Future Seismic Events Research Articles

Lessons from the Kobe earthquake

Abstract The Kobe earthquake is considered to be one of the most devastating and costly natural disasters in recent history considering the number of buildings destroyed, the number of people killed and injured, the size of the affected area, and the extent and severity of damage to a wide range of structural types. As a result, important questions have been raised about earthquake preparedness, disaster response, seismic design and codes of practice, and upgrading of earthquake-resistant structures. This paper presents an overview of this earthquake, investigates the extent and types of damage caused, studies the factors behind each type of damage, and highlights important lessons learnt from this earthquake. Protective measures and future research that should be undertaken in Japan, and all countries that are at seismic risk, are recommended in order to reduce damage and casualties in future seismic events.

Observed and predicted earthquake response of La Villita Dam

La Villita earth and rockfill dam in Mexico has been subjected to five major earthquakes during the period 1975–1985. The recorded time histories of crest acceleration and associated permanent displacements imply the occurrence of seismically induced localized stick-slip slope deformations. In this paper, the upstream-downstream seismic response of La Villita dam is investigated in detail. The dam vibration characteristics are represented by a one-dimensional shear-wedge elasto-plastic numerical model. Available bedrock acceleration histories are employed as input excitation and seismic response is calculated using a step-by-step time integration procedure. Crest acceleration histories are computed and further employed to predict the observed permanent displacements. For that purpose, an elastic-perfectly plastic single-degree-of-freedom (SDOF) model is used in a Newmark-type sliding mass analysis. The predicted SDOF permanent displacements are found to be similar to their recorded counterparts. Moreover, this yielding SDOF model is found to capture the peculiar asymmetric response characteristics associated with the evolution of stick-slip displacements, and observed in the recorded crest accelerations of La Villita Dam. Finally, the employed numerical procedures are found to demonstrate the possible development of additional permanent crest displacements during future seismic events.

Parametric modeling of earthquake response spectra

A mathematical model for the response spectra is determined using statistical analysis. The form of the model is first established using fifty computer simulated accelerograms. The final form is then used on twenty-five accelerograms from fifteen past United States earthquakes. This model smooths out peaks and valleys which are characteristic of the response spectrum of any single earthquake. Thus it serves as a ‘smooth design spectrum’ and can be used to approximate structural response to a future seismic event.

Low Cost Seismic Strengthening of Power System

Low cost measures are presented that could prevent damage to power systems during future seismic events. In a high seismicity region, a cost increase of few percent can reasonably be expected to provide adequate seismic resistance. In a region of low or moderate seismicity, however, the earthquake probabilities are so low that the increase of construction costs which can be justified is almost nil because the probabilities are so low. The key words regarding earthquake resistance are: anchor, brace, separate, guide, cushion, latch, limit, select and plan. The effects of earthquakes on hydroelectic power plants, thermal power plants, transmission systems, and distribution systems are reviewed.