|4 - 5||Designing and manufacturing of penetrator-type seismographs|
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Because of very frequent
occurrence of pyroclastic
flows of which deposits
covered almost the whole part
of the slope of the volcano,
setting up of
observation sites was limitted
within very narrow areas during the
This made us difficult
to keep high-level observations
of the volcano.
Therefore we designed and developed penetrator-type seismographs in cooperation with the Institute of Space and Astronautical Science (ISAS) to execute high-level observations in dangerous zones close to the active crater and lower reaches of pyroclastic flow deposits. This seismograph can penetrate deep into the ground when it is droped from a helicopter.
This seismograph should withstand the impact schock sevral thousnads times the graviational acceleration, when it penetrates into the ground. Accordingly it should show the high achievement of shockproof performance.
We repeated tests of dropping from the air to improve it for the practical use at Unzen Volcano.
|Conceptual illustration of seismic observation by use of a penetrator-type seismograph.|
The trial piece used
for testing at Unzen Volcano.
The body of penetrator is made of aluminium alloy. The penetrator-type seismograph consists of a seismograph, a thermometer, a battery, a set of signal amplifier and transmitter.
The helicopter from
the Nagasaki Prefecture
Disaster Prevention Office is
the test site of the Mt.
Fugen with a trial penetrator
||The trial penetrator dropped from the helicopter well penetrated into pyroclastic deposits.|
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