Interpretive Pitfalls in Historical Hazards Data

The primary use of the natural hazards data archived at the National Geophysical Data Center (NGDC) and co-located World Data Center for Solid Earth Geophysics (WDC for SEG) is for the mitigation of future disasters. Among the responsibilities of NGDC/WDC for SEG is archiving and disseminating hazards data to city planners, educators, engineers and others engaged in mitigation efforts (approximately 150,000 users per week on our web site). Therefore, it is the purpose of this paper to educate the hazards' community about some of the limitations of these data. It is hoped that enlightened users would have a greater appreciation of data errors and possible sources of misinterpretation of the data.Personnel at NGDC/WDC for SEG are in a unique position to discuss the limitations of hazards data since we compile data from original and secondary sources. We are also in direct contact with the data users and know the applications that they make of hazard data, and the misjudgments that often occur when data limitations are not known.Most hazard catalogs cover periods of less than 200 years and are reasonably complete and accurate for only the past 20 to 50 years. Such catalogs are not sufficient to investigate long term hazard variations. Earthquake, tsunami, and volcano data catalogs, acquired and integrated at NGDC/WDC for SEG, illustrate artificial long-term variations created by cultural and scientific reporting changes, which can introduce unanticipated non-random variations into the catalogs. Inconsistencies are often related to changes in the way magnitudes are calculated, evolving network equipment, and network discontinuities of operation and personnel, among other error sources.Before statistical hazard studies can be done, catalogs need to be clearly understood to identify systematic patterns of an observational nature.     

南疆地区历史时期气候与环境演化

通过塔克拉玛干沙漠南缘具有较高的分辨率的尼雅剖面记录多指标的综合研究，结合南疆地区其他地质记录和历史资料，恢复了南疆历史时期（近4000年）以来气候与环境演化的特征与序列，共划分出3个相对冷湿期和3个相对暖干期，结果表明，此地区气候环境的演化在冷暖变化序列上基本吻合于我国东部地区，而在干湿波动上则具较为显著的西风型环境演变特征，同时还发现，南疆地区历史时期人类活动与气候环境演化之间存在非常密切的关系。     

文物旅游资源开发理念和实践初探

通过对洛阳文物旅游资源的分析 ,探讨文物旅游资源的三个基本特征及开发理念 ,并提出了具体的开发对策。     

Historical climate changes in southern Xinjiang

1 Introduction Southern Xinjiang has experienced tremendous changes in climate and eco-environment during historic times, for example, the rise and decline of oases and ancient towns, shrinkages and enlargement of lakes and changes in river system, etc. (Figure 1). All these can be attributable to the natural changes of climate and environment superimposed by human impacts. So, it is interesting and significant to reveal the inter-relation between natural climate changes and human抯 impact …     

阿克苏地区旅游资源及其开发利用

阿克苏地区位于丝绸之路北道中心地段，旅游资源丰富多彩，特色性强，共有景点126个，其中一二级景点37个，人文旅游资源占优势。根据资源的分布和类型特征，地缘优势及客源市场现状，确立了以丝绸之路北道辉煌灿烂的文物古迹和托木尔峰自然旅游资源区为核心，突出石窟文化艺术体系，围绕干旱区典型的自然风光和丰富多彩的民俗同情，提出了十一个重点旅游区的分期开发利用方向。     

Rapid evaluation of an indicator of seismic vulnerability in small urban nuclei

The expected fraction of buildings lost in the event of an earthquake of a given intensity can be considered as a useful indicator of the seismic vulnerability of a small urban nucleus and can be used for the evaluation of seismic risk on a regional scale. This work describes a procedure for quantifying this indicator through data obtained from the buildings which constitute the nucleus during rapid on-site surveys. The knowledge on which the procedure is based is that given by the observed vulnerability of old Italian centres.     

Estimating the vulnerability and loss functions of residential buildings

This paper is concerned with an investigation of the damage to residential buildings in two areas within Gilan and Zanjan provinces, Iran, caused by the Manjil-Rudbar earthquake of 20 June 1990. A statistical correlation between the observed ground motion and the damage to the residential buildings is derived for overall damaged buildings and expressed as the vulnerability function. The loss function is calculated by combining the seismic hazard with the vulnerability function.The study of vulnerability and annual seismic hazard shows that the specific annual risk for the range of motion of 0.18 to 0.5 g is equal to 0.02. This indicates that the specific risk for semi-engineered residential buildings with a lifetime of 20 years is about 33%. This study also shows that in large cities, such as Tehran, located in seismic areas, the extent of damage according to the vulnerability function will be 45 and 70% for expected maximum accelerations of 0.3 and 0.4 g, respectively.     

Re-evaluation of minor events: The examples of the 1895 and 1909 Rome earthquakes

The city of Rome is subjected to moderate seismic risk due to both local and external seismicity. Up to now, the maximum intensity felt has never exceeded VIII MCS. The 1 November 1895 (I _o = VII) and 31 August 1909 (I _o = VI) earthquakes demonstrate that small local events can also cause damage in a large old city. In the present work, we have re-evaluated the intensity values of those two events by means of automatic processing. A comparison between the present results with geological evidence and previous studies is shown, especially for the historical centre of Rome. For the first time, the 1909 earthquake instrumental magnitudeM _L = 3.6 has been calculated from original recordings.     

一个历史关系数据库管理系统——HXDB

历史关系数据库管理系统HXDB 是在关系数据库管理系统XDB 基础上扩充的,它在提供查询历史数据机制的同时,保证对当前数据的快速查找及最大限度地减少数据冗余。     

Intraplate seismicity of the Pacific Basin, 1913–1988

We establish here a comprehensive database of intraplate seismicity in the Pacific Basin. Relocation and analysis of 894 earthquakes yield 403 reliable intraplate earthquakes during 1913–1988. These numbers do not include earthquake swarms, which account for another 838 events. Most of the remainder (304 events) are actually plate boundary earthquakes that have been erroneously located in intraplate regions. A significant number occur in recent years when location capabilities should have guarded against this situation. Relocations involve a careful linear inversion ofP andS arrivals, accompanied by a Monte Carlo statistical analysis. We have also attentively removed the high number of clerical errors and nuclear tests that exist in epicenter bulletins.A geographical examination of the relocated epicenters reveals several striking features. There are three NW-SE lineaments north of the Fiji Plateau and in Micronesia; diffuse seismicity and incompatible focal mechanisms argue against the southernmost, discussed byOkal et al. (1986) andKroenke andWalker (1986), as the simple relocation of the Solomon trench to the North. Besides another striking lineament, along the 130°W meridian, there is also a strong correlation between seismicity and bathymetry in certain parts of the Basin. In the Eastcentral Pacific and Nazca plates there are many epicenters on fracture zones and fossil spreading ridges, and hot spot traces like the Louisville, Nazca and Cocos Ridges also display seismicity.