Analysis of stick-slip and earthquake mechanism     

Yoshiaki Ida 《Physics of the Earth and Planetary Interiors》1975,11(2):147-156

A mathematical model of a sliding system that contains a frictional surface embedded in an elastic specimen and machine is proposed to analyze the frictional behavior observed in laboratory and field. It is shown that stick-slip occurs if the slope of the velocity-stress relation on the sliding surface exceeds a critical value at a certain point between static and kinetic frictions. This condition, coupled with Amontons' law and other subsidiary relations, predicts the effects of normal stress, gouge thickness, temperature, and loading rate etc. on the stick-slip instability, consistent with known experimental evidence. The elastic-wave radiation associated with stick-slip is governed by Brune's source time function, in which rise time and effective stress are proportional to fault dimension and stress drop, respectively.  相似文献   

Slow-moving deformation pulses along tectonic faults     

Yoshiaki Ida 《Physics of the Earth and Planetary Interiors》1974,9(4):328-337

A model of slow-moving disturbances of deformation is proposed to interpret the observed propagations of earthquake foci and nonseismic creep. The analysis is based on the assumption that thin fault gouge participates in the viscous slip. Nonuniform deformation diffusses at the rate of ν = μw/2η for the gouge of viscosity η and thickness w that is enclosed by the elastic rocks of rigidity μ. A crack-like solution propagates uniformly, involving the discontinuity that bounds the faulted area by an unfractured part, or by another gouge with different viscosity. The unit of the propagation velocity of such cracks is also given by the above-defined ν. Comparing the expression of ν with the various field observations, most of which yield the propagation speeds of 10–10⁴ km/year, the effective viscosity of the gouge is estimated as 10¹¹–10¹⁴ poises. The nonseismic fault creep in central California is analysed, and a little higher value of acting stress is obtained than the result of Nason and Weertman (1973).  相似文献   

Thermophysical properties of lunar material returned by Apollo missions     

Ki-Iti Horai  Naoyuki Fujii 《Earth, Moon, and Planets》1972,4(3-4):447-475

Data on thermophysical properties measured on lunar material returned by Apollo missions are reviewed. In particular, the effects of temperature and interstitial gaseous pressure on thermal conductivity and diffusivity have been studied. For crystalline rocks, breccias and fines, the thermal conductivity and diffusivity decrease as the interstitial gaseous pressure decreases from 1 atm to 10^–4T. Below 10^–4T, these properties become insensitive to the pressure. At a pressure of 10^–4T or below, the thermal conductivity of fines is more temperature dependent than that of crystalline rocks and breccias. The bulk density also affects the thermal conductivity of the fines. An empirical relationship between thermal conductivity, bulk density and temperature derived from the study of terrestrial material is shown to be consistent with the data on lunar samples. Measurement of specific heat shows that, regardless of the differences in mineral composition, crystalline rocks and fines have almost identical specific heat in the temperature range between 100 and 340K. The thermal parameter calculated from thermal conductivity, density and specific heat shows that the thermal properties estimated by earth-based observations are those characteristic only of lunar fines and not of crystalline rocks and breccias. The rate of radioactive heat generation calculated from the content of K, Th and U in lunar samples indicates that the surface layer of the lunar highland is more heat-producing than the lunar maria. This may suggest fundamental differences between the two regions.Now at Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York, U.S.A.  相似文献   

Detailed horizontal crustal movements associated with the 1923 Kanto earthquake as deduced from network adjustment of old data including the third order triangulation stations     

Yoichiro Fujii   《Journal of Geodynamics》2003,35(4-5):457-469

The crustal movements associated with the 1923 Kanto, Japan, earthquake of magnitude 7.9 are deduced from the results of network adjustments with the pre-seimic and post-seismic geodetic data including up to the third order triangulation. The average spacing of the third triangulation is 4 km of higher density as compared with the first order triangulation and the second order triangulation, so we can expect to find much more detailed behavior of the released crustal strain. The main rupture of the 1923 Kanto earthquake that had occurred in the Sagami Bay has been estimated from the crustal deformations deduced from repetition of the first order triangulation and the second order triangulation, while the detailed deformations associated with the secondary faulting are deduced for the first case from the repeated third order triangulation. We find evidence for the secondary faultings in the south Kanto district, Japan, mainly from the pattern of the released strain with the order of 10⁻⁴ and some of them are associated with the surface breakages. We carefully investigate whether these secondary faultings had originated with fracturing at the depth or not. We cannot find any evidence for deep fracturing, though we find remarkable high earth strain release along some secondary faultings. This is mainly due to the fact that the area of high released strain is very limited and narrow along the direction perpendicular to the faulting.  相似文献   

Response to the comment by R. Stalder on “composition of aqueous fluid coexisting with mantle minerals at high pressure and its bearing on the differentiation of the earth’s mantle”     

Kenji Mibe  Toshitsugu Fujii 《Geochimica et cosmochimica acta》2004,68(4):929-930

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Source mechanism of a large scale gas outburst at Sunagawa Coal Mine in Japan     

K. Sato  Y. Fujii 《Pure and Applied Geophysics》1989,129(3-4):325-343

On January 29ty, 1986, the third largest gas outburst in Japan took place at Sunagawa Coal Mine, which is the only hydraulic mine in Japan. It occurred at a face of a cross-cut, just after a coal seam was outcropped by blasting for drivage of the cross-cut. The site of the gas outburst was located 1,180 m below the surface. No workers were injured, but the cross-cut was plugged with 1,600 m³ of coal fragments extending over 100 m behind the face and 60,000 m³ of methane gas was emitted.The site of the gas outburst was investigated in detail to clarify the geological features. A normal and a reverse fault existed at the site. The area of the ejected zone was about 400 m² and extended upward along the normal fault. The shape of the ejected zone suggests a great role of the normal fault on the gas outburst.Digital seismograms, recorded by a mine-wide seismic array at the coal mine, consisting of 27 microseismic events were used to investigate the gas outburst. Magnitude, seismic energy release, distribution of hypocenter and focal mechanism were analyzed. Taking the shape of the ejected zone together with results of the seismological investigation into consideration, it appears that the seismicity started with left-lateral faulting of the reverse fault and then right-lateral faulting of the normal fault followed. The faulting of the normal fault might be the direct cause and be the predominant mechanism of the gas outburst.Presented at the Fred Leighton Memorial Workshop on Mining Induced Seismicity, Montreal, Canada, August 30, 1987.  相似文献   

