TY - JOUR TI - Standardisation of the USGS Volcano Alert Level System (VALS): analysis and ramifications U1 - Further reading JF - Bulletin of Volcanology AU - Fearnley, C. J. AU - McGuire, W. J. AU - Davies, G. AU - Twigg, J. DO - 10.1007/s00445-012-0645-6 PY - 2012-11 EP - 2036 SP - 2023 SN - 0258-8900 SN - 1432-0819 IS - 9 VL - 74 ER -