Study of calibration function for surface wave magnitude of DK1 seismographs

ＳｔｕｄｙｏｆｃａｌｉｂｒａｔｉｏｎｆｕｎｃｔｉｏｎｆｏｒｓｕｒｆａｃｅｗａｖｅｍａｇｎｉｔｕｄｅｏｆＤＫ１ｓｅｉｓｍｏｇｒａｐｈｓＦＥＮＧＸＵＥ（薛峰）ＹＯＮＧＺＨＡＯ（赵永）ＣｅｎｔｅｒｆｏｒＡｎａｌｙｓｉｓａｎｄＰｒｅｄｉｃｔｉｏｎ，Ｓｔａｔ...     

用复曲线拟合方法确定DD-1和DK-1型电子放大地震仪的传递函数、频率特性和时间特性

地震仪的动力学特性通常是用频率域中的幅频特性和相频特性表示的,但是,合成地震图和由地震图恢复地面的真实运动都是在时间域中进行的,这就需要知道地震仪的时间特性（脉冲响应特性）。从理论上讲,可以由实测地震仪的幅频与相频特性通过快速傅里叶变换（FFT）用数值方法把时间特性计算出来,但是,计算结果表明,误差很大,尤其是在初动部分。因此,计算地震仪的时间特性应该从地震仪的传递函数出发,通过拉普拉斯反变换求得。 目前,我国基准地震台上使用三种类型地震仪:直接耦合地震仪、电流计记录地震仪和电子放大地震仪。前两种地震仪,它们的运动方程和传递函数已知,传递函数系数可以通过经典的分段标定方法求得。但是,对于电子放大地震仪,由于引入电子线路,首先必须确定电子线路部分的传递函数及其系数,然后再求出它们的频率特性和时间特性的解析表达式。 作者根据DD-1和DK-1型电子放大地震仪的分段标定结果,用复曲线拟合方法求出了它们的传递函数,并由传递函数导出了频率特性和时间特性的解析表达式,计算出了DD-1和DK-1型地震仪的幅频特性曲线、相频特性曲线和时间特性曲线。     

Application of possibility-probability distribution in assessing water resource risk in Yiwu city

The possibility-probability risk calculated using the interior-outer set model is referred to as fuzzy risk. A fuzzy expected value of the possibility-probability distribution is a set with E _α(x) and [`(E)]<sub>a</sub>\bar E_\alpha (x) as its boundaries. The fuzzy expected values E <sub>α</sub>(x) and [`(E)]_a\bar E_\alpha (x) of a possibility-probability distribution represent the fuzzy risk values being calculated. Under such an α level, three risk values can be calculated: conservative risk value, venture risk value and maximum probability risk value. As α adopts all values throughout the set [0, 1], it is possible to obtain a series of risk values. Therefore, the fuzzy risk can be a multi-valued risk or set-valued risk. Calculation of the fuzzy expected value of Yiwu city’s water resource risk has been performed based on the interior-outer set model. We can get a conservative risk value (R _C ) of 800 mm for Yiwu city’s water resource risk, a venture risk value (R _V ) of 1020 mm, and a maximum probability risk value (R _M ) of 988 mm for the α = 0.1 level cut set.     

A NEW PARAMETER FOR THE INTERPRETATION OF INDUCED POLARIZATION FIELD PROSPECTING (time-domain) *

In a previous paper it has been shown that we can relate the transient IP electric field E_p , existing in a rock after a step wave of polarizing current, with the steady-state current density J_ss during the current step wave as follows: E_p =ρ' J_ss . This relation may be interpreted as a generalized Ohm's law, valid in linear cases, in which ρ’(fictitious resistivity) is defined as the product of the true resistivity ρ with the chargeability m. Supposing E _p=— grad U_p and applying the divergence condition div J_ss = o, one can, for a layered earth, obtain a general expression for the depolarization potential U_p as a solution of Laplace's equation ?²U_p= o. Since the mathematical procedure for the solution of this last equation is identical to that used in resistivity problems, we propose now the introduction of an apparent fictitious resistivity ρ'_a (defined as the product of the apparent resistivity ρ_a with the apparent chargeability m_a) as a new parameter for the interpretations of IP soundings carried out over layered structures with a common electrode array. The most general expression of ρ'_a as a function of the electrode distance turns out to be mathematically identical to the general expression of ρ'_a. Therefore it is possible to interpret a ρ'_a field curve using the same standard graphs for resistivity prospecting with the usual method of complete curve matching. In this manner a great deal of work is saved since there is no need to construct proper m_a graphs for the interpretation of IP soundings, as it has been done up to now. Finally some field examples are reported.     

