Northridge Earthquake — Van Norman Complex Ground Movement

The January 17, 1994, Northridge Earthquake severely shook the Van Norman Complex, in the northern San Fernando Valley. Located in the nearfield, over the vicinity of the ruptured fault, the Van Norman Complex was subjected to many types of ground movements, including strong ground motions, tectonic displacements, ground deformation of natural soil deposits, and deformation of embankments and other engineered fills. The complex provides a well-documented case of how these various types of ground movements interact and their effects on engineered facilities. Throughout the complex, sand boils, liquefaction induced lateral spreading, and ground cracks were observed. Eleven water retaining embankments, including the Los Angeles Reservoir, underwent measurable movement. One small dike failed at the San Fernando Tailrace Channel at the northern end of the site. A great number of large diameter pipes and channels broke throughout the complex

A Tylosaurine Mosasauridae (Squamata) from the Late Cretaceous of the Basque-Cantabrian Region

An isolated mosasaurid tooth from the Campanian of Alava (Basque Country), previously referred to as cf. Mosasaurus sp., is here reattributed to a tylosaurine. It may belong to Tylosaurus, a nearly cosmopolitan genus known from the Santonian-Maastrichtian. This is the first occurrence of a tylosaurine mosasaurid in the Iberian Peninsula. Moreover, it corresponds to the southernmost occurrence of this clade in the northern margin of the Mediterranean Tethys. ylosaurinae fossils are known from North America, Europe, New Zealand, Antarctica, Africa and Asia, but remain unknown from the southern Mediterranean Tethyan margin and from tropical palaeolatitudes.Un diente aislado de mosasaurio procedente del Campaniense de Álava (País Vasco), previamente asignado a cf. Mosasaurus sp., se atribuye en este trabajo a un tilosaurino. Podría pertenecer a Tylosaurus, un género cuasi cosmopolita del Santoniense-Maastrichtiense. Es la primera cita de un mosasáurido tilosaurino en la Península Ibérica. Además, se trata del registro más meridional de este clado en el margen norte del Tetis mediterráneo. Los Tylosaurinae están representados por fósiles en Norteamérica, Europa, Nueva Zelanda, Antártida, África y Asia, pero carecen de registro en el margen sur del Tetis mediterráneo y en paleolatitudes tropicales

Spectral fluctuations of tridiagonal random matrices from the beta-Hermite ensemble

A time series delta(n), the fluctuation of the nth unfolded eigenvalue was recently characterized for the classical Gaussian ensembles of NxN random matrices (GOE, GUE, GSE). It is investigated here for the beta-Hermite ensemble as a function of beta (zero or positive) by Monte Carlo simulations. The fluctuation of delta(n) and the autocorrelation function vary logarithmically with n for any beta>0 (1<<n<<N). The simple logarithmic behavior reported for the higher-order moments of delta(n) for the GOE (beta=1) and the GUE (beta=2) is valid for any positive beta and is accounted for by Gaussian distributions whose variances depend linearly on ln(n). The 1/f noise previously demonstrated for delta(n) series of the three Gaussian ensembles, is characterized by wavelet analysis both as a function of beta and of N. When beta decreases from 1 to 0, for a given and large enough N, the evolution from a 1/f noise at beta=1 to a 1/f^2 noise at beta=0 is heterogeneous with a ~1/f^2 noise at the finest scales and a ~1/f noise at the coarsest ones. The range of scales in which a ~1/f^2 noise predominates grows progressively when beta decreases. Asymptotically, a 1/f^2 noise is found for beta=0 while a 1/f noise is the rule for beta positive.Comment: 35 pages, 10 figures, corresponding author: G. Le Cae

New ophthalmosaurid ichthyosaurs from the European lower cretaceous demonstrate extensive ichthyosaur survival across the Jurassic–Cretaceous boundary

Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous

One-dimension visco-elastic modelling of wood in the process of formation to clarify the Hygrothermal Recovery behavior of tension wood

International audienceWood production on stem by deposit of concentric layers on its periphery are going along with the setting up of growth stress. Growth stress has two origins: (1) loading due to weight of the structure is applied progressively when the tree is growing; (2) cell maturation, which happened at the end of the deposit of a new layer, causes an expansion, called maturation deformation, which can’t happen freely due to the previous layer and lead to the creation of initial growth stress [1]. The growth stress can be released during cutting and also during hygrothermal treatment (HT), it can be called Hygrothermal Recovery (HTR) [2]

Phase transition and correlation decay in Coupled Map Lattices

For a Coupled Map Lattice with a specific strong coupling emulating Stavskaya's probabilistic cellular automata, we prove the existence of a phase transition using a Peierls argument, and exponential convergence to the invariant measures for a wide class of initial states using a technique of decoupling originally developed for weak coupling. This implies the exponential decay, in space and in time, of the correlation functions of the invariant measures

Use of historical information in extreme-surge frequency estimation: the case of marine flooding on the La Rochelle site in France

Nuclear power plants located in the French Atlantic coast are designed to be protected against extreme environmental conditions. The French authorities remain cautious by adopting a strict policy of nuclear-plants flood prevention. Although coastal nuclear facilities in France are designed to very low probabilities of failure (e.g., 1000-year surge), exceptional surges (outliers induced by exceptional climatic events) have shown that the extreme sea levels estimated with the current statistical approaches could be underestimated. The estimation of extreme surges then requires the use of a statistical analysis approach having a more solid theoretical motivation. This paper deals with extreme-surge frequency estimation using historical information (HI) about events occurred before the systematic record period. It also contributes to addressing the problem of the presence of outliers in data sets. The frequency models presented in the present paper have been quite successful in the field of hydrometeorology and river flooding but they have not been applied to sea level data sets to prevent marine flooding. In this work, we suggest two methods of incorporating the HI: the peaks-over-threshold method with HI (POTH) and the block maxima method with HI (BMH). Two kinds of historical data can be used in the POTH method: classical historical maxima (HMax) data, and over-a-threshold supplementary (OTS) data. In both cases, the data are structured in historical periods and can be used only as complement to the main systematic data. On the other hand, in the BMH method, the basic hypothesis in statistical modeling of HI is that at least one threshold of perception exists for the whole period (historical and systematic) and that during a giving historical period preceding the period of tide gauging, only information about surges above this threshold have been recorded or archived. The two frequency models were applied to a case study from France, at the La Rochelle site where the storm Xynthia induced an outlier, to illustrate their potentials, to compare their performances and especially to analyze the impact of the use of HI on the extreme-surge frequency estimation

Regional frequency analysis of extreme storm surges along the French coast

A good knowledge of extreme storm surges is necessary to ensure protection against flood. In this paper we introduce a methodology to determine time series of skew surges in France as well as a statistical approach for estimating extreme storm surges. With the aim to cope with the outlier issue in surge series, a regional frequency analysis has been carried out for the surges along the Atlantic coast and the Channel coast. This methodology is not the current approach used to estimate extreme surges in France. First results showed that the extreme events identified as outliers in at-site analyses do not appear to be outliers any more in the regional empirical distribution. Indeed the regional distribution presents a curve to the top with these extreme events that a mixed exponential distribution seems to recreate. Thus, the regional approach appears to be more reliable for some sites than at-site analyses. A fast comparison at a given site showed surge estimates with the regional approach and a mixed exponential distribution are higher than surge estimates with an at-site fitting. In the case of Brest, the 1000-yr return surge is 167 cm in height with the regional approach instead of 126 cm with an at-site analysis