Earthquake Hazard Mitigation in the New Madrid Seismic Zone: Science and Public Policy

In the central United States, earthquake sources that are not well defined, long earthquake recurrence intervals, and uncertain ground-motion attenuation models have contributed to an overstatement of seismic hazard for the New Madrid Seismic Zone on the national seismic hazard maps published by the U.S. Geological Survey. A series of informal interviews in western Kentucky with local businesspersons, public officials, and other professionals in occupations associated with seismic-hazard mitigation discussed seismic-mitigation policies in relation to depressed local economy. Scientific and relative economic analysis was then performed using scenario earthquake models developed with the Federal Emergency management Agency\u27s Hazus-MH software. The ground-motion hazard generated by the 2008 Wenchuan, China, earthquake and seismic mitigation policies in that area were compared with those of the New Madrid Seismic Zone. Continued scientific research, additional educational opportunities for laymen and engineering professionals, and changes in the application of current earthquake science to public policy in the central United States should help improve public safety and economic development

The Geotechnical Hazard Induced by 8.1 Earthquake in West Pass of Kunlun Mountatin in China in 2001

On November 14, 2001, a great earthquake with a magnitude of Ms=8.1 occurred in the Qinhai-Tibet Plateau, China, which is called as the west pass of Kunlun mountain Ms8.1 earthquake. This earthquake is the largest and the first one with a magnitude greater than 8.0 in mainland China in the recent 50 years. It caused a large-scale deformation zone with a length of 426 km in frozen soil deposit in the plateau with a height of 4000-5500 meters above sea level. Some geotechnical hazards induced in the meizoseismal area, such as compression and tension failure of soil deposit, shaking landslides (collapse of slope and cliff), seismic settlement, sliding of glacier and snow. Unexpectedly, liquefaction occurred within the melting sand layer in frozen soil deposit on the banks of lakes and rivers. All the hazards were investigated in the field by the authors. This paper presents the results of the field investigation and tests made

Criterions, Prediction and Prevention of Loess Liquefaction

Although loess liquefaction is not very common during earthquakes in Northwest of China, it is disastrous if it happens. Both study and valid evidence from Haiyuan 8.5 Earthquake in 1920 and Tajikistan 5.9 Earthquake in 1989 have proved that loess liquefaction could be very disastrous under certain conditions. In this paper, the criterions of loess liquefaction are discussed to show that unlike typical liquefaction of sand, loess which falls into the category of both silt clay and clayey silt has unique characteristics during liquefaction test. To predict liquefaction of loess, a simple method based on laboratory test and field evidences using GIS is proposed. The prediction results and corresponding measure have been adopted in Seismic Design Code for Buildings in Lanzhou Urban Area. Finally, recent approach of treatment of loess with chemicals methods is developed, which may have some application implication as an simple and feasible treatment method against liquefaction of loess

Qinghai-Tibet Railway, China and the Solutions to Its Major Geotechnical Problems for Construction

The Qinghai-Tibet Railway (QTR) is the highest-elevation one for passenger trains in the world and the first railway to connect central China to Tibet. Construction of this railway starting in 2001 had to contend with major geotechnical challenges, such as permafrost, environmental protection and seismic hazards. Its completion in 2006 is a remarkable feat in the world’s railway construction history and crystallization of wisdom of human beings. In this paper, the planning and preparing history and the construction project of QTR are introduced. The major three thorny problems, permafrost, lack of oxygen and environmental frangibility for the construction and their solutions are presented, which are active methods of riprap roadbeds, heat pipe roadbed and bridges over land for permafrost, health care system for lack of oxygen and environmental protection measures for construction and operation. Seismic safety assessment was carried out for earthquake damage mitigation of the railway. The laboratory test, field test and observation, and it’s operation have shown that design, construction, and measures for earthquake hazards mitigation and environmental protection of the Qinghai-Tibet Railway are completely successful

Comparison of Liquefaction Potential of Loess in China, USA, and Russia

Loess is extensively distributed in many parts of the world, including China, the United State and Russia. Based on experimental study of loess obtained from the three countries, the liquefaction potential of loess are investigated. It is found though loess in the three country all have liquefaction potential, their peak ground acceleration of triggering liquefaction and their behavior during liquefaction vary significantly. Further study of microstructure of loess reveals that the microstructure of the loess in the three countries differs each other in many ways. This factor, combined with the different of gradation, physical index and formation materials, accounts for the different liquefaction behavior of loess in the three countries. Under no circumstance, however, should the liquefaction problem of loess be ignored for its dangerous effects caused by great amount of residual strain during liquefaction

Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui