Temporal and spatial variations in the discharge and dissolved organic carbon of drip waters in Beijing Shihua Cave,China

To detect the causal relationship between cave drip waters and stalagmite laminae, which have been used as a climate change proxy, three drip sites in Beijing Shihua Cave were monitored for discharge and dissolved organic carbon (DOC). Drip discharges and DOC were determined at 0 to 14‐day intervals over the period 2004–2006. Drip discharges show two types of response to surface precipitation variations: (1) a rapid response; and (2) a time‐lagged response. Intra‐annual variability in drip discharge is significantly higher than inter‐annual variability. The content of DOC in all drip waters varies inter‐ and intra‐annually and has good correlation with drip water discharge at the rapid response sites. High DOC was observed in July and August in the three years observed. The flushing of soil organic matter is dependent upon the intensity of rain events. The DOC content of drip water increases sharply above a threshold rainfall intensity (>50 mm d^?1) and shows several pulses corresponding with intense rain events (>25 mm d^?1). The DOC content was lower and less variable during the dry period than during the rainy period. The shape of DOC peak also varies from year to year as it is influenced by the intensity and frequency of rainfall. The different drip sites show marked differences in DOC response, which are dominated by hydrological behaviour linked to the recharge of the soil and karst micro‐fissure/porosity network. The results explain why not all stalagmite laminae are consistent with climate changes and suggest that the structure of the rainy season events could be preserved in speleothems. Copyright © 2008 John Wiley & Sons, Ltd.     

Dynamic characteristics and horizontal transports of internal solitons generated at the Columbia River plume front

River plume front-generated internal solitons play an important role in the interaction between the plume and coastal waters. The internal solitons drive a non-harmonic velocity field, resulting in a horizontal transport that carries plume water seaward and redistributes nutrients and sediments. In this study, we present observations of internal solitons generated at the Columbia River plume front that separates the new, tidal plume, older plume and coastal waters. Scale analyses suggest that the plume front-generated internal solitons are highly non-linear waves, and their dynamic properties do not conform to any weakly non-linear theory. Thus, a high-order Korteweg–de Vries (KdV) theory is used to analyze the internal solitons. The comparison between theoretical values and cruise data shows that the high-order KdV model is much better than the weakly non-linear theories for prediction of the soliton dynamic parameters. Based on the model, we develop theoretical and numerical solutions of the soliton-induced upper layer horizontal transport and Lagrangian water parcel transport distance, which shows that the water particle drift, during the internal soliton passage, is as far as 1 km, and demonstrates the role of the internal solitons on the exchange between the plume and ambient coastal water. Energy fluxes caused by the internal solitons are estimated using the high-order KdV theory. The leading soliton fluxes 2.0×10³ W m⁻¹ per unit crest length, and carries energy of 4.2×10⁵ J m⁻¹. The total energy carried by the eight internal solitons is 1.6×10⁶ J m⁻¹, about 70% of the total frontal energy.     

Seismic Damage Characteristics of the Wenchuan Great Earthquake on May 12,2008 and Suggestions for Disaster Prevention

The paper introduces the tectonic background,focal mechanism and distribution of aftershock of the Wenchuan earthquake on May 12,2008. The earthquake is considered to be the result of long-term interaction between the eastward movement of the Bayan Har Block and the Sichuan Basin. Most of the earthquake energy was released in an area (the seismic source body) 330km long,52km wide and 20km deep over 100s. Energy release in the source body was extremely uneven,and strong ground motion in the epicenter area shows obvious asymmetrical character in the time and space scale. The high-intensity area is distributed along the source body,and the intensity distribution bears an obvious anomalous characteristic. The investigation results indicate that more than 90 percent of casualties caused by this earthquake were in the areas of intensity IX or above. Houses,schools and hospitals etc. suffered serious damage. Lifelines such as transportation,water conservation etc. also suffered significant damage. Besides,earthquake-triggered avalanches,landslides,mud-rock flows and so on were extremely serious. The tremendous earthquake disaster highlighted the deficiencies in disaster prevention and mitigation management,scientific earthquake research,technology and application of earthquake disaster prevention,and publicity of earthquake preparedness and disaster reduction.     

