Time Series Analysis on the Ratio for Pixels with Abnormal Brightness Temperature Increase and Its Variation Before Some Earthquakes with Ms ≥ 5.0 in the Taiwan Area

In the study of the application of MODIS satellite remote sensing data to earthquake prediction, the paper puts forward for the first time a quantitative method to estimate the ratio for the pixels with abnormal brightness temperature (BT) increase and a preliminary scheme for cloud removal. The principle is that, firstly, the cloudless data observed by the same satellite at the same period of time but in different days (usually 1 day to 3 days) are mosaiced to get high ratio of clear sky, and then the BT variation curve and mean square difference (MSD) of each pixel are calculated with the data from the covered area to determine daily whether the BT data of the day is normal or not at a certain pixel by using double the MSD as the criterion. The ratio for the pixels with abnormal BT increase can be calculated by dividing the total number of abnormal pixels with the total pixels of the whole area. Analysis on a series of recent earthquakes in the Taiwan area shows that the ratio for pixels with abnormal BT increase, which normally undulates around zero, has a sudden enhancement 1 day to 20 days before medium-strong earthquakes. It is expected that a new method for identifying earthquake auspice could be found through special studies in regions with frequent seismic activity by analyzing the change of the ratio for the pixels with abnormal BT increase from MODIS satellite remote sensing infrared (IR) information from which the effect of clouds has been removed to a certain extent.     

Time Series Analysis on the Ratio for Pixels with Abnormal Brightness Temperature Increase and Its Variation Before Some Earthquakes with Ms ≥ 5.0 in the Taiwan Area

In the study of the application of MODIS satellite remote sensing data to earthquake prediction, the paper puts forward for the first time a quantitative method to estimate the ratio for the pixels with abnormal brightness temperature (BT) increase and a preliminary scheme for cloud removal. The principle is that, firstly, the cloudless data observed by the same satellite at the same period of time but in different days (usually 1 day to 3 days) are mosaiced to get high ratio of clear sky, and then the BT variation curve and mean square difference (MSD) of each pixel are calculated with the data from the covered area to determine daily whether the BT data of the day is normal or not at a certain pixel by using double the MSD as the criterion. The ratio for the pixels with abnormal BT increase can be calculated by dividing the total number of abnormal pixels with the total pixels of the whole area. Analysis on a series of recent earthquakes in the Taiwan area shows that the ratio for pixels with abnormal BT increase, which normally undulates around zero, has a sudden enhancement 1 day to 20 days before medium-strong earthquakes. It is expected that a new method for identifying earthquake auspice could be found through special studies in regions with frequent seismic activity by analyzing the change of the ratio for the pixels with abnormal BT increase from MODIS satellite remote sensing infrared (IR) information from which the effect of clouds has been removed to a certain extent.     

Space–Time Analysis of Hydrochemical Composition and Pollution of Water in the Northern Dvina Basin

Water Resources - Water quality dynamics along the Northern Dvina River is analyzed under the conditions of anthropogenic impact. Overall, river water is classified as very polluted. The cases of...     

Earthquake—Affected Time—Space Domain,Recurrence Interval and Effective Preparation Time of Earthquakes

The study shows that earthquake-affected time-space domain(ETSD),i.e.a time-space range in which strong earthquakes are unable to occur owing to the influence of a prior earthquake occurring,shows a hyperbolic margin curve in the t(time)-r(distance)coordinate plane,which has a maximum affected radius r0 at t=0 and a maximum influence time t0(i.e.the insitu recurrence interval of earthquakes)at r=0.Based on the time-distance distributions of posterior earthquakes relative to pror ones in the regions of North China,Northwest China,Qinghai-Xizang(Tibet)plateau and Southwest China,the optimized and 90%-confidence margin curves are estimated using optimization and statistical analysis methods.This indicates that the concept and method of ETSD with 3-dimension(time-distance-magnitudes)instead of those of “recurrence interval “with 1-dimension(time)or 2-dimension(time-magnitude) provides a new approach to understanding the fluctuation of seismic activities,estimating the effective earthquake-preparation time of potential hypocenters,and therefore improving the mediumand long-term prediction of strong earthquakes.     

