Design and Manufacture of Portable Strong Motion Instrument for Array Observation and Observation/Analysis Manual

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This study focused on manufacturing portable strong motion observation instruments and developing array observation methods, certifying a easy mobile observation just after a large earthquake occurrence and/or in case of emergency. In the first year of this project, we compared the features of exiting instruments, surveyed the possible new specifications of instruments and manufactured a sensor and a data logger as a trial. Next year, we examined the trials obtaining the results from several tests and determined finally the specifications for new instruments. A moving-coil type accelerometer was selected as a sensor, because it require no power supply. The principal specifications of the sensor are that it is observable from microtremors level until very strong one like the Kobe cases (150cm/s) and it has a flat response from 0.07Hz to 100Hz. The data logger used 24 bits A/D converter achieved a dynamic ange of 130 dB and it needs less power supply. The total weight of the new instrument without battery is 3 kg. In the third year, we examined the new instruments in the field for array observation of earthquake as well as microtremors, not only in Japan but also in U.S.A.and Greece. It was confirmed through the various field tests that the new instruments were very useful for mobile array observations.