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First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

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Chinese Physics B 2015年第12期24卷 517-525页

作者：刘雷吕超甲庄春强易丽刘红杜建国 Key Laboratory of earthquake prediction Institute of Earthquake ScienceChina Earthquake Administration institute of Microstructure and Properties of Advanced Materials Beijing University of Technology

The crystal structure and Raman spectra of quartz are calculated by using first-principles method in a pressure range from 0 to 5 GPa. The results show that the lattice constants（a, c, and V） decrease with increasing pressure and the a-axis is more compressible than the c axis. The Si–O bond distance decreases with increasing pressure, which is in contrast to experimental results reported by Hazen et al. [Hazen R M, Finger L W, Hemley R J and Mao H K 1989 Solid State Communications 725 507–511], and Glinnemann et al. [Glinnemann J, King H E Jr, Schulz H, Hahn T, La Placa S J and Dacol F 1992 Z. Kristallogr. 198 177–212]. The most striking changes are of inter-tetrahedral O–O distances and Si–O–Si angles. The volume of the SiO4^4- tetrahedron decreased by 0.9%（from 0 to 5 GPa）, which suggests that it is relatively *** models of the quartz modes are identified by visualizing the associated atomic motions. Raman vibrations are mainly controlled by the deformation of the Si O4-4tetrahedron and the changes in the Si–O–Si bonds. Vibrational directions and intensities of atoms in all Raman modes just show little deviations when pressure increases from 0 to 5 *** pressure derivatives（dνi/d P） of the 12 Raman frequencies are obtained at 0 GPa–5 GPa. The calculated results show that first-principles methods can well describe the high-pressure structural properties and Raman spectra of quartz. The combination of first-principles simulations of the Raman frequencies of minerals and Raman spectroscopy experiments is a useful tool for exploring the stress conditions within the Earth.

关键词： structural properties Raman mode quartz first principles

Anisotropic zoning in the upper crust of the Tianshan Tectonic Belt

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Science China Earth Sciences 2021年第4期64卷 651-666页

作者： Jin LI Yuan GAO Qiong WANG earthquake Administration of Xinjiang Uygur Autonomous Region Urumqi 830011China Key Laboratory of earthquake prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing 100036China

The Tianshan Tectonic Belt is an intracontinental orogenic belt formed by continental convergence that has undergone long-term tectonic evolution. The reactivation that began during the Cenozoic Period has led to complex structural changes. The goals of this study are to review the seismic observational data obtained during 2009–2019 in the Xinjiang regional seismic network and analyze the anisotropy of the upper crust in the Tianshan area. Therefore, a shear-wave splitting system was adopted to collect and analyze shear-wave splitting parameters of 33 stations in the study area. The anisotropy of the upper crust of the Tianshan is spatially diverse, and the dominant polarization directions of fast shear-wave reflect the spatial variations of regional tectonic stress. In addition, the time delays of slow waves are proportional to the intensities of anisotropy in the upper crustal medium. The dominant polarization direction of the fast waves in the western segment of the North Tianshan Mountain,northwestern corner of the Tarim Basin, and northeastern edge of Pamir is consistent with the tectonic stress fields in the area. In the northern part of the Keping Block, the dominant polarization directions of the fast waves are consistent with the fault trends;however, they are at a high angle to the dominant directions of the regional tectonic stress field indicating that the anisotropy is affected by the faults in the area. The anisotropy of the eastern segment of the South Tianshan Mountains and the surrounding area of Urumqi are affected by the local stress field and fault structure. The polarization directions at some of the stations are subparallel to the directions of the regional principal stress. However, for other stations, the polarization directions are aligned with the neighboring faults. The polarization directions of the fast waves in most of the study area are consistent with the local tectonic stress fields. Thus, stress compression phenomena such as the Ta

关键词： Tianshan Tectonic Belt Seismic anisotropy Shear-wave splitting Tectonic stress

Gravity pattern in southeast margin of Tibetan Plateau and its implications to tectonics and large earthquakes

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Earth and Planetary Physics 2019年第5期3卷 425-434页

作者： Yue Wu Yuan Gao Key Laboratory of earthquake prediction Institute of Earthquake ForecastingChina Earthquake Administration

