Note: This VAL system was in use from 1991–June 1997. The current VAL system can be found here.
Agency: United States Geological Survey (USGS)
Name: Status Ranking and Activity Levels
Elements of VAL system
| Domain | Terrestrial |
| Volcano | California |
| Scheme range | 6-level scale |
| Lowest level | 1 |
| Highest level | 6 |
| Level name type | Word |
| Level for lack/loss of monitoring | No |
| Volcanic activity | Yes |
| Hazards possible | No |
| Locations affected | No |
| Potential impacts | No |
| Forecast language | Yes |
| Timing language | Yes |
| Actions to take | No |
| Agency actions | Yes |
| Link to evacuations | No |
| Reporting frequency per level | No |
| Link to monitoring thresholds | Yes |
| Step-up and step-down language | No |
Related References
Fearnley, C. J., McGuire, W. J., Davies, G., & Twigg, J. (2012). Standardisation of the USGS Volcano Alert Level System (VALS): analysis and ramifications. Bulletin of Volcanology, 74(9), 2023-2036. https://doi.org/10.1007/s00445-012-0645-6
Hill, D. P., Johnston, M. J., Langbein, J. O., McNutt, S. R., Miller, C. D., Mortensen, C. E., & Pitt, A. M. (1991). Response plans for volcanic hazards in the Long Valley caldera and Mono Craters area, California Open-File Report No. 91-270. US Dept. of the Interior, US Geological Survey. https://doi.org/10.3133/ofr91270
Hill, D. P., Mangan, M. T., & McNutt, S. R. (2017). Volcanic unrest and hazard communication in Long Valley volcanic region, California.In: Fearnley, C.J., Bird, D.K., Haynes, K., McGuire, W.J., Jolly, G. (eds) Observing the Volcano World. Advances in Volcanology. Springer, Cham. (pp. 171-187). https://doi.org/10.1007/11157_2016_32