Bulletin of Volcanology

, 77:77 | Cite as

Introducing the Volcanic Unrest Index (VUI): a tool to quantify and communicate the intensity of volcanic unrest

  • Sally H. Potter
  • Bradley J Scott
  • Gill E Jolly
  • Vince E Neall
  • David M Johnston
Research Article


Accurately observing and interpreting volcanic unrest phenomena contributes towards better forecasting of volcanic eruptions, thus potentially saving lives. Volcanic unrest is recorded by volcano observatories and may include seismic, geodetic, degassing and/or geothermal phenomena. The multivariate datasets are often complex and can contain a large amount of data in a variety of formats. Low levels of unrest are frequently recorded, causing the distinction between background activity and unrest to be blurred, despite the widespread usage of these terms in unrest literature (including probabilistic eruption-forecasting models) and in Volcanic Alert Level (VAL) systems. Frequencies and intensities of unrest episodes are not easily comparable over time or between volcanoes. Complex unrest information is difficult to communicate simply to civil defence personnel and other non-scientists. The Volcanic Unrest Index (VUI) is presented here to address these issues. The purpose of the VUI is to provide a semi-quantitative rating of unrest intensity relative to each volcano’s past level of unrest and to that of analogous volcanoes. The VUI is calculated using a worksheet of observed phenomena. Ranges for each phenomenon within the worksheet can be customised for individual volcanoes, as demonstrated in the companion paper for Taupo Volcanic Centre, New Zealand (Potter et al. 2015). The VUI can be determined retrospectively for historical episodes of unrest based on qualitative observations, as well as for recent episodes with state-of-the-art monitoring. This enables a long time series of unrest occurrence and intensity to be constructed and easily communicated to end users. The VUI can also assist with VAL decision-making. We present and discuss two approaches to the concept of unrest.


VUI Volcanic unrest Communication Caldera unrest Volcano monitoring Earthquakes Deformation Hydrothermal 



The authors would like to thank contributing scientists, including from GNS Science, US Geological Survey, and various universities; Jan Lindsay for the encouragement, S.H. Potter’s PhD examiners for the feedback and New Zealand stakeholders for their input to the VUI. Thank you to Chris Newhall, an anonymous reviewer, and Servando De la Cruz-Reyna and James White for valuable comments. This project was supported by public research funding from the Government of New Zealand through GNS Science and the New Zealand Earthquake Commission. Thank you to the Claude McCarthy Fellowship for assisting with travel costs and to Massey University for supplying resources.


  1. Agresti A (2010) Analysis of ordinal categorical data. Wiley, New JerseyCrossRefGoogle Scholar
  2. Albano SE, Matsumoto N, Newhall CG, Koizumi N, Sato T (2002) Mechanisms of groundwater level changes at volcanoes. Eos, Trans Am Geophys Union 83(47):1–F1485Google Scholar
  3. Asch SE (1952) Social psychology. Englewood Cliffs, Prentice-HallCrossRefGoogle Scholar
  4. Barberi F, Corrado G, Innocenti F, Luongo G (1984) Phlegraean Fields 1982–1984: brief chronicle of a volcano emergency in a densely populated area. Bull Volcanol 47(2):175–185CrossRefGoogle Scholar
  5. Barberi F, Bertagnini A, Landi P, Principe C (1992) A review on phreatic eruptions and their precursors. J Volcanol Geotherm Res 52(4):231–246CrossRefGoogle Scholar
  6. Bell AF, Naylor M, Heap MJ, Main IG (2011) Forecasting volcanic eruptions and other material failure phenomena: an evaluation of the failure forecast method. Geophys Res Lett 38, L15304Google Scholar
