Anomalous Trends Research Articles

Geometry and structure of northern surface ruptures of the 1999 Mw=7.6 Chi-Chi Taiwan earthquake: influence from inherited fold belt structures

Surface ruptures associated with the 1999 Mw=7.6 Chi-Chi earthquake in central western Taiwan have been characterised by mapping along the northern fault-segment. The earthquake occurred on the reactivated Chelungpu fault in the frontal portion of the thin-skinned Taiwan fold-and-thrust belt. The N–S trending Chelungpu fault is a 90-km-long major west-verging thrust, which principally slips within, and parallel to, bedding of the Pliocene Chinshui Shale. In the northern segment of the earthquake fault trace, that we name the Shihkang–Shangchi fault zone, the surface ruptures turn to an E–W strike and produce a series of thrust-and-backthrust pop-ups, about 15km long, forming several discontinuous subsegments distributed within a broad regional Pliocene syncline.The northern fault segments activated during the Chi-Chi earthquake, in the area where the displacement is largest, not only display anomalous trends and a variety of mechanisms, but also raise a major problem of structural inheritance. Detailed field investigation and kinematic analysis indicate that the surface ruptures in the Shihkang–Shangchi fault zone are the result of dip-slip thrusting, occasionally with a minor strike-slip component. The surface ruptures emerge at the surface from bedding-parallel thrusts on both limbs of the regional south-plunging syncline. In the middle part of the syncline, bedding-parallel thrusts are connected by thrusts that cross-cut beds. The surface ruptures also reactivate a NE–SW trending anticline (Diaoshenshan), with west-vergent thrust on the backlimb and east-vergent backthrust on the forelimb. This anticline is undergoing uplift by breaking through the regional N–S trending syncline.Combining GPS measurements, seismological data, and geological analyses, we propose a kinematic model with a 3-D fault surface for the 1999 earthquake in the area of the northern termination. We highlight the influence of both the local and regional structures (bedding parallel slip, pre-existing faults and folds) on the development of the earthquake rupture, and hence the role of the structural inheritance. We conclude that the south-plunging regional Pliocene syncline in fact acts as a slip/strain guide for the northern termination of the Chelungpu thrust. The Pliocene Chinshui Shale, as a major source of weakness within the syncline, has strongly influenced the pattern of slip surface during the 1999 earthquake rupture. We interpret the large vertical displacement along the northern segment as the fault rupture occurring over a surface whose radius of curvature tightens toward the north around the core of the syncline.

ATMOSPHERIC NEUTRINOS AND THE OSCILLATIONS BONANZA

New observations with atmospheric neutrinos from the underground experiments SuperKamiokande, Soudan 2, and MACRO, together with earlier results from Kamiokande and IMB, are reviewed. The most recent observations reconfirm aspects of atmospheric flavor content and of zenith angle distributions which appear anomalous in the context of null oscillations. The anomalous trends, exhibited with high statistics in both sub-GeV and multi-GeV data of the SuperKamiokande water Cherenkov experiment, occur also in event samples recorded by the tracking calorimeters. The data are well-described by disappearance of �µ flavor neutrinos arising in oscillations with dominant two-state mixing, for which there exists a region in (sin 2 2�, �m 2 ) allowed by all experiments. In a new analysis by SuperKamiokande, �µ → �� is favored over �µ → �sterile as the dominant oscillation based upon absence of oscillation suppression from matter effects at high energies. The possibility for sub-dominant �µ → �e oscillations in atmospheric neutrinos which arises with three-flavor mixing, is reviewed, and intriguing possibilities for amplification of this oscillation by terrestrial matter-induced resonances are discussed. Developments and future measurements which will enhance our knowledge of the atmospheric neutrino fluxes are briefly noted.