Signal and noise coherence determination for the Uppsala seismograph array station

Summary The Uppsala seismograph array station (UPSAS) has been tested with respect to mutual resemblance of body-wave signals recorded by the individual array sensors. Records ofP-, pP- andPKP-phases from ten teleseismic earthquakes and the HANDLEY explosion, in the magnitude range fromm _b =5.8 tom _b =6.9, are investigated in detail. Calculated coherence and cross-correlation functions confirm that the area selected for UPSAS provides extremely favourable conditions for the operation of an array station. High signal similarity across UPSAS shows no obvious dependence upon the location of the focus or the magnitude. Natural and man-made events provide comparable results.     

数字化地震仪系统的标定

介绍了数字地震仪系统传递函数的特征和测定方法,给出了地震仪标定软件的使用方法和计算步骤。结合实际波形数据处理过程,着重对标定计算中参数的设置,以及需要注意的问题进行了讨论和分析。这对于正确快速地获取地震仪的传递函数具有重要的现实意义,有利于国家数字地震台站和区域地震台站地震观测系统的定期标定工作,同时也将促进数字化地震观测资料的应用研究。     

Uptake and depuration of PAHs and chlorinated pesticides by semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis)

Semi-batch seawater experiments were conducted to follow the uptake and release of selected PAHs (anthracene, fluorathene, pyrene and B[a]P) and organochlorine pesticides (α-HCH, aldrin, dieldrin, p,p′-DDT) in semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis). Mathematical models were applied to describe the uptake and elimination curves of the contaminants for SPMDs, and kinetic parameters, such as uptake rate constants, and equilibrium triolein/water partitioning coefficients were calculated. SPMD data showed a good fit to estimate rate constant and partition coefficient equations, but only those contaminants which partitioned mainly in the dissolved phase (α-HCH and dieldrin) were well explained for mussels. Poor conformity of the other contaminants indicated mussels uptake by routes other than diffusion, such as ingestion of algae. An apparent equilibrium state was only noted for α-HCH in mussels. Aldrin was not detected in mussels in the first few days of exposure, indicating potential metabolism of this compound. B[a]P was not detected in the triolein of SPMDs, which suggests that the membrane may act as a reservoir. Loss of spiked B[a]P from the triolein was evident in a depuration experiment, which may indicate transfer to the membrane. Rate constants for mussels were higher than those for SPMDs, but the reverse was true for partition coefficients. Overall, mussels and SPMDs had similar uptake rates for all compounds in this study, excluding p,p′-DDT and dieldrin. Contaminant elimination took place more rapidly in mussels, implying that SPMDs are better candidates for detecting episodic discharge of organic contaminants.     

Relationship between the common climatic parameters and average drought frequency

The parameters commonly considered to define climate are the mean annual precipitation and mean annual potential evapotranspiration. In this study an attempt has been made to develop a relationship between average drought frequency and the evapotranspiration/precipitation ratio for the arid, semi‐arid and subhumid climatic regions of India. The climatic regions are delineated using two climatic indices: namely (i) the ratio of mean annual precipitation (P_a) to global terrestrial mean annual precipitation (P_g), and (ii) the ratio of mean annual potential evapotranspiration (E_p) to mean annual precipitation (P_a). It was noted that the average drought frequency (i e., year^?1.) decreases gradually from dry to wet regions. The return period varies from 2 to 3 years in the arid regions (12>E_p&sol;P_a≥5), 3 to 5 years in semi‐arid regions (5>E_p&sol;P_a≥2), and 5 to 8 years in sub‐humid regions (2>E_p&sol;P_a≥3&sol;4). Another relationship was developed between the average frequency of drought occurrence and the ratio of mean annual deficit to mean annual precipitation, (E_p?P_a)&sol;P_a. The results have been compared with the drought experiences documented for other regions of the world. Copyright © 2001 John Wiley & Sons, Ltd.     

