Frictional discharge at fault asperities: Origin of fractal seismo-electromagnetic radiation   总被引：1，自引：0，他引：1  

Jun Muto  Hiroyuki Nagahama  Takashi Miura  Ichiro Arakawa 《Tectonophysics》2007,431(1-4):113

To investigate the relation between the rock friction and the fractal electromagnetic radiation before the main-shock of earthquakes, we conducted a friction experiment simulating the motion of an asperity on a fault plane, and observed photon emissions due to electric discharge by dielectric breakdown of ambient gases from friction contacts between rock minerals. This indicates that frictional discharges (plasma generations) could occur locally at microscopic asperities on fault surfaces. From concepts on the fractal size-distribution and temporal evolution of fault asperities, the frictional discharge occurring at asperities on the fault plane can be one of origins of the fractal electromagnetic radiation (Benioff electromagnetic radiation) prior to earthquakes.  相似文献   

Formation of Distinct Granitic Magma Batches by Partial Melting of Hybrid Lower Crust in the Izu Arc Collision Zone, Central Japan   总被引：1，自引：0，他引：1  

Saito  Satoshi; Arima  Makoto; Nakajima  Takashi; Misawa  Keiji; Kimura  Jun-Ichi 《Journal of Petrology》2007,48(9):1761-1791

The Miocene Kofu Granitic Complex (KGC) occurs in the Izu CollisionZone where the Izu–Bonin–Mariana (IBM) arc has beencolliding with the Honshu arc since the middle Miocene. TheKGC includes rocks ranging in compositions from biotite-bearinggranite (the Shosenkyo and Mizugaki plutons), and hornblende–biotite-bearinggranodiorite, tonalite, quartz-diorite, and granite (the Shiodaira,Sanpo, Hirose and Sasago plutons), to hornblende-bearing tonaliteand trondhjemite (the Ashigawa–Tonogi pluton), indicatingthat it was constructed from multiple intrusions of magma withdifferent bulk chemistry. The Sr-isotopic compositions correctedto sensitive high-resolution ion microprobe (SHRIMP) zirconages (SrI) suggest that the primary magmas of each pluton wereformed by anatexis of mixed lower crustal sources involvingboth juvenile basalt of the IBM arc and Shimanto sedimentaryrocks of the Honshu arc. After the primary magmas had formed,the individual plutons evolved by crystal fractionation processeswithout significant crustal assimilation or additional mantlecontribution. SHRIMP zircon U–Pb ages in the KGC rangefrom 16·8 to 10·6 Ma and overlap the resumptionof magmatic activity in the IBM and Honshu arcs at c. 17 Maand the onset of IBM arc–Honshu arc collision at c. 15Ma. The age of the granite plutons is closely related to theepisodic activity of arc magmatism and distinct granitic magmabatches could be formed by lower crustal anatexis induced byintrusion of underplated mantle-derived arc magmas. Based onpressures determined with the Al-in-hornblende geobarometer,the KGC magmas intruded into the middle crust. Thus, the KGCcould represent an example of the middle-crust layer indicatedthroughout the IBM arc by 6·0–6·5 km/s seismicvelocities. This granitic middle-crust layer acted buoyantlyduring the IBM arc–Honshu arc collision, leading to accretionof buoyant IBM arc middle crust to the Honshu arc. KEY WORDS: arc–arc collision; crustal anatexis; granite; Izu–Bonin–Mariana (IBM) arc; Izu Collision Zone  相似文献   

Geostatistical techniques for incorporating spatial correlation into land use change models     

Ademola K. Braimoh  Takashi Onishi 《International Journal of Applied Earth Observation and Geoinformation》2007,9(4):438-446

Land use modeling requires large amounts of data that are typically spatially correlated. This study applies two geostatistical techniques to account for spatial correlation in residential land use change modeling. In the first approach, we combined generalized linear model (GLM) with indicator kriging to estimate the posterior probability of residential development. In the second approach, generalized linear mixed model (GLMM) was used to simultaneously model spatial correlation and regression fixed effects. Spatial agreement between actual and modeled land use change was higher for the GLM incorporating indicator kriging. The GLMM produced more reliable estimates and could be more useful in analyzing the effects of driving factors of land use change for land use planning.  相似文献   

Non-transparent uppermost mantle in the island-arc region of Japan     

Takashi Iidaka  Takaya Iwasaki  Kazuo Yoshimoto   《Tectonophysics》2006,420(1-2):189

In Japan, the crust and uppermost mantle seismic character is yet unimaged although many refraction surveys have been recorded. The longest seismic profiles are analyzed. A remarkable feature, a long-duration coda wave after the PmP wave (reflected wave at the Moho boundary), is observed on the record sections. Several possible models are considered to explain the long-duration coda wave. The model with many scatterers located in the uppermost mantle explains the observed data well while the undulating Moho and continuous layering models do not account for some aspects of the observed data. The scatterer distributed uppermost mantle is not consistent with that of continental region which is often characterized as transparent. We estimate the scattering coefficient of the uppermost mantle and crust using simulations. The scattering coefficients obtained for upper crust, lower crust, and uppermost mantle are 0.01, 0.02, and 0.025, respectively. The scattering coefficient of the uppermost mantle is slightly larger than that of lower crust, which is characterized as being reflective. The many scatterers in the uppermost mantle might be related to magmatism in Japan. This will be one of the important observations for understanding formation processes of the Moho boundary and uppermost mantle in the island-arc environment.  相似文献   