ABSTRACT: Geologic Mapping of Salt Mines in Salt Diapirs; Approaches and Examples from South Louisiana

Abstract Gulf Coast salt diapirs have complex internal structure, which is shown by light and dark layering. The layering reflects variation in anhydrite content and is interpreted to represent highly stretched and sheared depositional bedding. Structure is dominantly vertical, consisting of repeatedly refolded isoclinal folds having vertical plunge. Geologic mapping is conducted primarily as an aid to mine planning and development; separate maps are produced to record basic structure and display the distribution of clastic stringers, sylvite stringers and lenses, crystal size, wet areas, and gas. The latter characteristics, including coarse salt crystals, are anomalous and tend to be associated (in anomalous areas and trends). Gas is a mining hazard, causing Weeks Island and Cote Blanche Island to be classified by MSHA as gassy mines having many associated regulations. Five miners died in a gas explosion at Belle Isle mine in 1979, and blasting is now normally done while the mines are unoccupied (before the morning shift goes in, for example). Water influx, particularly if derived from outside the mine, is a cause of major concern for obvious reasons; at Avery Island a crew is constantly drilling and grouting to maintain control of leaks, and Jefferson Island mine has been lost as a result of flooding when penetrated by an oil rig. Sand reduces the salability of the commercial product and also increases mining costs. The geologic maps provide structural trend information to help the mine engineers avoid undesirable or potentially dangerous areas including those in proximity to the edge of the diapir. They also cast light on the nature of salt diapirism; linear anomalous zones have routinely been interpreted (sometimes with minimal justification) as boundaries between separate salt spines. Map examples from Weeks Island are included.

Astrolabe Solar Observations

AbstractSince 1978 at the Calern Observatory-France and from 1996 at the Observatório Nacional (O.N.)-Brasil solar observations have been carried out, aiming primarily to study the solar diameter. The ensemble of these two series is noteworthy by the length of Calern’s, which spans about two solar cycles, and by the high density of O.N.’s, with typically 20 observations per day, on each side of the meridian, all year around. The precision of a single measure is 015 for the northern hemisphere observations and 02 for the southern hemisphere observations.The characteristics of the combined series enabled detailed searches for anomalous trends (e.g., from atmospheric origin) and systematic bias (e.g., from instrumental origin). The analysis show the series robust for either. Thus there is a possiblity to investigate the variable time of transit of the solar disc across the almucantars of observation.The apparent solar time, defined by the actual diurnal motion of the Sun, shows variations because of the varying rate of motion of the Sun in hour angle. That is, due to the inequalities in the annual motion along the ecliptic and to the inclination of the ecliptic to the equator.In this work we detail the series characteristics and discuss the determination of the hour angle of the true Sun, as exemplified by the equation of time. The accuracy of the determination varies with the solar declination and the length of the observed apparent orbit. Typical precisions follow those for the semi-diameter determinations.

Anomalously rotated abyssal hills along active transforms: Distributed deformation of oceanic lithosphere

Abyssal hills within 20 km of the Clipperton and Pitman transforms deviate from regional trends by as much as 15°–20°. We use a thin viscous sheet model with power-law rheology to test the hypothesis that these anomalous trends result from distributed deformation of oceanic lithosphere, probably associated with periods of transpression. The variation of abyssal-hill trends with distance from the transform matches model predictions, with power-law exponents consistent with lithospheric rheology controlled by a combination of slip on faults at shallow depths and ductile creep in deeper parts. Predicted displacements are less than actual slip along the transforms, suggesting that only part of relative plate motion is taken up by distributed deformation. These results suggest that abyssal-hill rotation is sporadic, occurring perhaps when physical conditions (e.g., pore-fluid pressure, hydrothermal alteration, or transpression) are particularly favorable.

