Abstract
In relation to the Great East Japan Earthquake (the 2011 off the Pacific coast of Tohoku Earthquake), a number of abnormal phenomena, including rumbling of the ground, groundwater eruption and ground subsidence, occurred in areas of abandoned coal mines in Iwaki City, Fukushima Prefecture, in March 2011. The Society of Exploration Geophysicists of Japan (SEGJ) was consulted by the Iwaki City Office about professional knowledge and advices on these geological hazards. After the discussion in the Board of Directors, SEGJ decided to carry out emergency geophysical surveys in Iwaki City. The target area of the surveys was first limited in the disaster areas in abandoned coal mines. However, at the beginning of the field work, a large earthquake (after shock), with a magnitude of 7.0, hit Iwaki City on April 11, 2011. The survey targets were expanded to include the active faults and the stricken areas by the after shock.
In this paper, assuming that our society will conduct emergency geophysical surveys at an occurrence of large-scale natural disasters in the future, we reviewed the activities and results of the emergency surveys conducted in Iwaki City, including how SEGJ decided the execution of the emergency surveys and how the survey contents were modified as the situation of the survey areas changed. In addition, in order to examine the effectiveness of the emergency surveys with respect to the needs of the City Office and the local people who live in the disaster areas, we conducted a self evaluation on successful results and unsolved problems of the surveys, by applying the five items of business evaluation defined by the Development Assistance Committee of the Organization for Economic Co-operation and Development (OECD). We also pointed out that it is essential to conduct such evaluation at each of the emergency surveys that our society will conduct in the future.