剪切波分裂分析系统SAM(2007)——软件系统

地震各向异性是一种普遍现象,利用剪切波分裂可以研究地壳介质的地震各向异性特性,这是地震学研究中的一个前沿课题。本文介绍了基于SAM(2003R)发展的剪切波分裂系统分析方法软件——SAM(2007)。SAM(2007)在保留原软件系统优点的基础上,修改和发展了新的功能,在资料预处理、数据分析和结果输出等方面都进行了更新或发展,增加了地震定位模块,使新的软件系统更适用于国内的区域地震台网或流动台网资料的处理和分析。     

Using neural networks for calibration of time-domain reflectometry measurements

Abstract

Time-domain reflectometry (TDR) is an electromagnetic technique for measurements of water and solute transport in soils. The relationship between the TDR-measured dielectric constant (K_a ) and bulk soil electrical conductivity ([sgrave]_a) to water content (θ_W) and solute concentration is difficult to describe physically due to the complex dielectric response of wet soil. This has led to the development of mostly empirical calibration models. In the present study, artificial neural networks (ANNs) are utilized for calculations of θ_w and soil solution electrical conductivity ([sgrave]_w) from TDR-measured K_a and [sgrave]_a in sand. The ANN model performance is compared to other existing models. The results show that the ANN performs consistently better than all other models, suggesting the suitability of ANNs for accurate TDR calibrations.     

The relationship between seismic velocity and radioactive heat production in crustal rocks: An exponential law

In crystalline rocks seismic velocityV _p and densityp increase, whereas radioactive heat productionA decreases from acidic to basic compositions. From the velocity-density systematics for crustal rocks at different pressures an empiricalA(V _p) relationship has been derived for the range 5.0–8.0 km/sec which follows the exponential law:A(V _p )=a exp (-bV _p ), where the numerical factorsa andb depend onin situ pressure. A graph is given by means of which the heat production distributionA(z) can be obtained for any givenV _p (z) structure.Contribution No. 207, Institute of Geophysics, ETH Zurich.     

Development of an aftershock occurrence model calibrated for Turkey and the resulting likelihoods

This paper presents the calibration of Omori's aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock that exceeds a specific magnitude threshold within a time interval after the mainshock. Critical decisions on the post-earthquake safety of structures directly depend on the aftershock hazard estimated using the occurrence model. It is customary to calibrate models in a region-specific manner. These models depend on rate parameters(a, b, c and p) related to the seismicity characteristics of the investigated region. In this study, the available well-recorded aftershock sequences for a set of Mw ≥ 5.9 mainshock events that were observed in Turkey until 2012 are considered to develop the aftershock occurrence model. Mean estimates of the model parameters identified for Turkey are a =-1.90, b = 1.11, c = 0.05 and p = 1.20. Based on the developed model, aftershock likelihoods are computed for a range of different time intervals and mainshock magnitudes. Also, the sensitivity of aftershock probabilities to the model parameters is investigated. Aftershock occurrence probabilities estimated using the model are expected to be useful for post-earthquake safety evaluations in Turkey.     

Application of the method of dynamic calibration for IMS stations in regions with lower seismic activity

The Method of Dynamic Calibration (MDC) of stations of the International Monitoring System (IMS) was developed for calibrating regions where no underground nuclear explosions were carried out, with the purpose of providing conditions for implementation of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in nontrivial cases. Initially, the MDC had been presented in [Kedrov, 2001; Kedrov et al., 2001; Kedrov O.K. and Kedrov E.O., 2003] and then considered in detail in [Kedrov et al., 2008]. The core of MDC relates to adapting diagnostic parameters for the identification of underground nuclear explosions (UNE) and earthquakes elaborated for the region of Eurasia, taken as a basic region (BR), for other researched regions that differ from BR in the character of the attenuation of seismic waves. The unique characteristic of this method lies in the fact that calibration of diagnostic parameters with the help of attenuation coefficients b _Δ at varied source-station traces is implemented using only natural seismicity data within the limits of an explored region and does not require special underground chemical explosions. The MDC algorithm is implemented in the research program ”Kalibr”, which was tested by using the experimental data from Eurasia region. It is shown in this work that MDC can be used for calibration of regions where a very low level of natural seismicity is observed. According to the results of the calibration of diagnostic parameters at IMS stations in several regions of North America, Africa, and Asia, the approximate classification of propagation conditions for seismic signals at source-station traces in platform and tectonically active regions is made. The results for the development of two research programs, “Spektr” and “Signal”, are presented; this software is intended for automation of calculation procedures for spectral diagnostic parameters of UNEs’ and earthquakes’ identification by amplitude spectra of P waves and by the maximal amplitudes of P, S, and LR signals. The application of these programs allowed us to accelerate the whole calibration procedure for a particular source-station trace using the ”Kalibr” program.     