There are many active faults in the southeast margin of Tibetan Plateau,where three large active faults zones,the Longmenshan,Xianshuihe and Anninghe,merge to form a"Y"*** crustal deformation and a complicated fault distribution accompany strong earthquake activity in this *** this paper,we investigate a multi-scale gravity anomaly in the southeastern margin of the Tibetan Plateau using the wavelet transform;we find that the pattern of the gravity field is closely related to the fault system in the study *** the characteristics of this Bouguer gravity anomaly at different orders indicates that the eastern Himalayan syntaxis has produced a strong eastward push during its northward movement,resulting in a shortening of the crust from west to east and a rapid uplift of the Tibetan *** Songpan–Garzêand Sichuan–Yunnan blocks have been forced to slip and extrude southward and eastward *** distributions of seven large earthquakes from 1970 to 2018 reflects the relationship between large earthquakes and characteristics of the gravity *** the tectonic backgrounds of several earthquakes reveals that the large earthquakes occur usually in the high gravity anomaly gradient zone,which corresponds in general to the boundary zones of the *** infer that large earthquakes occur primarily in high Bouguer gravity anomaly zones in the upper crust,while low Bouguer gravity anomalies encompass the lower crust and the uppermost mantle.

关键词： southeast margin of Tibetan Plateau Bouguer gravity anomaly(BA) wavelet transform(WT)and multiscale analysis(MA) focal mechanism of earthquake gradient zone

Deep tectonics and seismogenic mechanisms of the seismic source zone of the Jishishan M_(s)6.2 earthquake on December 18,2023,at the northeast margin of the Tibetan Plateau

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Earth and Planetary Physics 2024年第3期8卷 514-521页

作者： Qiong Wang ShuYu Li XinYi Li Yue Wu PanPan Zhao Yuan Gao Key Laboratory of earthquake prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing 100036China institute of Geophysics China Earthquake AdministrationBeijing 100081China

On December 18,2023,an M_(s)6.2 earthquake occurred in Jishishan,Gansu Province,*** earthquake happened in the eastern region of the Qilian Orogenic Belt,which is situated at the forefront of the NE margin of the Tibetan Plateau(i.e.,Qinghai-Tibet Plateau),encompassing a rhombic-shaped area that intersects the Qilian-Qaidam Basin,Alxa Block,Ordos Block,and South China *** this study,we analyzed the deep tectonic pattern of the Jishishan earthquake by incorporating data on the crustal thickness,velocity structure,global navigation satellite system(GNSS)strain field,and *** discovered that the location of the earthquake was related to changes in the crustal *** results showed that the Jishishan M_(s)6.2 earthquake occurred in a unique position,with rapid changes in the crustal thickness,Vp/Vs,phase velocity,and S-wave *** epicenter of the earthquake was situated at the transition zone between high and low velocities and was in proximity to a low-velocity ***,the source area is flanked by two high-velocity anomalies from the east and *** principal compressive strain orientation near the Lajishan Fault is primarily in the NNE and NE directions,which align with the principal compressive stress direction in this *** some areas of the Lajishan Fault,the principal compressive strain orientations show the NNW direction,consistent with the direction of the upper crustal fast-wave polarization from local earthquakes and the phase velocity azimuthal *** features underscore the relationship between the occurrence of the Jishishan M_(s)6.2 earthquake and the deep inhomogeneous structure and deep tectonic *** NE margin of the Tibetan Plateau was thickened by crustal extension in the process of northeastward expansion,and the middle and lower crustal materials underwent structural deformation and may have been filled with salt-containing fluids during the extension *** presence

关键词： Jishishan M_(s)6.2 earthquake crustal structure anisotropy stress and strain seismogenic mechanism northeast margin of the Tibetan Plateau

An overview on shallow strong earthquake activity and earthquake live losses of Chinese mainland in the centenary from 1901 to 2001

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Acta Seismologica Sinica(English Edition) 2005年第4期18卷 392-401页

作者：傅征祥刘桂萍邵辉成丁香 institute of earthquake Science China Earthquake Administration Beijing 100036 China Department of earthquake Monitoring and prediction China Earthquake Administration Beijing 100036 China earthquake Administration of Shaanxi Province