  7. Benoit JP, McNutt SR (1996) Global volcanic earthquake swarm database 1979-1989. U.S. Geological Survey, WashingtonGoogle Scholar
  8. Blong RJ (2003) A review of damage intensity scales. Nat Hazards 29(1):57–76CrossRefGoogle Scholar
  9. Bonneville A, Gouze P (1992) Thermal survey of mount Etna volcano from space. Geophys Res Lett 19(7):725–728CrossRefGoogle Scholar
  10. Browne PRL, Lawless JV (2001) Characteristics of hydrothermal eruptions, with examples from New Zealand and elsewhere. Earth Sci Rev 52(4):299–331CrossRefGoogle Scholar
  11. Chouet BA (1996) Long-period volcano seismicity: its source and use in eruption forecasting. Nature 380(6572):309–316CrossRefGoogle Scholar
  12. Daag AS, Tubianosa BS, Newhall CG, Tungol NM, Javier D, Dolan MT, Delos Reyes PJ, Arboleda RA, Martinez ML, Regalado TM (1996) Monitoring sulfur dioxide emission at Mount Pinatubo. In: Newhall CG, Punongbayan RS (eds) Fire and Mud: eruptions and lahars of mount Pinatubo Philippines. Philippine Institute of Volcanology and Seismology, Quezon City, pp 409–414Google Scholar
  13. Davy BW, Caldwell TG (1998) Gravity, magnetic and seismic surveys of the caldera complex, lake taupo, north island, New Zealand. N Z J Volcanol Geotherm Res 81:69–89CrossRefGoogle Scholar
  14. Decker RW (1986) Forecasting volcanic eruptions. Annual Rev Earth Planet Sci 14(1):267–291CrossRefGoogle Scholar
  15. Delmelle P, Stix J (2000) Volcanic gases. In: Sigurdsson H, Houghton BF, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of volcanoes. Academic Press, San Diego, pp 803–815Google Scholar
  16. Endo ET, Murray T (1991) Real-time seismic amplitude measurement (RSAM): a volcano monitoring and prediction tool. Bull Volcanol 53(7):533–545CrossRefGoogle Scholar
  17. Endo ET, Murray TL, Power JA (1996) A comparison of preeruption real-time seismic amplitude measurements for eruptions at Mount St. Helens, Redoubt Volcano, Mount Spurr, and Mount Pinatubo. In: Newhall C, Punongbayan RS (eds) Fire and mud: eruptions and lahars of Mount Pinatubo Philippines. University of Washington Press, Quezon City, pp 233–247Google Scholar
  18. Fearnley CJ (2013) Assigning a volcano alert level: negotiating uncertainty, risk, and complexity in decision-making processes. Environ Plan A 45(8):1891–1911CrossRefGoogle Scholar
  19. Fearnley CJ, McGuire WJ, Davies G, Twigg J (2012) Standardisation of the USGS Volcano Alert Level System (VALS): analysis and ramifications. Bull Volcanol 74(9):2023–2036CrossRefGoogle Scholar
  20. Folch A, Gottsmann J (2006) Faults and ground uplift at active calderas. Geol Soc Lond Spec Publ 269(1):109–120CrossRefGoogle Scholar
  21. Garcia-Aristizabal A, Selva J, Fujita E (2013) Integration of stochastic models for long-term eruption forecasting into a Bayesian event tree scheme: a basis method to estimate the probability of volcanic unrest. Bull Volcanol 75(2):1–13CrossRefGoogle Scholar
  22. Gardner CA, Guffanti MC (2006) U.S. Geological Survey's alert notification system for volcanic activityGoogle Scholar
  23. Guffanti MC, Miller TP (2013) A volcanic activity alert-level system for aviation: review of its development and application in Alaska. Nat Hazards 69:1519–1533CrossRefGoogle Scholar
  24. Guidoboni E, Ciuccarelli C (2011) The Campi Flegrei caldera: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 AD). Bull Volcanol 73(6):655–677CrossRefGoogle Scholar
  25. Harlow DH, Power JA, Laguerta EP, Ambubuyog G, White RA, Hoblitt RP (1996) Precursory seismicity and forecasting of the June 15, 1991, eruption of Mount Pinatubo. In: Newhall CG, Punongbayan RS (eds) Fire and mud: eruptions and lahars of Mount Pinatubo Philippines. Philippine Institute of Volcanology and Seismology, Quezon City, pp 285–305Google Scholar
  26. Hill DP (1998) SSA meeting presidential address: science, geologic hazards, and public in a large, restless caldera. Seismol Res Lett 69(5):400–404CrossRefGoogle Scholar