Effect of the development of notches and tension cracks on instability of limestone coastal cliffs in the Ryukyus, Japan   总被引：1，自引：0，他引：1  

Tetsuya Kogure  Hisashi Aoki  Akira Maekado  Takashi Hirose  Yukinori Matsukura 《Geomorphology》2006,80(3-4):236-244

Notches cut by waves are currently developing at the base of vertical coastal limestone cliffs in Okinawa, Japan. The cliff height varies from 3.0–22.1 m, and the maximum notch depth is 8.8 m. Many rectangular or cubic blocks, which appear to have originated from cliff failures, are found on platforms in front of the cliffs. On the flat top surface of the cliff, tension cracks often run parallel to the cliff face. The vertical face of the cliffs displays small undulations but no sliding striation, suggesting that cliff failures have been caused by toppling rather than by shearing or sliding. We use slope stability analysis to determine the critical condition for toppling failure. Physical and mechanical properties of the cliff material were first obtained from laboratory tests. The results indicate that the strength of limestone shows a scale effect, such that the strength decreases with increasing size of the test specimens. Based on this result, we estimated the strength of a rock mass corresponding to the size of the coastal cliff. Cliff stability was then analyzed using a cantilever beam model. Comparison of the stability analysis and the dimension of fallen blocks indicates that toppling failure is strongly associated with the development of notches and tension cracks.  相似文献   

Multi-Wavelength Observation of the 3n/x3.3 Flare of 28 November 1998     

You  Jianqi  Li  Hui  Fan  Zhongyu  Sakurai  Takashi 《Solar physics》2001,203(1):107-117

The 3N/X3.3 flare of 28 November 1998 was observed in multiple wavelength simultaneously. The available data include H images, spectra in Hei 1083 nm and Caii 854.2 nm from Purple Mountain Observatory (PMO), soft X-ray (SXR) and hard X-ray (HXR) images and flux from Yohkoh. Morphological relationship investigation and spectral analysis of these data show: (1) The sudden brightening at loop top above the active region and the steep increase of SXR flux before flare onset suggest that the corona there had already been heated to some extent in the preflare phase. (2) The scales of the Caii 854.2 nm emission areas are very similar to those of the H line, but the emission profiles look like those of the Caii K line. Most of the Hei 1083 nm emissions exist in the bright H kernels and can last to the decay phase. (3) Flare spectra show that line shift and asymmetry are very common in this flare not only in the impulsive phase but also in the decay phase. The difference in the line shifts or asymmetry between Caii 854.2 nm and Hei 1083 nm, as well as the difference between the line center and wings of Caii 854.2 nm imply the existence of a velocity gradient in the line-of-sight direction. (4) Post-flare loops with very deep absorption (70%) and very-high-velocity red shifts (30–90 km s^–1) were observed in Hei 1083 nm during the decay phase. However, only a slight dip can be found in the Caii 854.2 nm profile.  相似文献   

Rare Earth Elements in Hydrothermally Altered Granitic Rocks in the Ranong and Takua Pa Tin‐Field,Southern Thailand     

Akira Imai  Kotaro Yonezu  Kenzo Sanematsu  Takashi Ikuno  Shingo Ishida  Koichiro Watanabe  Visut Pisutha‐Arnond  Somchai Nakapadungrat  Jarupong Boosayasak 《Resource Geology》2013,63(1):84-98

Geochemical studies were conducted on the hydrothermally altered granitic rocks in the Ranong and Takua Pa tin‐fields in southern Thailand in order to investigate the mode of occurrence of REE (rare earth elements), with emphasis placed on a potential REE resource associated with granitic rocks in the Southeast Asian Tin Belt. The total REE (ΣREE) content of altered granitic rocks ranges from 130 to 350 ppm at Haad Son Paen (which is presently mined for kaolin clay) in the Ranong tin‐field, and that of altered granitic rocks and kaolinite veinlets reaches up to 424 ppm and 872 ppm, respectively, at Nok Hook in the Takua Pa tin‐field. Rare earth elements in the altered granitic rocks and kaolinite veinlets show a relatively flat chondrite‐normalized pattern, thus enriched in heavy REE compared with the original granitic rocks and their weathered crusts. At Nok Hook (Takua Pa), the ΣREE content of kaolinite separated from an altered granitic rock by elutriation is 1313 ppm, a ΣREE amount about four times higher than that of whole‐rock composition of the altered granitic rock. Chondrite‐normalized REE patterns of the elutriated kaolinite and of the altered granite are relatively flat. Sequential extraction experiments suggest that 41 and 85 percent of REE are present as ion exchangeable‐form in the altered granitic rock, and in the kaolinite veinlets, respectively. In addition, more than 90% of REE in the kaolinite veinlets are present as the acid‐soluble state. On the other hand, the ΣREE content of kaolinite veinlets and of the kaolinite concentrated by elutriation from an altered granitic rock at Haad Som Paen (Ranong) is 70 ppm and 75 ppm, respectively, thus enrichment of REE in kaolinite was not confirmed. In addition, by the sequential extraction experiments, 23% and 4% of REE were extracted from the altered granitic rock and the kaolinite veinlets at Haad Som Paen. In the altered granitic rocks at Haad Som Paen, REE are present as refractory phases, and REE in the acid‐soluble states had been leached by hydrothermal fluid.  相似文献   

