Application of non-stationary Poisson model prediction on seismic belts in northwestern of China

Earthquake probability prediction is based on earthquakes occurred in a certain seismo-tectonic region to predict the probable times and probability of certain magnitude segment earthquake or the earthquake whose mag-nitude is larger than certain magnitude low limit in the coming certain period, this was extensively applied to earthquake risk analysis and earthquake forecast. The main characteristics of the method are that when earthquake statistical model was founded according to the occurred …     

Application of a time-magnitude prediction model for earthquakes

In this paper we discuss the physical meaning of the magnitude-time model parameters for earthquake prediction. The gestation process for strong earthquake in all eleven seismic zones in China can be described by the magnitude-time prediction model using the computations of the parameters of the model. The average model parameter values for China are： b = 0.383, c=0.154, d = 0.035, B = 0.844, C = -0.209, and D = 0.188. The robustness of the model parameters is estimated from the variation in the minimum magnitude of the transformed data, the spatial extent, and the temporal period. Analysis of the spatial and temporal suitability of the model indicates that the computation unit size should be at least 4°× 4°for seismic zones in North China, at least 3° × 3° in Southwest and Northwest China, and the time period should be as long as possible.     

Distribution of clay minerals in marine sediments off Chennai,Bay of Bengal,India： Indicators of sediment sources and transport processes

Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared （FTIR） spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides （magnetite and hematite） derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses （correlation, cluster and factor analyses） were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.     

The changes in La Niña induced summertime interannual variability of sea level anomaly along the western boundary of the Bay of Bengal

Ocean Dynamics - In this study, interannual variability and associated dynamics of sea level anomaly (SLA) along the western boundary of the Bay of Bengal (WBoB) during the summer...     

Improved stress release model: Application to the study of earthquake prediction in Taiwan area

Introduction Stress release model (SRM) was proposed by Vere-Jones (1978) for statistical study of seismicity. Physically it is a stochastic version of the elastic rebound theory of earthquake genesis. The classical elastic rebound model suggests that the stress has been slowly accumulating until the burst of an earthquake occurrence for stress release. This can be simulated by the jump Markov process in stochastic field, and SRM was developed on the basis of Knopoff (s Markov model (Knop…     

Parker’s model in geodynamo

The eigenvalue problem for Parker’s dynamo model is considered. We study how the intensity of convection in the liquid core of the Earth affects the generation of the geomagnetic field with different directions of latitudinal field propagation. The scenarios of transition of the geomagnetic field from frequent to rare reversals are suggested.     

Implementation of a wetting-and-drying model in simulating the Kennebec–Androscoggin plume and the circulation in Casco Bay

A high-resolution coastal ocean model was developed to simulate the temporal/spatial variability of the Kennebec–Androscoggin (K–A) river plume and the circulation in Casco Bay. The model results agree favorably with the moored and shipboard observations of velocity, temperature, and salinity. The surface salinity gradient was used to distinguish the plume from the ambient coastal water. The calculated plume thickness suggests that the K–A plume is surface trapped. Its horizontal scales correlate well with Q ^0.25, where Q is the volume discharge of the rivers. Directional spreading is affected by the wind with the upwelling favorable wind transporting the plume water offshore. Both the wind and the tide also enhance mixing in the plume. The inclusion of a wetting-and-drying (WAD) scheme appears to enhance the mixing and entrainment processes near the estuary. The plume becomes thicker near the mouth of the estuary, the outflow velocity of the plume is weaker, and the radius of the river plume shrinks. The flow field in the model run with the WAD is noisier, not only in shallow areas of Casco Bay but also in the plume and even on the shelf. We speculate that the WAD processes can affect much larger areas than the intertidal zones, especially via a river plume that feeds into a coastal current.     

Application of apparent stress in earthquake prediction

On the basis of the assumption that ω2 model accords with source displacement spectra of moderate-small shocks, we calculate the apparent stress values of 1 020 moderate-small shocks recorded by the Digital Seismic Network of Yunnan Province by using the low-frequency flat level and corner frequencies. The results show that the apparent stress is of good significance in earthquake prediction. The moderate-small shock with apparent stress larger than 0.9 MPa can be used as a referential index to predict moderate-strong earthquakes in Yunnan area. And its relevant predictability evaluation (R value) has a high confidence level.     