Progressive metamorphism of the Taitao ophiolite; evidence for axial and off-axis hydrothermal alterations     

Takazo Shibuya  Tsuyoshi Komiya  Ryo Anma  Tsutomu Ota  Soichi Omori  Yoshiaki Kon  Shinji Yamamoto  Shigenori Maruyama 《Lithos》2007,98(1-4):233-260

We estimated metamorphic conditions for the  6 Ma Taitao ophiolite, associated with the Chile triple junction. The metamorphic grade of the ophiolite, estimated from secondary matrix minerals, changes stratigraphically downwards from the zeolite facies, through the prehnite–actinolite facies, greenschist facies and the greenschist–amphibolite transition, to the amphibolite facies. The metamorphic facies series corresponds to the low-pressure type. The metamorphic zone boundaries are subparallel to the internal lithological boundaries of the ophiolite, indicating that the metamorphism was due to axial hydrothermal alteration at a mid-ocean ridge.

Mineral assemblages and the compositions of veins systematically change from quartz-dominated, through epidote-dominated, to prehnite-dominated with increasing depth. Temperatures estimated from the vein assemblages range from  230 °C in the volcanic unit to  380 °C at the bottom of the gabbro unit, systematically  200 °C lower than estimates from the adjoining matrix minerals. The late development of veins and the systematically lower temperatures suggest that the vein-forming alteration was due to off-axis hydrothermal alteration.

Comparison between the Taitao ophiolite with its mid-ocean ridge (MOR) affinity, and other ophiolites and MOR crusts, suggests that the Taitao ophiolite has many hydrothermal alteration features similar to those of MOR crusts. This is consistent with the tectonic history that the Taitao ophiolite was formed at the South Chile ridge system near the South American continent (Anma, R., Armstrong, R., Danhara, T., Orihashi, Y. and Iwano, H., 2006. Zircon sensitive high mass-resolution ion microprobe U–Pb and fission-track ages for gabbros and sheeted dykes of the Taitao ophiolite, Southern Chile, and their tectonic implications. The Island Arc, 15(1): 130–142).  相似文献   

Thinning of the near-earth (10∼15 R_E) plasma sheet preceding the substorm expansion phase     

A. Nishida  K. Fujii 《Planetary and Space Science》1976,24(9):849-853

The timing of the plasma-sheet thinning relative to the onset of the expansion phase of substorms is examined by the analysis of the OGO 5 electron (79 ± 23 keV) and proton (100～150 keV) data with the aid of simultaneous magnetic field observations. It is found that the timing of the thinning is significantly dependent on the distance. At $\text{x}{}^2\text{+ y}{}^2\text{? 15 R}{}_{\mathrm{E}}$ the thinning often starts before the onset, while at $\text{x}{}^2\text{+ y}{}^2\text{? 15 R}{}_{\mathrm{E}}$ it tends to occur after the onset, where x and y refer to solar magnetospheric coordinates. The thinning that precedes the expansion-phase onset has been found to reduce the thickness to ～1 R_E, and further thinning may occur in a spatially limited region. Hence it is conceivable that the formation of the neutral line characterizing the substorm expansion phase is the consequence of the thinning of the plasma sheet in the near-Earth region.  相似文献   

Correction to: A web-based real-time and full-resolution data visualization for Himawari-8 satellite sensed images     

Ken T. Murata  Praphan Pavarangkoon  Atsushi Higuchi  Koichi Toyoshima  Kazunori Yamamoto  Kazuya Muranaga  Yoshiaki Nagaya  Yasushi Izumikawa  Eizen Kimura  Takamichi Mizuhara 《Earth Science Informatics》2018,11(2):239-240

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A new record of Sebastes koreanus from China based on morphological characters and DNA barcoding     

方亚璐  宋娜  高天翔 《中国海洋湖沼学报》2015,33(3):590-596

A new record of Sebastes koreanus(Kim and Lee,1994) was documented based on morphological characters and DNA barcoding. Fifty-six S ebastes specimens were collected from the coastal waters of northern China. Samples were identified as S. koreanus based on morphological characters. The coloration and morphometric measurements were consistent with those described from specimens collected in South Korea. In this study,specimens had the following morphological characteristics:light brown body with dark stripes and tiny dark spots,4–5 wide indistinct vertical patterns on the side,2 radial stripes behind and below the eyes,1 large dark blotch on the opercle. Additionally,the following meristic characters were recorded:dorsal fin XIV-13,pectoral fin 16,anal fin III-6–7,pelvic fin I-5,lateral line scales 29–30,and vertebrae 26. The fragment of cytochrome oxidase subunit I(C OI) gene of mitochondrial DNA was sequenced for phylogenetic analysis. The mean genetic distance within the species was 0.3%. Net genetic distances between S. koreanus and other S ebastes species ranged from 3.1% to 7.6%,which was greater than the threshold for species delimitation. The phylogenetic analysis strongly supports the validity of S. koreanus in China at the genetic level. The origion,evolution,patterns of speciation and unique features in genome divergence among primate lineages of this species still need future directions of research.  相似文献