This paper reviews and analyses briefly the general characteristics of shallow strong earthquakes (MS≥6.0, focal depth h≤70 km) in space, time and magnitude and earthquake fatalities of Chinese mainland in the centenary from 1901 to 2001. During the period from 1901 to 2001, there occurred about 420 strong shallow earthquakes with magnitude MS≥6.0, 88% of them occurred in the western part of the Chinese mainland, which might be related to the strong deformation and motion of the active blocks in the western part. The average focal depth (25 km) in the western part is deeper than that (16 km) in the eastern part, which might be related to obviously thicker crust in the western part. The inhomogeneous distribution of focal depths with the depth profile is related to the variation of frictional and rheologic characteristics with depth in the crust. The shallow strong earthquake activity of Chinese mainland shows a tempo-spatial clustering process. The relation between earthquake magnitude MS and cumulative frequency Nc is lgNc=8.64–0.99MS. About 600 000 people died in the earthquakes of Chinese mainland from 1901 to 2001, the most serious earthquake live losses occurred in Hebei Province (250 723 people died) and Ningxia Hui Autonomous Region (246 269 died). There is no a statistically linear relationship between earthquake live losses and magnitudes. The statistical relationship between the earthquake deaths D and cumulative frequency Nc is lgNc=2.40–0.39lgD, which shows a fractal distribution.

关键词： Chinese mainland shallow earthquake activity live losses 1901~2001

Crustal thicknesses and Poisson's ratios beneath the Chuxiong-Simao Basin in the Southeast Margin of the Tibetan Plateau

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Earth and Planetary Physics 2019年第1期3卷 69-84页

作者： ZiQi Zhang Yuan Gao Key Laboratory of earthquake prediction Institute of Earthquake ForecastingChina Earthquake Administration institute of earthquake Forecasting China Earthquake Administration

In the Southeast Margin of the Tibetan Plateau, low-velocity sedimentary layers that would significantly affect the accuracy of the H-κ stacking of receiver functions are widely *** this study, we use teleseismic waveform data of 475 events from 97 temporary broadband seismometers deployed by ChinArray Phase I to obtain crustal thicknesses and Poisson's ratios within the Chuxiong-Simao Basin and adjacent area, employing an improved method in which the receiver functions are processed through a resonance-removal filter, and the H-κ stacking is *** show that the crustal thickness ranges from 30 to 55 km in the study area, reaching its thickest value in the northwest and thinning toward southwest, southeast and *** apparent variation of crustal thickness around the Red River Fault supports the view of southeastern escape of the Tibetan *** thin crustal thickness in the zone between Chuxiong City and the Red River Fault indicates possible uplift of mantle in this *** positive correlation between crustal thickness and Poisson's ratio is likely to be related to lower crust *** of results obtained from different methods shows that the improved method used in our study can effectively remove the reverberation effect of sedimentary layers.

关键词： receiver functions sedimentary layer southeast margin of the Tibetan Plateau crustal thickness Poisson's ratio Chuxiong-Simao Basin

Adsorption behavior of CO_(2) in magnesite micro-pores at high temperature and pressure

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Geoscience Frontiers 2021年第2期12卷 991-999页

作者： Longxing Yang Lei Liu Hong Liu Li Yi Xiaoyu Gu Haibo Liu Hanyu Wang United Laboratory of High-Pressure Physics and earthquake Science Key Laboratory of Earthquake PredictionInstitute of Earthquake ForecastingCEABeijing100036China

The fluid inclusions in mantle rocks and melt indicated that a large amount of CO_(2)fluid exists in the deep earth,which is of great significance for understanding the deep carbon cycle and the composition of ***,it was also suggested that carbonate minerals were likely to be the main host of mantle *** the same time,the distribution and behavior of carbon in the mantle still remain a *** this paper,the adsorption behavior and occurrence characteristics of supercritical CO_(2)in magnesite(MgCO3)pores were studied by the Grand Canonical Monte Carlo method(GCMC)under the different conditions of CO_(2)pressures(0–100 MPa),temperatures(350–1500 K)and the pore sizes(7.5–30Å).The simulated results showed that the adsorption of CO_(2)in magnesite was a physical adsorption,which was mainly controlled by the intermolecular *** gas adsorption became more stable when the adsorption site shifted from the high energy site to the low energy site with increasing pressure(P)and decreasing temperature(T)and pore *** the same time,the variations of excess adsorption amounts of CO_(2)in the pores of magnesite(Nexcess)under the different conditions were quantitatively *** was found that the Nexcess decreased with increasing T,but increased with increasing P and pore *** results favor understanding the CO_(2)migration,seismic precursor observations,and heat transfer process in the deep earth.