  27. Hochstein MP, Browne PRL (2000) Surface manifestations of geothermal systems with volcanic heat sources. In: Encyclopedia of Volcanoes. Academic Press, pp 835-855Google Scholar
  28. Hurst AW, McGinty PJ (1999) Earthquake swarms to the west of Mt Ruapehu preceding its 1995 eruption. J Volcanol Geotherm Res 90(1–2):19–28CrossRefGoogle Scholar
  29. Hurwitz S, Johnston MJS (2003) Groundwater level changes in a deep well in response to a magma intrusion event on Kilauea Volcano. Hawai'i Geophys Res Lett 30(22):2173CrossRefGoogle Scholar
  30. Inhaber H (1976) Environmental indices. Wiley, OttawaGoogle Scholar
  31. Janis IL (1982) Groupthink: psychological studies of policy decisions and fiascoes. Houghton Mifflin Company, Boston, p 349Google Scholar
  32. Jaupart C (2000) Magma ascent at shallow levels. In: Houghton BF, McNutt SR, Rymer H, Stix J, Sigurdsson H (eds) Encyclopedia of Volcanoes. Academic Press, San Diego, pp 237–245Google Scholar
  33. Johnston DM, Scott BJ, Houghton B, Paton D, Dowrick DJ, Villamor P, Savage J (2002) Social and economic consequences of historic caldera unrest at the Taupo volcano, New Zealand and the management of future episodes of unrest. Bull N Z Soc Earthq Eng 35(4):215–230Google Scholar
  34. Kilburn CRJ (2003) Multiscale fracturing as a key to forecasting volcanic eruptions. J Volcanol Geotherm Res 125(3-4):271–289CrossRefGoogle Scholar
  35. Kilburn CRJ, Sammonds PR (2005) Maximum warning times for imminent volcanic eruptions. Geophys Res Lett 32(24), L24313CrossRefGoogle Scholar
  36. Kilgour G, Manville V, Della Pasqua F, Graettinger A, Hodgson KA, Jolly GE (2010) The 25 September 2007 eruption of Mount Ruapehu, New Zealand: Directed ballistics, surtseyan jets, and ice-slurry lahars. J Volcanol Geotherm Res 191(1–2):1–14CrossRefGoogle Scholar
  37. Langbein JO (2003) Deformation of the Long Valley Caldera, California: inferences from measurements from 1988 to 2001. J Volcanol Geotherm Res 127(3-4):247–267CrossRefGoogle Scholar
  38. Lehmann DR, Gupta S, Steckel JH (1998) Marketing research. Addison-Wesley Educational Publishers Inc., p 780Google Scholar
  39. Lowenstein PL (1988) The Rabaul seismo-deformational crisis of 1983-85; monitoring, emergency planning and interaction with the authorities, the media and the public. In: Kagoshima international conference on volcanoes, 1988. Natl. Inst. Res. Advanc, KagoshimaGoogle Scholar
  40. Lowry AR, Hamburger MW, Meertens CM, Ramos EG (2001) GPS monitoring of crustal deformation at Taal Volcano Philippines. J Volcanol Geotherm Res 105(1-2):35–47CrossRefGoogle Scholar
  41. Mader GG, Blair ML (1987) Living with a volcanic threat: response to volcanic hazards, Long Valley, California. William Spangle and Associates, Portola Valley, California, p 105Google Scholar
  42. Malone SD, Boyko C, Weaver CS (1983) Seismic precursors to the Mount St. Helens eruptions in 1981 and 1982. Am Assoc Adc Sci 221(4618):1376–1378Google Scholar
  43. Martí J, Ortiz R, Gottsmann J, Garcia A, De La Cruz-Reyna S (2009) Characterising unrest during the reawakening of the central volcanic complex on Tenerife, Canary Islands, 2004-2005, and implications for assessing hazards and risk mitigation. J Volcanol Geotherm Res 182(1-2):23–33CrossRefGoogle Scholar
  44. Martini M (1996) Chemical characters of the gaseous phase in different stages of volcanism: precursors and volcanic activity. In: Scarpa R, Tilling RI (eds) Monitoring and mitigation of volcanic hazard. Springer, Berlin Heidelberg, pp 200–219Google Scholar
  45. Marzocchi W (2002) Remote seismic influence on large explosive eruptions. J Geophys Res 107(B1):7Google Scholar