Temporal and Spatial Characteristics of Seismicity in Northeastern China and Its Neighboring Region

Analysis of macroseismicity in the northeastern Japan trench,the intermediate and deep focus earthquakes in and near the Japan Sea,the shallow earthquakes in the Northeast China and the peripheral earthquakes of the Amurian plate(Zonenshain et al,1981)indicates that there is a good temporal correlation among these different types of earthquakes.By means of further studying the behavior in detail and investigating the mutual relation among several Asian microplates,as well as the focal mechanism solutions of the intermediate and deep focus earthquakes,we concluded that the main source power for all types of the earthquake may come from strong action of the Pacific plate,through the northeastern arc of the Japan islands,on the Amurian plate.This action is a kind of extrusive process,which caused the Amurian plate to buckle.It is reasonable to assume that the deformation of the Amurian plate was the reason for the linear configuration of Ms≥6.0 earthquake distribution in northeastern China.     

Temporal and spatial dynamical simulation of groundwater characteristics in Minqin Oasis

Application scope of geostatistics has been gradually extended from original geologic field to soil science and ecological field, etc. and its successful application results have been widely demonstrated. But little information is reported as to the direct use of geostatistical method to work out the distribu- tion map of groundwater characteristics. In this paper the semivariogram of geostatistics, in combina- tion with GIS, was used to quantitatively study the spatial variation characteristics of groundwater table depth and mineralization degree and their relation to the landuse changes. F test of the used spherical model reached a very significant level, and the theoretical model can well reflect the spatial structural characteristics of groundwater table depth and mineralization degree and achieve an ideal result. This shows that the application of the method in the dynamical simulation of groundwater is feasible. And this paper also provides useful reference for the application of geostatistics in the study of the dy- namical variations of groundwater resources in the oasis.     

On the Occurrence Time of an Earthquake Cluster in the Shanxi Reservoir

INTRODUCTIONEarthquake induced byreservoir is a kind of crust motion andis an outcome of the joint functionof current crustal movement andreservoir storage .The cause of reservoir-induced earthquakesincludesthe decrease of strengthand elasticity modulus of rockonthe one hand,andthe decrease of friction offault surface because of water permeation onthe other .The more large-scale reservoirs built ,the more reservoir-induced earthquakes will happen.As iswell known,reservoir-induced earthqua…     

The Temporal Variation of LURR in Kanto and Other Regions in Japan and Its Application to Earthquake Prediction

The temporal variation of LURR(y)for Kanto,Wakayama,and Hugo regions in Japan has been calculated and analysed.The LURR(y)values are significantly higher than 1 before the occurrence of all earthquakes with magnitude M≥6.0 in the Kanto region during the last two decades and the Kobe earthquake(1995-01-17).These results suggest that LURR theory is available for Japan.Recently they-value for Wakayama region has been near 1,while the y-value is remarkably larger than 1 for nearly two years for Kanto.According to these results,it is predicted that a strong earthquake with magnitude of about 6.0 could occur in 1 year or a little longer for in Kanto region or its adjacent regions,but there is little possibility for the Wakayama region.     

Temporal and spatial variations of seismicity scaling behavior in Southern México

R/S analysis is used in this work to investigate the fractal correlations in terms of the Hurst exponent for the 1998–2011 seismicity data in Southern Mexico. This region is the most seismically active area in Mexico, where epicenters for severe earthquakes (e.g., September 19, 1985, M_w = 8.1) causing extensive damage in highly populated areas have been located. By only considering the seismic events that meet the Gutenberg–Ritcher law completeness requirement (b = 0.97, M_GR = 3.6), we found time clustering for scales of about 100 and 135 events. In both cases, a cyclic behavior with dominant spectral components at about one cycle per year is revealed. It is argued that such a one-year cycle could be related to tidal effects in the Pacific coast. Interestingly, it is also found that high-magnitude events (M_w ≥ 6.0) are more likely to occur under increased interevent correlations with Hurst exponent values H > 0.65. This suggests that major earthquakes can occur when the tectonic stress accumulates in preferential directions. In contrast, the high-magnitude seismic risk is reduced when stresses are uniformly distributed in the tectonic shell. Such cointegration between correlations (i.e., Hurst exponent) and macroseismicity is confirmed for spatial variations of the Hurst exponent. In this way, we found that, using the Hurst exponent standpoint, the former presumed Michoacan and the Guerrero seismic gaps are the riskiest seismic zones. To test this empirical finding, two Southern Mexico local regions with large earthquakes were considered. These are the Atoyac de Alvarez, Guerrero (M_w = 6.3), and Union Hidalgo, Oaxaca (M_w = 6.6), events. In addition, we used the Loma Prieta, California, earthquake (October 17, 1989, M_w = 6.9) to show that the high-magnitude earthquakes in the San Andreas Fault region can also be linked to the increments of determinism (quantified in terms of the Hurst exponent) displayed by the stochastic dynamics of the interevent period time series. The results revealed that the analysis of seismic activity by means of R/S analysis could provide further insights in the advent of major earthquakes.     

