Debris Flow Detection Using LVP Sensors in Japan

Hitoshi KATO, Nobuyuki NODA, Kazuhiko HASHI, Satoshi TAGATA, Takahiro ITOH and Takahisa MIZUYAMA

Sakura-jima Island is an active volcano in the southwest region of Kyushu in Japan. The area surrounding the volcano is impacted by significant debris flows when rainfall follows an eruption. Various studies have investigated the use of sensors including wire sensors and accelerometers to detect such events. Wire sensors typically incorporate three horizontal wires set at heights of 60, 120, and 180 cm from the river bed and can be used to quantify the magnitude of the debris flow. We have developed an LVP (load, vibration, pressure) sensor [Itoh et al., 2017] and installed it at two test sites to establish its suitability for continuous detection of debris flows. The sensor consists of a load cell, an accelerometer, and a pressure meter. The sensor is mainly used for debris flow detection but also measures the load of the surge. In this paper, we present the results of an analysis of LVP and wire sensor data that were recorded at the test sites to verify the accuracy of the LVP data, and propose threshold values for debris flow occurrences which were observed using the LVP sensors.

2018/1 355-362