  46. Marzocchi W, Sandri L, Gasparini P, Newhall C, Boschi E (2004) Quantifying probabilities of volcanic events: the example of volcanic hazard at Mount Vesuvius. J Geophys Res 109(B11201)Google Scholar
  47. Marzocchi W, Sandri L, Selva J (2008) BET_EF: a probabilistic tool for long- and short-term eruption forecasting. Bull Volcanol 70(5):623–632CrossRefGoogle Scholar
  48. MCDEM (2006) The guide to the national civil defence emergency management plan 2006. Ministry of Civil Defence & Emergency Management, Wellington, p 266Google Scholar
  49. McNutt SR (1992) Volcanic tremor. In: Encyclopedia of Earth System Science. Academic Press, Inc., pp 417-425Google Scholar
  50. McNutt SR (1996) Seismic monitoring and eruption forecasting of volcanoes: a review of the state-of-the-art and case histories. In: Scarpa R, Tilling RI (eds) Monitoring and mitigation of volcano hazards. pp 99-146Google Scholar
  51. McNutt SR (2000) Volcanic seismicity. In: Sigurdsson H, Houghton BF, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of volcanoes. Academic Press, San Diego, pp 1015–1033Google Scholar
  52. McNutt SR (2005) Volcanic seismology. Annu Rev Earth Planet Sci 32:461–491CrossRefGoogle Scholar
  53. McNutt SR, Nishimura T (2008) Volcanic tremor during eruptions: temporal characteristics, scaling and constraints on conduit size and processes. J Volcanol Geotherm Res 178(1):10–18CrossRefGoogle Scholar
  54. Mogi K (1958) Relations between eruptions of various volcanoes and the deformations of the ground surfaces around them. Bull Earthq Res Inst 36:99–134Google Scholar
  55. Moran SC, Newhall CG, Roman DC (2011) Failed magmatic eruptions: late-stage cessation of magma ascent. Bull Volcanol 73(2):115–122CrossRefGoogle Scholar
  56. Mueller SB, Varley NR, Kueppers U, Lesage P, Reyes Davila GÁ, Dingwell DB (2013) Quantification of magma ascent rate through rockfall monitoring at the growing/collapsing lava dome of Volcán de Colima, Mexico. Solid Earth 4:201–203CrossRefGoogle Scholar
  57. Murray JB, Rymer H, Locke CA (2000) Ground deformation, gravity, and magnetics. In: Sigurdsson H, Houghton BF, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of volcanoes. Academic Press, San Diego, pp 1121–1140Google Scholar
  58. Newhall CG, Dzurisin D (1988) Historical unrest at large calderas of the world. U. S. Geological Survey Bulletin 1855, Washington, D.C.Google Scholar
  59. Newhall CG, Hoblitt R (2002) Constructing event trees for volcanic crises. Bull Volcanol 64(1):3–20CrossRefGoogle Scholar
  60. Newhall CG, Self S (1982) The volcanic explosivity index (VEI): an estimate of explosive magnitude for historical volcanism. J Geophys Res 87(C2):1231–1238CrossRefGoogle Scholar
  61. Newhall CG, Albano SE, Matsumoto N, Sandoval T (2001) Roles of groundwater in volcanic unrest. J Geol Soc Philippines 56:69–84Google Scholar
  62. Newman AV, Stiros S, Feng L, Psimoulis P, Moschas F, Saltogianni V, Jiang Y, Papazachos C, Panagiotopoulos D, Karagianni E, Vamvakaris D (2012) Recent geodetic unrest at Santorini Caldera. Greece Geophys Res Lett 39(6):5Google Scholar
  63. Otway PM, Blick GH, Scott BJ (2002) Vertical deformation at Lake Taupo, New Zealand, from lake levelling surveys, 1979-99. N Z J Geol Geophys 45(1):121–132CrossRefGoogle Scholar
  64. Phillipson G, Sobradelo R, Gottsmann J (2013) Global volcanic unrest in the 21st century: an analysis of the first decade. J Volcanol Geotherm Res 264:183–196CrossRefGoogle Scholar
  65. Potter SH (2014) Communicating the status of volcanic activity in New Zealand, with specific application to caldera unrest. Ph.D. thesis submitted in February 2014 to Massey University, Wellington, New ZealandGoogle Scholar
  66. Potter, SH, Jolly, GE, Neall, VE, Johnston, DM, Scott, BJ (2014) Communicating the status of volcanic activity: revising New Zealand's volcanic alert level system. J. Applied Volcanol. 3(1):13Google Scholar