Comparison of River Terraces in the Middle Reach Valleys of the Yellow River and Analysis on the Multi-Gradational Features of Tectonism in the Formation of Terrace Series

Where the Yellow River flows through the Haiyuan-Tongxin arc-form tectonic region on the northeastern side of the Qinghai-Xizang (Tibet) Plateau, as many as 10～21 basis and erosion terraces have been produced, among which the biggest altitude above river level is 401m and the formation age of the highest terrace is 1.57 Ma B.P. Based on comparative analysis of the Yellow River terraces located separately in the Mijiashan mountain, the Chemuxia gorge, the Heishanxia gorge and the other river terraces in the vast extent of the northern part of China, it has been found that the tectonic processes resulting in the formation of the terrace series is one of multi-gradational features, i.e., a terrace series can include the various terraces produced by tectonic uplifts of different scopes or scales and different ranks. The Yellow River terrace series in the study region can be divided into three grades. Among them, in the first grade there are 6 terraces which were formed separately at the same time in the vast extent of the northern part of China and represent the number and magnitude of uplift of the Qinghai-Xizang Plateau since 1.6 Ma B. P. ; in the second grade there are 5 terraces which were separately and simultaneously developed within the Haiyuan-Tianjingshan tectonic region and represent the number and magnitude of uplift of this tectonic region itself since 1.6Ma B. P.; in the third grade there are 10 terraces which developed on the eastern slope of the Mijiashan mountain and represent the number and amplitude of uplift of the Haiyuan tectonic belt itself since 1.6Ma B.P. Comparison of the terrace ages with loess-paleosoil sequence has also showed that the first grade terraces reflecting the vast scope uplifts of the Qinghai-Xizang Plateau are very comparable with climatic changes and their formation ages all correspond to the interglacial epochs during which paleosoils were formed. This implies that the vast extent tectonic uplifts resulting in river down-cutting are closely related to the warm-humid climatic periods which can also resnit in river downward erosion after strong dry and cold climatic periods, and they have jointly formed the tectonic-climatic cycles. There exists no unanimous and specific relationship between the formation ages of the second and third grade terraces and climatic changes and it is shown that the formation of those terraces was most mainly controlled by tectonic uplifts of the Tianjingshan block and the Haiyuan belt. The river terraces in the study region, therefore, may belong to 2 kinds of formation cause. One is a tectonic-climatic cyclical terrace produced jointly by vast extent tectonic uplifts and climatic changes, and the terraces of this kind are extensively distributed and can be well compared with each other among regions. Another is a pulse-tectonic cyclical terrace produced by local tectonic uplifts as dominant elements, and their distribution is restricted within an active belt and can not be compared with among regions.     

Temporal vP/vS variation characteristics in different zones of China’s Capital Circle area before and after Wen’an earthquake

On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of r...     

Temporal variation in community–environment relationships and stream classifications in benthic diatoms: Implications for bioassessment

Diatom based biomonitoring tools are proven to be a practical way to indicate stream conditions, but only little is known how stable diatom inferred stream classifications are in time. We studied annual variation in diatom community–environment relationships, community structure and diatom indices (Index of Pollution Sensitivity, IPS and Trophic Diatom Index, TDI) during three consecutive years (2010–2012) in four drainage basins distributed in Finland. We also used a cluster analysis to examine if stream classifications resulted in distinct and temporally stable community types. We found only subtle temporal variation in community–environment relationships, nutrient concentrations (N, P) and conductivity consistently being the main factors structuring communities. According to Mantel tests, diatom communities resembled each other significantly at different years, and the values of IPS and TDI indices remained relatively stable in the basins through time. The stream classification based on diatoms also resulted in temporally stable and statistically distinct community types. We thus suggest that sampling of diatoms, e.g., in every three years seems to be a reliable procedure to assess biological water quality. Generally, to choose the correct metrics to assess water quality is essential, and both biological and physicochemical factors should be considered.     

Temporal vP/vS variation characteristics in different zones of China’s Capital Circle area before and after Wen’an earthquake

On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in- volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen’an and Tangshan underwent a normal-low-normal proc- ess one year before Wen’an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen’an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen’an and Tangshan be- fore Wen’an earthquake.     

