ALBERT

Description: Two revised seismic design codes in the Building Standard Law of Japan, which were revised in 1981 and 2000, are simply reviewed with the transition of Japanese seismic design code in this paper. The central feature of the seismic code revised in 1981 was the introduction of a two-phase earthquake design. Allowable stress design was employed for first-phase earthquake design targeting the safety and serviceability of buildings during medium-level earthquake activity. Second-phase earthquake design, which is ultimate strength design, was added to provide safety against severe earthquake motion. On the other hand, the seismic code revised in 2000 precisely defines performance requirements and verification based on accurate earthquake response and limit states of a building. The capacity spectrummethod is used for evaluating the earthquake response. The code is applicable to any type of material and buildings such as seismic isolation systems as long as material properties are well defined and structural behavior is appropriately estimated.

Description: At 8:50 (3:50 UTC) on October 8, 2005, a huge earthquake devastated Kashmir in Pakistan. Depth and magnitude were estimated 10 km and 7.6, respectively. The earthquake resulted from subduction of Indian plate beneath the Eurasian plate, and thrust faulting. Despite lack of no surface ruptures from as faulting, extensive slope failures occurred along the expected surface trace of the causative fault. Maximum ground acceleration for Balakot was estimated to exceed 0.9 g, based on overturned vehicles parallel to the valley axis. This probably represents the largest ground acceleration near the epicenter. Balakot is on the hangingwall side of the causative fault. One of the most distinct characteristics of 2005 Kashmir earthquake is the widespread slope failures all over the epicentral area. The earthquake extensively damaged housing and structures on sloping soil deposits. Extensive natural and cut-slope failures occurred along the Neelum, Jhelum and Kunhar valleys obstructing both river flow and roads. Many slope failures associated with highly sheared and weathered dolomitic limestone occurred along the presumed surface trace of the earthquake fault. Given the topography and possibility of slope failures, several alternative routes involving the construction of viaducts, tunnels and bridges are desirable in the area against road blockage by rock falls and slope failures.

Description: In prehistoric ages, mankind needed transportation but not transportation systems. In recent times, accompanying the development of human activities, the importance of transportation and transportation systems has increased more and more. By the word "transportation", the author means the spatial transfer of human beings, materials and articles and by the word "transportation system", he means a system of structures, facilities, and equipment effectively transferring human beings, materials and articles. So, highway systems, railway systems, air transportation systems, marine and river transportation systems, water supply and sewage systems and fuel and oil transportation systems are included as transportation systems.

Description: When structures are subjected to earthquake motions, the principal factors controlling their behavior are i) dynamic characteristics of the structure ii) characteristics of the input earthquake motions. In this sense, it is essential, first of all, to be acquainted with general dynamic properties. Let the simple structure – single degree of freedom system – as illustrated in Fig. 1 be considered. Spring, mass, and damper are the three elements which characterize the system. If to this system, an initial displacement is applied, then set it free, the time history of the displacement, velocity and acceleration will be as shown in Fig. 2. In Fig. 2 the basic concepts of period, frequency and circular frequency of the system are also explained.