  67. Potter SH, Scott BJ, Jolly GE, Johnston DM, Neall VE (2015) A catalogue of caldera unrest at Taupo Volcanic Centre, New Zealand, using the Volcanic Unrest Index (VUI). Bull Volcanol doi: 10.1007/s00445-015-0956-5
  68. Price M (1985) Introducing groundwater. Chapman & Hall, London, p 195Google Scholar
  69. Ronan KR, Paton D, Johnston DM, Houghton BF (2000) Managing societal uncertainty in volcanic hazards: a multidisciplinary approach. Disaster Prev. Manag 9(5):339–349Google Scholar
  70. Rothery DA, Oppenheimer C, Bonneville A (1995) Infrared thermal monitoring. In: McGuire B, Kilburn CRJ, Murray J (eds) Monitoring active volcanoes. UCL Press, London, pp 184–216Google Scholar
  71. Rymer H (1994) Microgravity change as a precursor to volcanic activity. J Volcanol Geotherm Res 61(3-4):311–328CrossRefGoogle Scholar
  72. Sandri L, Marzocchi W, Zaccarelli L (2004) A new perspective in identifying the precursory patterns of eruptions. Bull Volcanol 66(3):263–275CrossRefGoogle Scholar
  73. Scott BJ (2013) A revised catalogue of Ruapehu volcano eruptive activity: 1830-2012. GNS Science Report 2013/45, p 107Google Scholar
  74. Scott BJ, Travers J (2009) Volcano monitoring in NZ and links to SW Pacific via the Wellington VAAC. Nat Hazards 51(2):263–273CrossRefGoogle Scholar
  75. Sherburn S, Bryan CJ, Hurst AW, Latter JH, Scott BJ (1999) Seismicity of Ruapehu volcano, New Zealand, 1971-1996: a review. J Volcanol Geotherm Res 88(4):255–278CrossRefGoogle Scholar
  76. Shibata T, Akita F, Hirose W, Ikeda R (2008) Hydrological and geochemical change related to volcanic activity of Usu volcano. Japan J Volcanol Geotherm Res 173(1–2):113–121CrossRefGoogle Scholar
  77. Sparks RSJ (2003) Forecasting volcanic eruptions. Earth Planet Sci Lett 210(1-2):1–15CrossRefGoogle Scholar
  78. Stoner JAF (1961) A comparison of individual and group decisions involving risk. Unpublished M.Sc. thesis, Massachusetts Institute of TechnologyGoogle Scholar
  79. Swanson DA, Casadevall TJ, Dzurisin D, Malone SD, Newhall CG, Weaver CS (1983) Predicting eruptions at Mount St. Helens, June 1980 through December 1982. Sci 221(4618)Google Scholar
  80. Swanson DA, Casadevall TJ, Dzurisin D, Holcomb RT, Newhall CG, Malone SD, Weaver CS (1985) Forecasts and predictions of eruptive activity at Mount St. Helens, USA: 1975–1984. J Geodyn 3(3-4):397–423CrossRefGoogle Scholar
  81. Toutain JP, Bachelery P, Blum PA, Delorme H, Kowalski P (1995) Real-time ground deformation monitoring. In: McGuire B, Kilburn CRJ, Murray J (eds) Monitoring active volcanoes: strategies, procedures, and techniques. UCL Press, London, pp 93–109Google Scholar
  82. Umakoshi K, Shimizu H, Matsuwo N (2001) Volcano-tectonic seismicity at Unzen Volcano, Japan, 1985–1999. J Volcanol Geotherm Res 112(1–4):117–131CrossRefGoogle Scholar
  83. Van der Laat R (1996) Ground-deformation methods and results. In: Scarpa R, Tilling RI (eds) Monitoring and mitigation of volcano hazards. Springer, Berlin, pp 147–168CrossRefGoogle Scholar
  84. Voight B (1988) A method for prediction of volcanic eruptions. Nature 332:125–130CrossRefGoogle Scholar
  85. Voight B (1989) A relation to describe rate-dependent material failure. Am Assoc Adv Sci 243(4888):200–203Google Scholar
  86. Voight B, Cornelius RR (1991) Prospects for eruption prediction in near real-time. Pros Erup Pred Near real-time 350(6320):695–698Google Scholar
  87. Zobin VM (2003) Introduction to volcanic seismology. Elsevier, pp xi, 290Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Sally H. Potter
    • 1
  • Bradley J Scott
    • 2
  • Gill E Jolly
    • 1
  • Vince E Neall
    • 3
  • David M Johnston
    • 1
  1. 1.GNS ScienceLower HuttNew Zealand
  2. 2.GNS ScienceTaupoNew Zealand
  3. 3.Massey UniversityPalmerston NorthNew Zealand

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