关键词： CO_(2) Magnesite Adsorption Nexcess GCMC Carbon cycle

Contemporary crustal tectonic movement in the southern Sichuan-Yunnan block based on dense GPS observation data

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Earth and Planetary Physics 2019年第1期3卷 53-61页

作者： HongLin Jin Yuan Gao XiaoNing Su GuangYu Fu Key Laboratory of earthquake prediction China Earthquake Administration institute of earthquake Forecasting China Earthquake Administration

We analyzed 360 permanent and campaign GPS data from 1999 to 2017 in the southern Sichuan-Yunan block, and obtained crustal horizontal deformation in this ***, we derived the strain rate using a multi-scale spherical wavelet *** reveal a complex pattern of tectonic movement in the southern Sichuan-Yunnan *** to the stable Eurasian plate, the maximum rate of the horizontal deformation in the southern Sichuan-Yunnan block is approximately 22 mm/*** Xiaojiang fault shows a significantly lower deformation—a left-lateral strike-slip movement of 9.5 mm/*** Honghe fault clearly shows a complex segmental deformation from the north to *** northern Honghe fault shows 4.3 mm/a right strike-slip with 6.7 mm/a extension; the southern Honghe fault shows 1.9 mm/a right strike-slip with 1.9 mm/a extension; the junction zone in the Honghe and Lijiang–Xiaojinhe faults shows an obvious clockwise-rotation *** strain calculation results reveal that the maximum shear-strain rate in this region reaches 70 nstrain/a, concentrated around the Xiaojiang fault and at the junction of the Honghe and Lijiang–Xiaojinhe *** note that most of the earthquakes with magnitudes of 4 and above that occurred in this region were within the high shear strain-rate zones and the strain rate gradient boundary zone, which indicates that the magnitude of strain accumulation is closely related to the seismic *** of the fast shear-wave polarization direction of the upper-crust with the upper-mantle anisotropy and the direction of the surface principal compressive strain rate obtained from the inversion of the GPS data reveals that the direction of the surface principal compressive strain is basically consistent with the fast shear-wave polarization direction of the upper crust anisotropy, but different from the polarization direction of the upper *** results support the hypothesis that the principal elements of the deformation mecha

关键词： GPS data crustal horizontal deformation extension strike slip strain rate fast shear-wave polarization

Spatio-temporal variation and focal mechanism of the Wenchuan M_S8.0 earthquake sequence

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earthquake Science 2009年第2期22卷 109-117页

作者： Wanzheng Cheng Zhiwei Zhang Xiang Ruan earthquake prediction institute Earthquake Administration of Sichuan Province Chengdu 610041 China

Based on abundant aftershock sequence data of the Wenchuan Ms8.0 earthquake on May 12, 2008, we studied the spatio-temporal variation process and segmentation rupture characteristic. Dense aftershocks distribute along Longmenshan central fault zone of NE direction and form a narrow strip with the length of 325 krn and the depth between several and 40 km. The depth profile （section of NW direction） vertical to the strike of aftershock zone （NE direction） shows anisomerous wedgy distribution characteristic of afiershock concentrated regions; it is related to the force form of the Longmenshan nappe tectonic belt. The stronger aftershocks could be divided into northern segment and southern segment apparently and the focal depths of strong aftershocks in the 50 km area between northern segment and southern segment are shallower. It seems like ＇to be going to rupture＇ segment. We also study focal mechanisms and segmentation of strong aftershocks. The principal compressive stress azimuth of aftershock area is WNW direction and the faulting types of aftershocks at southern and northern segment have the same proportion. Because afiershocks distribute on different secondary faults, their focal mechanisms present complex local tectonic stress field. The faulting of seven strong earthquakes on the Longmenshan central fault is mainly characterized by thrust with the component of right-lateral strike-slip. Meantime six strong aftershocks on the Longmenshan back-range fault and Qingchuan fault present strike-slip faulting. At last we discuss the complex segmentation rupture mechanism of the Wenchuan earthquake.

关键词： Wenchuan earthquake strong aftershock spatio-temporal variation focal mechanism solution