Eastern Ruapehu Lahar Alarm and Warning System
Fresh lahar channels are visible on Ruapehu's eastern slopes, 27 March 2007. The Eastern Ruapehu Lahar Alarm and Warning System , or ERLAWS , is a lahar warning system that was installed on Mount Ruapehu, New Zealand following volcanic eruptions in 1995–1996. The system successfully detected and warned of an imminent lahar in March 2007. The system is being expanded to detect the wider range of lahar threats now expected on Ruapehu. Contents 1 Introduction 2 Sensors 3 Monitoring 4 Transit systems 5 Events 6 Expansion 7 References Introduction The 1995–1996 eruptions of Ruapehu in the North Island of New Zealand left a 7-metre high dam of tephra, consisting of volcanic ash and rock, around the rim of the crater lake. It was realised that some time after the lake refilled and rose above the level of its normal outlet, the tephra dam would collapse, causing a large lahar. Such a lahar resulted in the 1953 Tangiwai disaster when 151...