Anomalous trends in conductivity during epoxy—amine reactions

Measurements were carried out of conductivity due to migrating charges as a function of extent of reaction for a series of epoxy—amine formulations. All systems were characterised by the reaction mechanism common to this generic group of materials and by an increase in the steady shear viscosity during reaction. The measured conductivity, however. followed one of three distinct patterns as a function of extent of reaction. Intuitively unexpected, and hence particularly interesting, was the observed increase in conductivity during reaction in several formulations. This communication marks the first time that such response has been reported in the literature. An explanation of the observed trends was offered in terms of an interplay between the contributions of extrinsic and intrinsic migrating charges to the overall (measured) conductivity. Without such information, all correlations between the measured conductivity and the major processing parameters (viscosity, extent of reaction) remain strictly batch-specific and empirical.

PRESSURE STUDY OF THE FLACOURT FORMATION AQUIFER IN THE THEVENARD ISLAND AREA OF THE BARROW SUB-BASIN

Thevenard Island area lies in the offshore Carnarvon Basin off the northwest coast of Western Australia. The Flacourt Formation of the Cretaceous Barrow Group sequence is the primary oil-producing reservoir. West Australian Petroleum Pty Limited (WAPET) as operator on behalf of its participants (Chevron, Texaco, Shell and Mobil) has been producing from this reservoir since 1989. It has widely been held that in this area the relatively thick, multi-darcy Barrow Group oil accumulations have had infinite aquifer pressure support with no regional draw-down effect.After the commencement of oil production from the Flacourt Formation, wireline pressure surveys in exploration and development wells have indicated anomalous pressure trends in the reservoir. Initially, the accuracy of pressure gauges and elevation measuring devices were questioned.Recent studies based on WAPET's production history in the region and re-analysis of wireline pressure data have shown that the Flacourt Formation does experience regional draw-down in aquifer pressure due to production. This paper demonstrates the existence of draw-down and how this information has aided in the evaluation of the Flacourt Formation and the overlying Mardie Greensand reservoirs.

Low mortality from ischaemic heart disease in the Sámi district of Finland

Mortality from ischaemic heart disease (IHD) is compared between the Sámi (Lapp) and Finnish areas of northern Finland. During the period 1961–1990 male mortality from IHD was 41% lower in the predominantly Sámi area (Utsjoki) and 37% and 24% lower in two partially Sámi areas (Enontekiö and Inari, respectively) than in the purely Finnish reference area (Kittilä). The corresponding differences for females were 47%, 36% and 19%. Mortality figures diverged over time, the excess mortality increasing in the areas having the greatest percentages of Finns in their population and the deficit increasing in the area where the percentage of Sámi was greatest. The trends observed were paradoxical, since the risk factor pattern in the Sámi district is highly unfavourable, and the Finnicization of the Sámi in recent years should imply a convergence of mortalities rather than a divergence. It is concluded that the epidemic wave of IHD in Finland, which culminated in the early 1970s, showed a time lag in the north, especially in the Finnish and predominantly Finnish areas, while there is no indication that this epidemic ever reached Utsjoki, the core Sámi area. The reasons for the anomalous trends in IHD in the far north of Finland remain unknown, but the local diet may play a role in them.

Regional and Reservoir-Scale Analysis of Fault Systems and Structural Development of Pagerungan Gas Field, East Java Sea, Indonesia: ABSTRACT

Pagerungan gas field lies on a complexly faulted and folded anticline just north of the major Sakala-Paliat Fault System (SPFS) offshore Bali. The Eocene clastic reservoir is affected by two generations of faults: Eocene normal and Neogene compressional faults. Fault geometry, timing and connectivity is determined by combining regional and field-scale methods. Restored regional structure maps and sections indicate the field is located on the L. Eocene, footwall-paleo-high of the south-dipping SPFS. Within the field, smaller normal faults nucleated sub-parallel to the SPFS with both synthetic and antithetic dips. Neogene to Present compression folded the strata creating closure in the field, reversed slip on selected preexisting normal faults, and nucleated new reverse fault sets. Some normal faults are completely inverted, others have net normal offset after some reverse slip, and still others are not reactivated. Reverse faults strike sub-parallel to earlier formed normal faults. The eastern and western parts of the field are distinguished by the style and magnitude of early compressional deformation. 3D seismic analysis indicates the geometry of reservoir faults is similar to the regional fault systems: sub-parallel segments share displacement at their terminations either by distributed deformation in the rock between adjacent terminations or through short cross-faultsmore » oriented at a high angle to the principal fault sets. Anomalous trends in the contours of throw projected onto fault surfaces predict the connectivity of complex fault patterns. Integration of regional and field-scale analysis provides the most accurate prediction of fault geometry and lays the foundation for field development.« less

