長時間地震観測磁気テープ記録のディジタル処理
TOSBAC-3400, TOSBAC-40 SYSTEM とそのA/D, D/A変換器の利用
1975 年 28 巻 4 号 p. 379-386
詳細
1975 年 28 巻 4 号 p. 379-386
Methods of earthquake detection from a long time analog tape recording have been developed. In these methods, the detection of earthquakes is done by an interpreter looking at the display on the memory-scope of storage type, then the selected seismogram is picked up and stored on digital magnetic tapes by the instruction through an on-line console typewriter. The hardware system for the methods consists of an additional memory-scope of low price and an ordinary computer system including A/D and D/A converters. By the present technique, 7-days data which includes 30 earthquakes is processed within several hours.
We have developed two methods. In the first step of the first method, all analog records are once digitized and stored on digital magnetic tapes with a high speed of 50 times that of recording. Then in the second step, the converted digital data are displayed on the memory-scope with a high speed of 80 times that of recording. Data of the recognized earthquakes are eddited and stored on a new digital magnetic tape by the interpreter's instruction.
In the second method, analog data are digitized with a speed of 50 times that of recording and displayed on the memory-scope simultaneously. Selected data are eddited and stored on a new digital magnetic tape when needed.
In the first method, it takes 4 hours for the first step and 2.5 hours for the second step in processing the data of one week which contains about 30 earthquakes, while in the second method it takes 4.5 hours for the same data. In the first method, a monitor's working time is shorter and its first step can be carried out by the use of a mini-computer semi-automatically, although the total time is longer than in the second method.
The importance of eye inspection of the visible record shall remain in the future, even if an effective automatic earthquake detection method is developed.