Inversion of focal mechanism and events identification using an improved relative amplitude method

The relative amplitude method(RAM) is more suitable for source inversion of low magnitude earthquakes because it avoids the modeling of short-period waveforms.We introduced an improved relative amplitude method(IRAM) which is more robust in practical cases.The IRAM uses a certain function to quantify the fitness between the observed and the predicted relative amplitudes among direct P wave,surface reflected pP and sP waves for a given focal mechanism.Using the IRAM,we got the fault-plane solutions of two ea...     

Geochemical characteristics of soil gas in the Yanhuai basin,northern China

The geochemical backgrounds and origins of soil gases in the Yanhuai basin are discussed based on the regional seismogeological data and concentrations of Rn,Hg,CO2,H2,He and CH4 in soil gas measured at 422 investigating sites in field during September to October 2007.The geochemical background values of Rn,Hg,CO2,H2,He and CH4 are(8105.8±5937.4) Bq/m3,(9.7±5.8) ng/m3,(395.9±35.3)×10-6,(4.0±2.3)×10-6,(15.9±10.4)×10-6 and(12.7±8.1)×10-6,respectively.The geochemical backgrounds of the soil gases are higher in...     

天然气水合物矿体三维可视化及其Open Inventor实现

在天然气水合物的勘探开发过程中,三维水合物矿体模型的建立,可以定量地描述水合物储层的几何形态和地震属性参数的三维空间分布,并能进行水合物空间展布趋势的验证和预测.本文将Open Inventor三维图形软件包同Visual C++.NET绑定,作为开发工具,实现地震反演波阻抗数据矿体的三维雕刻动态显示、不同属性条件下的BSR曲面显示以及颜色表插值处理等功能.     

2D多尺度混合优化地球物理反演方法及其应用(英文)

局部优化和全局优化方法广泛应用到地球物理反演,但是两者各有其优缺点。将两类方法结合起来可以取长补短。将退火遗传算法（SAGA）和单纯形算法相结合,得到了一种高效、健全的2D非线性混合地震走时反演方法。首先,利用SAGA进行大范围的全局搜索,然后由单纯形方法进行快速局部搜索。为了降低层析成像的多解性,我们采用了多尺度逐次逼近的技巧。把速度场划分为不同的空间尺度,定义网格节点上的速度作为待反演参数,采用双三次样条函数模型参数化,正问题采用有限差分走时计算方法,反问题采用多尺度混合反演方法。一个低速度异常体的数值模拟试验和抗走时扰动试验表明该方法是有效和健全的。我们将该方法应用到青藏高原东北缘阿尼玛卿rlet,Meyer,Marr,缝合带东段上部地壳速度结构研究中。数字模型试验和实际资料的应用表明了方法的有效性和健全性。     

基于GDW的空间数据融合

空间数据融合是目前地学信息领域面临的难题。通过介绍Oracle数据仓库系统架构和其在地学信息存储和分析方面的优点,深入分析ArcInfo中的Geodatabase的空间数据组织模型,重点研究了Oracle Spatial的空间数据存储模型、空间数据和空间索引组织模式,并给出了空间数据融合的具体实现过程。针对具体项目,结合GIS二次开发,能非常高效地实现空间数据的融合。     

夏季欧亚阻塞高压逐日演变的定量化分析

利用NCEP/NCAR 1998-06～1998-08逐日500 hPa高度场资料,对夏季欧亚阻塞高压的逐日演变作了定量化研究.结果发现,利用纬偏值作为基本量可以计算出乌拉尔山地区(25～80°E)、贝加尔湖地区(80～125°E)、鄂霍茨克海地区(125～170°E)3个区域阻塞高压的面积指数,该特征值能很好地揭示1998年夏季阻塞高压强度和位置变化的逐日演变特征,并且与我国1998年夏季降水的分布有重要的联系.     

A Preliminary Interpretation of Near-field Observation Data of the Zhangbei Earthquake

In this paper, a preliminary data processing was made for tbe aftershock records or theZhangbei M6.2 earthquake on Jan. 10, 1998. The hypocenters of 205 earthquakes with M_L≥0.5 were located. The result shows that most aftershockS were concentrated in a more than10 km long and 5～8 km wide NE-trending beIt. The source mechanism solutions of largeraftersbocks were also calculated, from which it can be inferred that the faulted zone of themain shock is an NE-trending fault. Furthermore, the spectral analysis of P waves was made.The corner frequency is about 10 Hz.