Temporal and spatial variation and stability of the oasis in the Sangong River Watershed, Xinjiang, China

The unique ecological landscapes are composed of the mountain systems with the obviousvertical differentiation, vast natural desert systems, and oasis systems on which the human beings rely for the existence in the arid areas in West China. Oases are the …     

Analysis and study of the large earthquake risk in Yanqing-Huailai basin

ＡｎａｌｙｓｉｓａｎｄｓｔｕｄｙｏｆｔｈｅｌａｒｇｅｅａｒｔｈｑｕａｋｅｒｉｓｋｉｎＹａｎｑｉｎｇＨｕａｉｌａｉｂａｓｉｎＣＨＡＮＧＱＵＡＮＬＩＵ（刘昌铨）ＳＨＩＸＵＪＩＡ（嘉世旭）ＭＩＮＧＪＵＮＬＩＵ（刘明军）ＣＨＡＮＧＦＡＬＩ（李长发...     

Phase Space Structure, Attractor Dimension, Lyapunov Exponent and Nonlinear Prediction from Earth’s Atmospheric Angular Momentum Time Series

--On a short time scale, Atmospheric Angular Momentum (AAM) has been demonstrated to be essentially the sole excitation source of LOD variations. The LOD variation, therefore, merely reflects the AAM variation (LOD as proxy for AAM). The study of the nonlinear nature of AAM variability (e.g., its orbital complexity, dimensionality and extreme sensitivity to the initial conditions) may provide a physical premise for theoretical modelling of the earth-atmosphere-ocean system. Analysis of the high quality of detailed daily LOD/AAM variations time series, spanning the period of 1962-1992, reveals a non-zero and low positive Lyapunov exponent value which suggests possible evidence of deterministic chaos in the underlying dynamics. Application of modern nonlinear prediction techniques capable of distinguishing chaos and random fractals to the data set, further support the above findings and render a predictive time limit of approximately 12-15 days. A low dimensional strange attractor and a low average Lyapunov exponent suggest a low level of unpredictability and stability in the system dynamics. It is argued here that a possible source of the raised entropy in LOD/AAM systems possibly stems from a conceivable nonlinear interaction between the seasonal cycle and inter- or intra-annual fluctuations due to thermodynamics properties of the atmosphere-ocean system.     

Analysis of recent changes in rainfall and drought indices in Nigeria, 1981–2015

ABSTRACT

This study assesses the climate change impact on rainfall and drought incidents across Nigeria. Linear regression, Mann-Kendall tests and lag-1 serial correlation were adopted to analyse the trends and variability of rainfall and drought at 18 synoptic stations. Analysis of annual precipitation series indicates an increase in rainfall amounts at all stations, except Minna, Gusau and Yola. Seventeen of the 18 stations recorded at least one main drought period, between 1983 and 1987. A decreasing trend for the standardized precipitation index SPI-12 series was seen at Yola station, while the other stations showed an increasing trend. Also, Nigeria witnessed more annual rainfall totals but with high variability within the rainy months of the year in the first 15 years of the 21st century compared to the 20th century. Such variability in rainfall may have a significant effect on groundwater resources and the hydrology of Nigeria.     

A study on an oligotrophic bacteria and its ecological characteristics in an arid desert area

An oligotrophic bacterium was isolated from the biological soil crust underlayer in the Xinjiang Gurbantunggut Desert. It was numbered SGB-5, G . Cell size is (0.328-0.746) μm×(0.171-0.240) μm. Raised colony is white, roundness and its diameter is 5 mm. The strain is a facultative aerobe. It was able to grow in conditions of 1―15 mg·C·L?1 culture medium at 10―50℃. The strain's optimum growth temperature is 37℃. The range of its optimum growth pH is 8―9. A large amount of extracellular mucopolysaccharide was secreted during growth. The chemical composition of this mucopolysaccharide consists of arabinose, X sugar, glucose, galactose and mannitol. Mole ratio of these sugars is 1:14:19:6:14. The viscosity of the mucopolysaccharide can reach 6300 mPa·s, when the strain is cultivated for 72 h. After the culture solution in which viscosity was 1500 mPa·s was sprinkled on the quicksand surface, 6 mm bacteria crust of conglutinating sand was formed. This crust could not only stabilize sand, but could also potentially slow the rate of the soil water evaporation.