Chemometric Methods Applied to an ICP-AES Study of Chemical Element Distributions in Autopsy Livers from Subjects Affected by Wilson and β- Thalassemia

The concentrations of seven elements (Ca, Cu, Fe, Mg, P, S and Zn) in three autopsy livers (from two beta-thalassemic patients and one Wilson's disease patient) were determined by ICP-AES technique. At autopsy the three livers were subdivided into a large number of samples for a detailed study of the distribution of Fe and Cu, the accumulation of which characterizes the two diseases. In the same samples Ca, Mg, P, S and Zn concentrations were also determined in order to study significant variations or anomalous trends that could help identify these diseases. Our results generally show a good coincidence with literature data within the limits of sample variability. Based on Factor Analysis as well as Regression Analysis there is evidence of a high correlation between Fe and P contents in beta-thalassemia. The latter finding led us to propose tentatively an accumulation of Fe as a complex with P-containing molecules.

Humic acid–proton equilibria: A comparison of two models and assessment of titration error

SummaryCharge development curves, obtained by potentiometric titration of ten soil–derived humic acids, are described using two modelling approaches: a simple electrostatic model with limited functional group heterogeneity (model A), and an implementation of an alternative from the literature, model V, incorporating up to 12 functional group types. Both models provide excellent descriptions of charge dependence on pH and ionic strength. However, for model A, 11 fitted parameters were required to describe the data across the full range of ionic strength (0.01–3.0), compared with seven for model V. Although model A required more parameters, it was conceptually simpler than model V, requiring only two functional group types, which may have advantages in describing the formation of metal complexes.Error in the determination of humic charge from titration data was shown to increase markedly for data obtained at pH<3. The apparently anomalous trends in humic charge at low pH reported in the literature are explained in terms of this error.Investigation of the kinetics of protonation and deprotonation reactions of humic acids suggested that titration hysteresis was the result of dis–equilibrium, especially at high pH. The use of a 7‐day batch titration technique, instead of continuous titration apparently eliminated hysteresis from the data.

Combined surface and viscous flow of condensable vapor in porous media

The transport coefficient of cyclohexane vapor in an activated γ alumina pellet, estimated using the transient response method on a thermogravimetric analyzer (TGA), is reported as a function of relative saturation. An extended hydrodynamic model is proposed to account for the combined surface and viscous flows in coexisting adsorbed and capillary condensed phases, respectively, in a porous solid with a distribution of pore sizes. The structural features reflected in the isotherm data, as well as in the concentration dependence of the overall diffusivity, are well represented by the proposed model. The results are compared with the earlier hydrodynamic model. The model is also applied to published data, and anomalous trends reported in the literature are discussed.

Magnetic fabric of Pleistocene clays from the Tyrrhenian arc; A magnetic lineation induced in the final stage of the middle Pleistocene compressive event

We present the results of an analysis of the anisotropy of magnetic susceptibility (AMS) in early Pleistocene clay sediments from the southern Apennines and its foreland (Apulia). Measurements were performed on samples from different tectonic units; the Apulian Unit, the Bradano Unit, and the Apenninic belt. The AMS is characterized by a dominant magnetic foliation parallel to the bedding plane in all cases, pointing to a primary sedimentary magnetic fabric. No lineation is found in the clays from the Apulian Unit, whereas the inner part of the Bradano Unit and the Apenninic belt show a clear NW–SE trending magnetic lineation which is perpendicular to the main compressive stresses known for this area. There is a very consistent WNW‐ESE trending magnetic lineation for the clays from the southern Apennines and the Calabrian block to the south. Correction of this lineation with the established tectonic rotations shows that the lineation is clearly of postrotational origin and reflects the latest stages of deformation. The lineation is linked to middle and late Pleistocene tectonics: its alignment occurred in the final stages of the compressive event affecting the Tyrrhenian arc system. For the Sant'Arcangelo basin in the southern Apennines, anomalous trends of magnetic lineation (compressive stress) were established.

California's suicide decline, 1970-1990.

From 1970 to 1990 California experienced a 32% decline in suicide, which was particularly pronounced among women, non-whites, the young, and urban dwellers. Suicide declines of over 50% were recorded in San Francisco and Los Angeles, and large decreases occurred in other coastal counties. Additionally, California was the only one of 51 states to show a consistent decline in teenage and young-adult suicide (accompanied by an 88% decrease in teenage drug and other poisoning deaths). Initial investigation of death certification, accident and homicide trends, economic measures, and prevention efforts did not produce an explanation for a suicide decrease of California's magnitude. However, the state does display anomalous trends in certain social measures (reduced divorce, rising non-White population, and rising homicide) that point to multifactorial hypotheses including demographic changes and changed attitudes toward violence. Review of the accuracy of past suicide certification procedures nationally is also indicated.

Strike‐slip faulting and block rotation along the contact fault system, eastern Prince William Sound, Alaska

The Chugach and Prince William terranes compose a Mesozoic through Paleogene accretionary complex rimming the Gulf of Alaska. In eastern Prince William Sound, we studied the Contact fault system, which juxtaposes flysch of the latest Cretaceous Valdez Group (Chugach terrane) with flysch of the late Paleocene through early Eocene Orca Group (Prince William terrane). Near Valdez, we found three lithotectonic belts separated by right‐lateral strike‐slip faults. Anomalous structural trends between the two faults appear to be the result of clockwise block rotation in response to dextral shear. In a second area, to the east near Cordova, early formed folds were rotated clockwise before burial to depths sufficient to form axial‐planar cleavage. Apparently, synchronous thrusting and dextral‐slip faulting occurred during accretion. The relations above, combined with earlier studies, suggest that the fundamental nature of motion on faults composing the Contact fault system is dextral. Near Cordova, deposition, accretion, and block rotation occurred between early Eocene and early middle Eocene time. Near Valdez, block rotation appears to have occurred prior to accretion of the rocks near Cordova. Current plate tectonic models show that convergence became progressively more oblique during Eocene time, correlating well with the initiation of strike‐slip faulting. The presence of early Tertiary dextral‐slip faults, such as these, helps account for the northward displacement of the Chugach‐Prince William terrane with respect to the Peninsular and Wrangellia terranes suggested by paleomagnetic and geologic studies.

X-ray-diffraction study of the superliquid region of the phase diagram of a Langmuir monolayer.

Lipid-monolayer isotherms often show a kink that changes to a flat section and back to a kink within a narrow temperature range. In heneicosanoic acid monolayers, along a high-pressure isobar, we have observed a slightly distorted ``rotator-I'' phase between the known distorted hexagonal and hexagonal phases. Isotherms show a flat section only where this new phase occurs. The diffraction peaks are broader in this phase than in the adjacent phases; this reentrant behavior occurs in the same region of the phase diagram where the viscosity shows anomalous trends (first reported, we believe, by Copeland, Harkins, and Boyd [J. Chem. Phys. 10, 357 (1942)] and thought to indicate a ``superliquid'' phase).