Macrophytes’ Performance in Floating Treatment Wetlands for the Remediation of Ciprofloxacin-Contaminated Water

The presence of trace antibiotics in domestic and industrial effluents poses a risk of toxicity to fauna and flora. The application of floating treatment wetlands (FTWs) is a low-cost and sustainable approach to remediate wastewater. In this study, the performance of different macrophytes vegetated in FTWs for the remediation of ciprofloxacin (CIP)-contaminated water is investigated. Six macrophytes, Brachia mutica, Typha domingensis, Phragmites australis, Canna indica, Cyperus laevigatus, and Leptochloa fusca, are vegetated in FTWs for the removal of CIP (50 mg L⁻¹) from water. The FTWs show the potential to remove 30–43.58 mg L⁻¹ CIP from water in 28 days. They also reduce the chemical oxygen demand (118–138 mg L⁻¹) and biochemical oxygen demand (35–45 mg L⁻¹) of water. Among the macrophytes, C. indica removes maximum (43.58 mg L⁻¹) and T. domingensis minimum (30 mg L⁻¹) CIP. Canna indica and T. domingensis exhibit the maximum and minimum increase (30% and 12% of dry biomass) in growth, respectively. This study reveals that the FTWs vegetated with different plant species exhibit varying performances in removing CIP from water. This investigation is a step forward toward sustainable bioremediation of water contaminated with antibiotics.     

Performance of the COSERO precipitation–runoff model under non-stationary conditions in basins with different climates

Abstract

This study is a contribution to a model intercomparison experiment initiated during a workshop at the 2013 IAHS conference in Göteborg, Sweden. We present discharge simulations with the conceptual precipitation–runoff model COSERO in 11 basins located under different climates in Europe, Africa and Australia. All of the basins exhibit some form of non-stationary conditions, due, for example, to warming, droughts or land-cover change. The evaluation of the daily discharge simulations focuses on the overall model performance and its decomposition into three components measuring temporal dynamics, mean flow volume and distribution of flows. Calibration performance is similarly high as in previous COSERO applications. However, when looking at evaluation periods independent of the calibration, the model performance drops considerably, mainly due to severely biased discharge simulations in semi-arid basins with strong non-stationarity in rainfall. Simulations are more robust in European basins with humid climates. This highlights the fact that hydrological models frequently fail when simulations are required outside of calibration conditions in basins with non-stationary conditions. As a consequence, calibration periods should be sufficiently long to include both wet and dry periods, which should yield more robust predictions.     

Discharge of Salt Groundwater in the Estuary of the Razdol’naya River (Amur Bay) in February 2020

Water Resources - In February 2020, geochemical tracers along with hydrochemical and hydrological characteristics were used to reveal a discharge site of salt groundwaters in the head of the...     

Towards real-time eruption forecasting in the Auckland Volcanic Field: application of BET_EF during the New Zealand National Disaster Exercise ‘Ruaumoko’

The Auckland Volcanic Field (AVF) is a young basaltic field that lies beneath the urban area of Auckland, New Zealand’s largest city. Over the past 250,000 years the AVF has produced at least 49 basaltic centers; the last eruption was only 600 years ago. In recognition of the high risk associated with a possible future eruption in Auckland, the New Zealand government ran Exercise Ruaumoko in March 2008, a test of New Zealand’s nation-wide preparedness for responding to a major disaster resulting from a volcanic eruption in Auckland City. The exercise scenario was developed in secret, and covered the period of precursory activity up until the eruption. During Exercise Ruaumoko we adapted a recently developed statistical code for eruption forecasting, namely BET_EF (Bayesian Event Tree for Eruption Forecasting), to independently track the unrest evolution and to forecast the most likely onset time, location and style of the initial phase of the simulated eruption. The code was set up before the start of the exercise by entering reliable information on the past history of the AVF as well as the monitoring signals expected in the event of magmatic unrest and an impending eruption. The average probabilities calculated by BET_EF during Exercise Ruaumoko corresponded well to the probabilities subjectively (and independently) estimated by the advising scientists (differences of few percentage units), and provided a sound forecast of the timing (before the event, the eruption probability reached 90%) and location of the eruption. This application of BET_EF to a volcanic field that has experienced no historical activity and for which otherwise limited prior information is available shows its versatility and potential usefulness as a tool to aid decision-making for a wide range of volcano types. Our near real-time application of BET_EF during Exercise Ruaumoko highlighted its potential to clarify and possibly optimize decision-making procedures in a future AVF eruption crisis, and as a rational starting point for discussions in a scientific advisory group. It also stimulated valuable scientific discussion around how a future AVF eruption might progress, and highlighted areas of future volcanological research that would reduce epistemic uncertainties through the development of better input models.     

Data assimilation in Parker’s dynamo model

Application of the extended Kalman filter in the data assimilation problem of the one-dimensional (1D) Parker dynamo model is considered for two extreme cases: (1) when the magnetic field observations are taken uniformly across the entire surface of the liquid core of the Earth and (2) when the observations are taken at one spatial point. The algorithm allows the model solution with arbitrary initial conditions to be modified based on observations. It is shown that the redundancy of the noised data can reduce the efficiency of the recovery of the solution. Considerations on the applicability of data assimilation for the case of a higher dimension and a solution’s convergence dependent on the density of the flow of information assimilated are suggested.     