Pan evaporation modelling and changing attribution analysis on the Tibetan Plateau (1970–2012)

Pan evaporation (E_p) is an important indicator of water and energy and the decline of E_p has been reported in many regions over the last decades. The climate and E_p are dependent on each other. In this study, the temporal trends of E_p and main E_p drivers, namely mean air temperature (T_a), wind speed (u), global solar radiation (R_s), net long‐wave radiation(R_nl) and vapour pressure deficit (D) from 1970 to 2012, were calculated on the basis of 26 meteorological stations on the Tibetan Plateau. The arithmetic average of E_p from 26 stations decreased with the rate of ?11.91 mm a^?2; the trends of R_s, R_nl, T_a, u and D were ?1.434 w m^?2 decade^?1, 0.2511 w m^?2 decade^?1, 0.3590°C decade^?1, ?0.2376 m s^?1 decade^?1 and 9.523 Pa decade^?1, respectively. The diffuse irradiance is an essential parameter to model E_p and quantify the contribution of climatic factors to changing E_p. 60 724 observations of R_s and diffuse solar irradiance (R_d) from seven of the 26 stations were used to develop the correlation between the diffuse fraction (R_d/R_s), and the clearness index (R_s/R_o). On the basis of the estimation of the diffuse component of R_s and climatic data, we modified the PenPan model to estimate Chinese micro‐pan evaporation (E_p) and assess the attribution of E_p dynamics using partial derivatives. The results showed that there was a good agreement between the observed and calculated daily E_p values. The observed decrease in E_p was mostly due to declining wind speed (?13.7 mm a^?2) with some contributions from decreasing solar irradiance (?3.1 mm a^?2); and the increase of temperature had a large positive effect (4.55 mm a^?2) in total whilst the increase of R_nl had insignificant effect (0.35 mm a^?2) on E_p rates. The change of E_p is the net result of all the climatic variables. Copyright © 2014 John Wiley & Sons, Ltd.     

APPROXIMATE INVERSION OF AIRBORNE EM DATA FROM A MULTILAYERED GROUND1

A complex transfer function c (or generalized skin depth) can be derived from data for the secondary magnetic field measured by a dipole system with small coil spacing at height h above the ground. This function has a useful property: For a uniform or layered ground, the real part of c yields the‘ centroid depth’z* of the in-phase current system as a function of frequency. This parameter can be combined with the apparent resistivity ρ_a derived by conventional methods. The function ρ_a(z*), if known over a broad frequency range, yields a smoothed approximation of the true distribution ρ(z) without an initial model. The relations between ρ_a(z*) and ρ(z) are studied for a number of multilayer models. An example of the application of the ρ_a*) algorithm to data from a groundwater survey is given.     

Sensitivity and uncertainty analysis of mesoscale model downscaled hydro‐meteorological variables for discharge prediction

Precipitation and Reference Evapotranspiration (ETo) are the most important variables for rainfall–runoff modelling. However, it is not always possible to get access to them from ground‐based measurements, particularly in ungauged catchments. This study explores the performance of rainfall and ETo data from the global European Centre for Medium Range Weather Forecasts (ECMWF) ERA interim reanalysis data for the discharge prediction. The Weather Research and Forecasting (WRF) mesoscale model coupled with the NOAH Land Surface Model is used for the retrieval of hydro‐meteorological variables by downscaling ECMWF datasets. The conceptual Probability Distribution Model (PDM) is chosen for this study for the discharge prediction. The input data and model parameter sensitivity analysis and uncertainty estimations are taken into account for the PDM calibration and prediction in the case study catchment in England following the Generalized Likelihood Uncertainty Estimation approach. The goodness of calibration and prediction uncertainty is judged on the basis of the p‐factor (observations bracketed by the prediction uncertainty) and the r‐factor (achievement of small uncertainty band). The overall analysis suggests that the uncertainty estimates using WRF downscaled ETo have slightly smaller p and r values (p= 0.65; r= 0.58) as compared to ground‐based observation datasets (p= 0.71; r= 0.65) during the validation and hence promising for discharge prediction. On the contrary, WRF precipitation has the worst performance, and further research is needed for its improvement (p= 0.04; r= 0.10). Copyright © 2013 John Wiley & Sons, Ltd.     