Nd- and Sr-isotopic compositions of lavas from the northern Mariana and southern Volcano arcs: implications for the origin of island arc melts

Nd- and Sr-isotopic data are reported for lavas from 23 submarine and 3 subaerial volcanoes in the northern Mariana and southern Volcano arcs. Values of eNd range from +2.4 to +9.5 whereas 87Sr/86Sr ranges from 0.70319 to 0.70392; these vary systematically between and sometimes within arc segments. The Nd-and Sr-isotopic compositions fall in the field of ocean island basalt (OIB) and extend along the mantle array. Lavas from the Volcano arc, Mariana Central Island Province and the southern part of the Northern Seamount Province have eNd to +10 and 87Sr/86Sr=0.7032 to 0.7039. These are often slightly displaced toward higher 87Sr/86Sr at similar eNd. In contrast, those lavas from the northern part of the Mariana Northern Seamount Province as far north as Iwo Jima show OIB isotopic characteristics, with eNd and 87Sr/86Sr=0.7035 to 0.7039. Plots of 87Sr/86Sr and eNd versus Ba/La and (La/Yb)n support a model in which melts from the Mariana and Volcano arcs are derived by mixing of OIB-type mantle (or melts therefrom) and a metasomatized MORB-type mantle (or melts therefrom). An alternate interpretation is that anomalous trends on the plots of Nd- and Sr-isotopic composition versus incompatible-element ratios, found in some S-NSP lavas, suggest that the addition of a sedimentary component may be locally superimposed on the two-component mixing of mantle end-members.

Photointerpretation of Tertiary structures in platform cover strata of interior Oscar II Land, Spitsbergen

A structural map of Oscar II Land compiled using black and white, stereo-pair air photos and other available information sources suggests the existence of three structural zones within the deformed platform cover strata. The western zone consists of basement involved overthrusts of complex geometry in the north large-scale folds of platform cover strata with a stepped, down to the east profile in the south. The central zone consists primarily of folds within Kapp Starostin Fm. and overlying Triassic strata that likely formed above a subhorizontal decollement within Gipshuken Fm. strata. Farther to the east thrusts emplace Permian Kapp Starostin Fm. strata over Triassic strata. This zone probably represents stratigraphic climb of the basal decollement. Conservative estimates of shortening for the central and eastern zones are in the 15-25% range. The contribution of the western zone structures to overall Tertiary shortening depends on the geometry of faults underlying the stepped folds and is uncertain at present. Changes along strike are in part due to differential levels of erosion and changes in transport direction, but also probably important was variable thickness of the platform cover strata involved (less to the north) and the availability of incompetent horizons along which thrust-fiats could form. Two areas with anomalous structural trends may represent oblique ramps.

High-pressure studies on Ge-Te glasses. Evidence for a critical composition in IV-VI chalcogenide glassy systems

Abstract The electrical resistivity of bulk GexTe100-x glasses has been measured as a function of temperature and pressure. Under high pressure, all the glasses were found to undergo sharp discontinuous transitions from glassy semiconductors to crystalline metal. Several of the observed properties such as the transition pressure, conductivity activation energy and pre-exponential factor, exhibit anomalous trends at a composition x = 20. These results suggest that the x = 20 composition in the Ge-Te system should possess salient structural features. A model based on the unusual stability of structural units is proposed for explaining the anomaly at 20 at.% Ge concentration.

Stability Constants and Some Other Properties of the Lanthanoid Nitrate Complexes with Tri-, Tetra-, and Pentaethylene Glycols

Abstract The lanthanoid nitrate complexes of tri-, tetra-, and pentaethylene glycols (EO3, EO4, and EO5) exhibited anomalous stability trends attributed to structures similar to those of crown complexes. The stability constants of the EO4 and the EO5 complexes decreased with an increase in the atomic number of the lanthanoid in contrast to the lanthanoid complexes with most other ligands. A maximum stability was found at europium for EO3 complexes. The decomposition temperatures of EO3 complexes were higher than those of the corresponding EO4 and EO5 complexes. The yields of the solid complexes in reactions of the lanthanoids with EO5 decreased with an increase in the atomic number of the lanthanoid (with some exceptions). The separation factors observed for fractional precipitation using EO5 as the separating reagents were comparable to those reported regarding reagents practically used for lanthanoid separation.