Description: Tatsuo Usami, now professor emeritus at the University of Tokyo, published a paper entitled “Earthquake Studies and the Earthquake Prediction System in Japan” in the March 1974 issue of Technocrat. I was impressed by Professor Usami’s comprehensive review and healthy criticism of earthquake prediction in Japan, which appears fresh even today. He gave an overview of the 1923 Kanto earthquake and Program 1 to 2 of the earthquake prediction project in Japan. The motivation and research for the project in its early stage are well summarized in the paper. The Tokai earthquake hypothesis [1] was proposed during Program 3, so the budget for the project at national universities was approximately tripled in Program 4 and increased to about 12 billion yen in Program 7 (Table 1). The 1995 Kobe (Hyogo-ken Nanbu) earthquake occurred during Program 7 killing 6,434 people and completely destroying 104,906 houses [2]. Since this unexpected earthquake was as destructive as the 1923 Kanto earthquake, the earthquake prediction project was reformed in New Program 1 (Table 1). The Headquarters for Earthquake Research Promotion was established, moving emphasis from empirical short-term prediction to long-term earthquake forecasting and prediction of strong ground motion [3]. Dr. Hiroe Miyake and I reviewed this situation in a preceding article [4], taking over the mission of writing a recent history of Japanese seismology from Professor Usami's paper. References: [1] K. Ishibashi, “Did the rupture zone of the 1707 Hoei earthquake not extend to deep Suruga Bay?,” Rep. Subcomm. Tokai Distr., Coord. Comm. Earthq. Predict., Geogr. Surv. Inst., pp. 69-78, 1977 (in Japanese). [2] K. Koketsu, “Chronological table of damaging earthquakes in Japan,” in Chronological Scientific Tables 2007, Maruzen, pp.698-729, 2006 (in Japanese). [3] N. Hirata, “Past, current and future of Japanese national program for earthquake prediction research,” Earth Planets and Space, 56, pp. xliii-l, 2004. [4] K. Koketsu and H. Miyake, “Earthquake Observation and Strong Motion Seismology in Japan from 1975 to 2005,” Journal of Disaster Research, Vol.1, No.3, pp. 407-414, 2006. Kazuki Koketsu Professor, University of Tokyo

Description: This book is a work for general readers, straight-forwardly treating the theme of "strong earthquake ground motion" directly causing disaster and explaining how to cope. Eartquake ground motion is generally said to cause earthquake disasters and the degree of ground motion is determined both by the magnitude of the earthquake and the distance from its epicenter. In reality, however, things are not so simple. In the 2003 Tokachi Offshore Earthquake, for example, shaking at a relatively long 10-second period resonated at the characteristic frequency of oil tanks, triggering sloshing and causing large fires. In the 1995 Southern Hyogo Prefecture Earthquake (the Great Hanshin-Awaji Earthquake Disaster), for another example, a long narrow belt of disaster confirmed where damage to collapsed building was especially significant because only ground within this belt quaked more intensely than elsewhere.

Description: The mid-Java earthquake disaster of May 27, 2006, collapsed 139,859 houses and killed 5,778 people when their homes collapsed. Despite the dreadful damage, people began rebuilding houses similar to whose before the disaster. Once a house collapsed, people dug their household goods out of the debris, then sorted out anything reusable, such as bricks, tiles, beams, and RC column rebars for building new houses. This contrasts with Japan, where private houses destroyed by an earthquake would be thoroughly demolished and disposed of as debris, although household goods or property would be reused if possible. This difference between countries points out how circumstances driving the process of building, maintaining, and rebuilding houses drastically vary among nations and over time. New seismic-resistant housing must meet circumstances in ways different from existing housing, requiring much attention and effort to getting an overall picture of how the housing process in a target field is proceeding, what factors affect the process, and how all of these relate.

Description: In the preceding article, I reviewed two seismic design codes of the Building Standard Law of Japan, revised in 1981 and 2000, with the transition of Japanese seismic design codes. Having read the 1974 review by Dr. Makoto Watabe, I was most impressed by his comprehensive understanding of seismic structural systems for buildings – an understanding that is fresh even today, more than 3 decades later. He moves from the basic principles for seismic building design to earthquake-resistant properties of building. The general seismic design principles of buildings he has reviewed are very sound and introduced both in current seismic design codes I have reviewed and the seismic design of super high-rise buildings over 60 m high.

Description: We review earthquake observation and strong motion seismology in Japan over the three decades starting in 1975. Preceding the 1995 Kobe earthquake, earthquake prediction research programs played an important role in earthquake observation research. The devastating damage from this earthquake, however, forced a change in emphasis from empirical shortterm prediction to long-term forecasting of earthquakes and the prediction of strong ground motion. Nationwide observation networks were set up, and progress in strong motion seismology was applied to projects of national seismic hazard maps. The next disastrous earthquake may even force their reexamination in the near future.