Secular and seasonal changes in transfer function at Guangzhou geomagnetic observatory

Time changes in transfer functions of short period geomagnetic variations in 28 years from 1960 through 1987 are studied, systemically and in detail in this paper. The results indicate that: (1) It is evident that seasonal and secular changes in the transfer functionsA at exist the Guangzhou Geomagnetic observatory. The characteristics for seasonal changes are large in summer and smaller in winter with main cycles of 12 and 6 months. The characteristic for secular change is a descend with a rate of 0.0025 per year. The seasonal and secular changes in transfer functionsB are not evident. (2) The direction of Parkinson vector at Guangzhou geomagnetic observatory is clearly affected by the ocean, and is associated with coastal effect. (3) The values of the transfer function A and B are related to geomagnetic activity ata=0.05. Secular change is not related to geomagnetic activity, maybe it is affected in a great measure by earth conductivity change. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica sinica,13, 480–488, 1991. This study is part supported by Chinese Joint Seismological Science Fundation.     

Effect of peak ground acceleration to velocity ratio on ductility demand of inelastic systems

A statistical analysis is performed to investigate the significance of peak ground acceleration to velocity ratio (a/v) on the displacement ductility demand of simple bilinear hysteretic systems. Three groups of earthquake records representative of low, normal and high<a/v ranges are used as input ground motions. The design yield strength of the inelastic systems is specified from the base shear formula in the 1980 National Building Code of Canada (NBCC 1980) and that in NBCC 1985 respectively. The former case represents the common practice of specifying seismic design base shear based on a peak site acceleration, while in the latter case the base shear is specified based on peak ground velocity and a/v ratio. Mean displacement ductility demands are obtained for the three groups of ground motions; and the corresponding dispersion characteristics are examined. The results show that the ground motion<a/v range has a significant effect on the displacement ductility demand, and it should be accounted for in design strength specification.     

Trends in land surface evapotranspiration across China with remotely sensed NDVI and climatological data for 1981–2010

Abstract

Using satellite observations of Normalized Difference Vegetation Index (NDVI) from NOAA-AVHRR and Terra-MODIS, together with climatic data in a physical evapotranspiration (ET) model, the spatio-temporal variability of ET is investigated in terrestrial China from 1981 to 2010. The model predictions of actual ET (ET_a) are validated with ET values from in situ eddy covariance flux measurements and from basin water balance calculations. The national averaged crop reference ET (ET_p) and ET_a values are 916 ± 21 and 415 ± 12 mm year^-1, respectively. The annual ET_a pattern is closely associated with vegetation conditions in the eastern part of China, whereas ET_a is low in the sparsely-vegetated areas and deserts in the northwestern region, corresponding to scarce rainfall events and amounts. The trends of ET_p and ET_a are remarkably different over the country, and the complementary relationship between ET_p and ET_a is revealed for the study period. Averaged over the whole country, ET_a showed an increasing trend from the 1980s to the mid-1990s, followed by a decreasing trend, consistent with the precipitation anomaly. Across the main vegetation types, annual ET_a amounts are found to correspond clearly with the bands of precipitation and ET_p.     

A method for calculating the transfer function of digital seismograph system

With the development of science and technology, the digital seismograph system has been adopted in largequantities for earthquake observation in China in recent years, which will replace gradually the original analogseismograph system. This is a big leap in the earthquake observation. The digital seismograph system make it pos-sible for us to perform fast great earthquake reports, obtain more information from earthquake records, whichcomes from the Earth interior media and the source process, and carry out further the researches on seismic sci-ence.……