Time-scales of recent Phlegrean Fields eruptions inferred from the application of a ‘diffusive fractionation’ model of trace elements

The variation of chemical element compositions in two pyroclastic sequences (Astroni 6 and Averno 2, Phlegrean Fields, Italy) is studied. Both sequences are compositionally zoned indicating a variability of melt compositions in the magma chamber prior to eruption. A clear dichotomy between the behaviour of major vs. trace elements is also observed in both sequences, with major elements displaying nearly linear inter-elemental trends and trace elements showing a variable scattered behaviour. Together with previous petrological investigations these observations are consistent with the hypothesis that magma mixing processes played a key role in the evolution of these two magmatic systems. Recently it has been suggested that mixing processes in igneous systems may strongly influence the mobility of trace elements inducing a ‘diffusive fractionation’ phenomenon, whose extent depends on the mixing time-scale. Here we merge information from 1) numerical simulations of magma mixing, and 2) magma mixing experiments (using as end-members natural compositions from Phlegrean Fields) to derive a relationship relating the degree of ‘diffusive fractionation’ to the mixing time-scales. Application of the ‘diffusive fractionation’ model to the two studied pyroclastic sequences allowed us to apply the relationship derived by numerical simulations and experiments to estimate the mixing time-scales for these two magmatic systems. Results indicate that mixing processes in Astroni 6 and Averno 2 systems lasted for approximately 2 and 9 days, respectively, prior to eruption.     

An observational analysis of the evolution of a mesoscale anti-cyclonic eddy over the Northern Bay of Bengal during May–July 2014

The Bay of Bengal (BoB) is a distinct oceanic region for mesoscale oceanic eddies. The sea level anomaly from the Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) help to identify an unusual anti-cyclonic eddy (ACE) over head BoB during May–July 2014. Two Indian moored buoys (BD08 and BD09) located over this region aided to study the subsurface thermohaline structures of the ACE. Compared to no-eddy environment, the temperature and salinity showed an increment of ~?3–4 °C and ~?1–2 PSU, respectively, during the ACE life period. The temperature and depth of the isothermal layer at genesis (peak) stages are increased to ~?30 °C (~?30.7 °C) and ~?20 m (30 m) when compared with no-eddy conditions (28.2 °C and 10 m). The thermocline depth is deepened to 75 m at the peak stage, while it is 50 m in no-eddy condition. A temperature difference of 3 °C between no-eddy and peak stages of ACE is observed up to 50 m. The ocean heat content (OHC) at BD08 (BD09) during genesis and peak stages has increased by ~?72% (~?50%) and ~?247% (~?181%), respectively, when compared with no-eddy conditions. Moreover, the MOHC also shows a similar increment of ~?125% (~?123%) and ~?258% (~?284%), respectively. A noticeable influence is seen in turbulent fluxes and lower atmospheric variables during eddy life. This study highlights the capability of moored buoys in understanding the subsurface thermohaline features of the eddies over northern BoB.     

Petrologic composition model of the upper crust in Bohai Bay basin, China, based on Lamé impedances

Seismic attributes, such as P- and S-wave velocity, Poisson’s ratio, and acoustic impedances, all generally can be used for distinguishing different rock types. The non-uniqueness can be largely reduced using Lamé impedances instead of acoustic impedances as additional constraints. We have followed this method to constitute a petrologic composition model of the upper crust in the Bohai Bay basin, China. We briefly review the seismic parameters used for discrimination of rock types and focus our attention on the sensitivity of different combinations of parameters to determine the composition of materials. Corrections for pressure and temperature are performed in order to compare elastic wave velocities and densities measured at room temperature and surface pressure in laboratory with those for representative rock parameters. In a second step, we find the rock classes in the tested area by contrasting known data to laboratory measurements on a variety of rock samples extracted in the area. The basic field data are P-wave velocity values collected along a seismic profile conducted in the Bozhong Depression. The different rock types belonging to a particular rock class are finally constrained by the seismic velocities, Poisson’s ratio, density, acoustic impedance, and Lamé impedance related to the topmost 10 km of the Bohai Bay crust.     

Vertical motion and diabatic heating over the Indian monsoon region during the Bay of Bengal depression of 5–8 July, 1979

The vertical velocity, , and the diabatic heating were computed at 800, 600, 400 and 200 mb surfaces using the Omega equation. The highest contribution to is from the diabatic heating produced by condensation associated with the precipitations appearing to be the main source of diabatic heating. The net radiative cooling and the thermal advection in the upper troposphere over the warm anticyclone result in diabatic cooling over the eastern part of the Bay of Bengal and adjoining northern and eastern regions.List of Symbols Used C _p Heat capacity at constant pressure - f Coriolis parameter - g Acceleration due to gravity - P Atmospheric pressure - Q Diabatic heating rate per unit mass - R Gas constant of air - S Static stability parameter - t Time - U, V Zonal and meridional wind components - Specific volume - Relative vorticity - Absolute vorticity - Potential temperature - Geopotential - Vertical velocity (dP/dt) - ₁ Adiabatic vertical velocity - ₂ Vertical velocity due to certain forcing - ₃ Diabatic vertical velocity - Isobaric gradient operator - ² Laplacian operator - J(A, B) Jacobian operator