Comparison of the lethal effect of CO2 and acidification on red sea bream (Pagrus major) during the early developmental stages     

Kikkawa T  Kita J  Ishimatsu A 《Marine pollution bulletin》2004,48(1-2):108-110

To compare the acute toxicity of CO(2)- and HCl-acidified seawater, eggs and larvae of a marine fish, Pagrus major, were exposed to seawater equilibrated with CO(2)-enriched gas mixtures (CO(2)=5% or 10%, O(2)=20.95% balanced with N(2)) or seawater acidified with 1 N HCl at two pH levels (pH 6.2 (=5% CO(2)) and 5.9 (=10% CO(2))) for 6 h (eggs) or 24 h (larvae). Mortalities of eggs were 85.8% (CO(2)) and 3.6% (HCl) at pH 6.2, and 97.4% (CO(2)) and 0.9% (HCl) at pH 5.9, while those of larvae were 61.2% (CO(2)) and 1.6% (HCl) at pH 6.2, and 100% (CO(2)) and 5.0% (HCl) at pH 5.9. Thus, previous research on the effects of acidified seawater on marine organisms, as a substitute for CO(2), has largely underestimated the toxic effects of CO(2).  相似文献   

Decision-theoretic sensitivity analysis for reservoir development under uncertainty using multilevel quasi-Monte Carlo methods     

Takashi Goda  Daisuke Murakami  Kei Tanaka  Kozo Sato 《Computational Geosciences》2018,22(4):1009-1020

At various stages of petroleum reservoir development, we encounter a large degree of geological uncertainty under which a rational decision has to be made. In order to identify which parameter or group of parameters significantly affects the output of a decision model, we investigate decision-theoretic sensitivity analysis and its computational issues in this paper. In particular, we employ the so-called expected value of partial perfect information (EVPPI) as a sensitivity index and apply multilevel Monte Carlo (MLMC) methods to efficient estimation of EVPPI. In a recent paper by Giles and Goda, an antithetic MLMC estimator for EVPPI is proposed and its variance analysis is conducted under some assumptions on a decision model. In this paper, for an improvement on the performance of the MLMC estimator, we incorporate randomized quasi-Monte Carlo methods within the inner sampling, which results in an multilevel quasi-Monte Carlo (MLQMC) estimator. We apply both the antithetic MLMC and MLQMC estimators to a simple waterflooding decision problem under uncertainty on absolute permeability and relative permeability curves. Through numerical experiments, we compare the performances of the MLMC and MLQMC estimators and confirm a significant advantage of the MLQMC estimator.  相似文献   

Petrology and shock history of the first depleted-like poikilitic shergottite Asuka 12325     

Atsushi Takenouchi  Akira Yamaguchi  Takashi Mikouchi  Richard Greenwood  Sojiro Yamazaki 《Meteoritics & planetary science》2023,58(10):1406-1428

Asuka (A) 12325 is the first poikilitic shergottite having a depleted pattern in light rare earth elements (REE). Compared with known poikilitic shergottites, A 12325 has smaller but more abundant pyroxene oikocrysts with remarkable Fe-rich pigeonite rims, indicating that A 12325 cooled relatively faster at a shallower part of the crust. The redox condition (logfO₂ = IW + 0.6-IW + 1.7) and Fe-rich chemical compositions of each mineral in A 12325 are close to enriched shergottites. The intermediate shergottites could not form by a simple mixing between parent magmas of A 12325 and enriched shergottites. Although A 12325 contains various high-pressure minerals such as majorite and ringwoodite, plagioclase is only partly maskelynitized. Therefore, the maximum shock pressure may be within 17–22 GPa. Thermal conduction and ringwoodite growth calculation around a shock vein revealed that the shock dwell time of A 12325 is at least 40 ms. The weaker shock pressure and longer shock dwell time in A 12325 may be attained by an impact event similar to those of nakhlites and Northwest Africa (NWA) 8159. Such a weak shock ejection event may be as common on Mars as a severe shock event recorded in shergottites. Alteration of sulfide observed in A 12325 may imply the presence of magmatic fluid in its reservoir on Mars. A 12325 expands a chemical variety of Martian rocks and has a unique shock history among poikilitic shergottites while A 12325 also implies that poikilitic shergottites are common rocks on Mars regardless of their sources.  相似文献