On estimating frequency-magnitude relations from heterogeneous catalogs

The paper studies the effect of magnitude errors on heterogeneous catalogs, by applying the apparent magnitude theory (seeTinti andMulargia, 1985a), which proves to be the most natural and rigorous approach to the problem. Heterogeneities in seismic catalogs are due to a number of various sources and affect both instrumental as well as noninstrumental earthquake compilations.The most frequent basis of heterogeneity is certainly that the recent instrumental records are to be combined with the historic and prehistoric event listings to secure a time coverage, considerably longer than the recurrence time of the major earthquakes. Therefore the case which attracts the greatest attention in the present analysis is that of a catalog consisting of a subset of higher quality data, generallyS ₁, spanning the interval T ₁ (the instrumental catalog), and of a second subset of more uncertain magnitude determination, generallyS ₂, covering a vastly longer interval T ₂ (the historic and/or the geologic catalog). The magnitude threshold of the subcatalogS ₁ is supposedly smaller than that ofS ₂, which, as we will see, is one of the major causes of discrepancy between the apparent magnitude and the true magnitude distributions. We will further suppose that true magnitude occurrences conform to theGutenberg-Richter (GR) law, because the assumption simplified the analysis without reducing the relevancy of our findings.The main results are: 1) the apparent occurrence rate exceeds the true occurrence rate from a certain magnitude onward, saym _GR; 2) the apparent occurrence rate shows two distinct GR regimes separated by an intermediate transition region. The offset between the two regimes is the essential outcome ofS ₁ being heterogeneous with respect toS ₂. The most important consequences of this study are that: 1) it provides a basis to infer the parameters of the true magnitude distribution, by correcting the bias deriving from heterogeneous magnitude errors; 2) it demonstrates that the double GR decay, that several authors have taken as the incontestable proof of the failure of the GR law and of the experimental evidence of the characteristic earthquake theory, is instead perfectly consistent with a GR-type seismicity.     

Numerical Modeling of the Ston-Slano (Croatia) Aftershock Sequence

The rate of aftershock occurrence after the M6 Ston-Slano (Croatia) earthquake is modeled as the Epidemic Type Aftershock Sequence (ETAS). Increase of the modeled cumulative number of aftershocks with time was fitted to observations by the least-squares criterion using the combined grid-search and Monte-Carlo approach. This enabled not only the estimation of the most probable ETAS parameters, but also the determination of their confidence limits, as well as the estimation of the bias between them. It has been found that the bias is significant for some of the parameter pairs, regardless of the threshold magnitude assumed. Residual analyses revealed that all strong aftershocks (M _L 4.5) occurred during the periods of normal to high aftershock activity. There were two periods of quiescence in the sequence, both of which were followed by a strong aftershock.     

<Superscript>57</Superscript>Fe Mössbauer spectroscopy,X-ray single-crystal diffractometry,and electronic structure calculations on natural alexandrite

Natural alexandrite Al₂BeO₄:Cr from Malyshevo near Terem Tschanka, Sverdlovsk, Ural, Russia, has been characterized by ⁵⁷Fe Mössbauer spectroscopy, electron microprobe, X-ray single-crystal diffractometry and by electronic structure calculations in order to determine oxidation state and location of iron. The sample contains 0.3 wt% of total iron oxide. The ⁵⁷Fe Mössbauer spectrum can be resolved into three doublets. Two of them with hyperfine parameters typical for octahedrally coordinated high-spin Fe³⁺ and Fe²⁺, respectively, are assigned to iron substituting for Al in the octahedral M2-site. The third doublet is attributed to Fe³⁺ in hematite. Electronic structure calculations in the local spin density approximation are in reasonable agreement with experimental data provided that expansion and/or distortion of the coordination octahedra are presumed upon iron substitution. The calculated hyperfine parameters of Fe³⁺ are almost identical for the M1 and M2 positions, but the calculated ligand-field splitting is by far too large for high-spin Fe³⁺ on M1.     

<Superscript>57</Superscript>Fe Mössbauer measurements and electronic structure calculations on natural lawsonites

Three natural lawsonites from Syke Rock, Mendocino Co., Reed Ranch, Marin Co., and Blake Gardens, Sonoma Co., all from the Coast Range Region in California, were studied by ⁵⁷Fe Mössbauer spectroscopy, electron microprobe analysis, and X-ray powder diffraction. The samples contain about 0.6, 1.0, and 1.4 wt% of total iron oxide, respectively. ⁵⁷Fe Mössbauer spectra are consistent with the assumption that high-spin Fe³⁺ substitutes for Al in the octahedrally coordinated site. The Mössbauer spectrum of lawsonite from Syke Rock exhibits a second doublet with ⁵⁷Fe hyperfine parameters typical for octahedrally coordinated high-spin Fe²⁺. Electronic structure calculations in the local spin density approximation yield quadrupole splittings for Fe³⁺ in quantitative agreement with experiment indicating, however, that substitution of Al by Fe³⁺ must be accompanied by local distortion around the octahedral site. Model calculations also reproduce the room temperature hyperfine parameters of ferrous high-spin iron assuming the substitution of Ca by Fe²⁺. However, it cannot be excluded that Fe²⁺ may occupy a more asymmetric site within the microstructural cavity occupied by Ca and a H₂O molecule.     

Physics of basic motions in asymmetric continuum

We consider the advantages of a formalism based on concept of the asymmetric continuum and we present some equivalence theorems relating it to the asymmetric elasticity and to micropolar and micromorphic theories as founded by Nowacki, Cosserats and Eringen. We consider the basic processes in an asymmetric continuum which could be reduced to the point basic motions/deformations. The co-action of spin and shear motions is assumed to play the main role in fracturing process, while the constitutive relation between the antisymmetric stresses and rotations replaces the friction constitutive law.     

我国春玉米水分供需状况分析

论述了作物需水量的概念及其计算方法，利用最新的气候和作物资料，计算了我国春玉米的作物需水量，分析其时空分布特征，并利用水发订正系来评价春玉米需水量的满足程度。计算分析结果表明，气候条件对我国在玉米生产是有利的，但在播种期、出苗期及拔节期（4－6月份），存在明显的水亏缺现象，这一时期应采取相应的栽培技术及节水灌溉、人工增雨等措施来缓解旱情。     

淮南矿区潘三矿构造发育规律定量研究

本文采用煤层构造形态空间分析、断裂要素数理统计分析等方法,并引入断裂分形维数指标作为刻划断裂构造发育强度的指标之一,对准南矿区潘三矿地质构造进行了定性—定量分析,揭示了矿井地质构造发育的南北分带性和东西分区性特征。     

沁水煤田霍东地区山西组主要煤层对比

运用标志层、层间距、物性特征、煤层本身特征等方法，对霍东地区沁安矿区和沁源矿区山西组1号、2号、3号煤层进行对比，认为沁安矿区未沉积3号煤层，该矿区现有的两个煤与沁源矿区的1号、2号煤层可比，而不是2号、3号煤层，其中既有定性又有定量，较成功的解决了南北两大矿区山本组主要可采煤层间的对比问题。     

熵气象学是动力气象学

论证“熵气象学”就是应用热力学第二定律的动力气象,是不足是统计出来的规律，所以它是气象学的发展。