lateral variations of the quality factor Q0 (Q at 1 Hz) beneath the crust of North China using ML amplitude tomography with near three times data. The data were selected from the Annual Bulletin of Chinese Earthquakes (ABCE) in 1985–2009, including 26 283 ML amplitude readings from 4 204 events recorded by 38 stations. The result is similar with previous research but has higher resolution. Estimated Q0 values are consistent with tectonic and topographic structure in North China. Q0 is low in the active tectonic regions having many faults, such as Bohai bay, North China basin, the Shanxi and Yinchuan grabens, while it is high in the stable Ordos craton. Q0 values are low in several topographically low-lying areas, such as the North China, Taikang-Hefei, and Subei-Huanghai Sea basins, whereas it is high in mountainous and uplift regions exhibiting surface expressions of crystalline basement rocks: the Yinshan, Yanshan, Taihang, Qinling and Dabie mountains, Luxi and Jiaoliao uplifts. Quality factor estimates are also consistent with Pn and Sn velocity patterns. High velocity values in general correspond with high Q0 and vice versa. This coincides with a common temperature influence in the crust and uppermost mantle.

Seismic Lg‐wave Q tomography in and around Northeast China

We investigate regional variations in the Lg‐wave quality factor (Q) in Northeast China and its vicinity with a tomographic method. Digital seismic data recorded at 20 broadband stations from 125 regional events are used to extract Lg‐wave spectra. Tomographic inversions are independently conducted at 58 discrete frequencies distributed log evenly between 0.05 and 10.0 Hz. We simultaneously invert for the Lg‐wave Q distribution and source spectra at individual frequencies without using any a priori assumption about the frequency dependence of the Q model and source function. The best spatial resolution is approximately 1° × 1° in well‐covered areas for frequencies between 0.4 and 2.0 Hz. The Lg Q shows significant regional variations and an apparent relationship with regional geology. We use a statistical method to investigate the regional variations of Lg Q and their frequency dependence. The average Q0 (1 Hz Lg Q) in the entire investigated region is 414. Sedimentary basins are usually characterized by lower average Q0 values (from 155 to 391), while volcanic mountain areas have relatively high average Q0 values (from 630 to 675). Lg Q generally increases with increasing frequency. However, the frequency dependence has complex nonlinear features on a double‐logarithmic scale, indicating that the commonly adopted power‐law relationship may be oversimplified in a broad frequency band. The frequency dependence varies in different geological areas, with larger variations seen at lower frequencies.

Investigation of the impurity concentrations and product activities of some targets used in radioisotope production: a neutron activation analysis study

Neutron activation analysis using the k0 standardization method (k0-NAA) and fast neutron activation analysis using reactor fission neutrons, were used to determine the impurity concentrations in WO3, MoO3, SnO2 and TeO2 targets. The radioimpurities 124Sb, 134Cs, 60Co, 87Rb, 182Ta, 233Pa, 65Zn, 59Fe, 110mAg, 51Cr, 95Zr, 75Se and 114mIn were found in the irradiated targets and their origin either neutron capture reactions, or threshold reactions or both were identified. The specific activities of 187W, 188Re, 99mTc, 113mIn, 117mSn and 131I radioisotopes were determined. It is shown that the epithermal neutron flux significantly contributes to the isotopes characterized with high Q0 values. It is shown that the 117mSn isotope can be produced with a high specific activity using the fast neutron component of the reactor neutron spectrum.

ML Amplitude Tomography in North China

We have selected 10,899 M L amplitude readings from 1732 events re- corded by 91 stations, as reported in the Annual Bulletin of Chinese Earthquakes (ABCE), and have used tomographic imaging to estimate the lateral variations of the quality factor Q0 (Q at 1 Hz) within the crust of Northern China. Estimated Q0 values vary from 115 to 715 with an average of 415. Q0 values are consistent with tectonic and topographic structure in Eastern China. Q0 is low in the active tectonic regions having many faults, such as the Shanxi and Yinchuan Grabens, Bohai Bay, and Tanlu Fault Zone, and is high in the stable Ordos Craton. Q0 values are low in several topographically low-lying areas, such as the North China, Taikang-Hefei, Jianghan, Subei-Yellow Sea, and Songliao basins, whereas it is high in mountainous and uplift regions exhibiting surface expressions of crystalline basement rocks: the Yinshan, Yanshan, Taihang, Qinlin, Dabie and Wuyi Mountains, and Luxi and Jiaoliao Uplifts. Quality-factor estimates are also consistent with Pn- and Sn-velocity patterns. High- velocity values, in general, correspond with high Q0 and low-velocity values with low Q0. This is consistent with a common temperature influence in the crust and uppermost mantle.

A Study of Lg Coda Attenuation beneath North China: Seismic Imaging of Lg Coda Q0

AbstractBy using 560 Lg coda Q0 values measured on propagating paths, the Q0 image in the crust beneath the North China region is restructured with a stochastic modeling and the singular value decomposition. The result indicates that there is remarkable lateral heterogeneity on Lg coda Q0 distribution in the crust beneath the North China region, similar to the velocity image, and closely related with the known surface geological features: the high Q0 areas exist beneath the Taihang and Yanshan mountains and the Luxi uplift area, and low Q0 values appear below the Jizhong, Huanghua and Jiyang depressions and the plain areas. There is a clear division between the high and low Q0 values. Compared with the heat flow values in North China, most the low Q0 value areas are located in the high heat flow areas. It is possibly related with hot material activity in the crust below these areas. Although there is a clear difference between the high and low Q0 value areas in the crust of North China, as a whole North China belongs to low Q0 value abnormal regions. It means that the region is a high seismic wave attenuation area. Probably it is resulted from the interaction between the Eurasia and Pacific plates, which causes crust thinning and hot material upwelling.