Volcanoes - Ministry of Civil Defence and Emergency Management

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• Lifeline utility preparedness: Auckland lifeline utility operators are undertaking coordinated volcanic impacts research, and response and recovery planning. AUCKLAND VOLCANO-SEISMIC MONITORING NETWORK The Auckland Volcano-Seismic Monitoring Network (AVSN) comprises five sites geographically distributed around the Auckland Volcanic Field (AVF), at which seismic activity is continuously monitored (Fig 1). The data is collected and radioed to a central recording site at the Auckland Regional Council, where it is digitally recorded and then transmitted to the Institute of Geological and Nuclear Sciences at Wairakei and Wellington. The incoming data is monitored in near real time 24 hours a day, 7 days a week by specialised computer software. Should any change in the prevailing seismic pattern be detected, a 24 hour duty officer is automatically paged who can provide warning of an impending volcanic eruption within a short time of the initial precursory seismicity (potentially within 1 hour). Should volcanic activity be detected, additional seismometers would be deployed adjacent to the suspected vent location. To identify locations that have low day to day environmental ground movements that Fig 1: Auckland Volcano-Seismic Monitoring Network. could potentially mask volcanic seismicity, a portable seismometer is annually deployed for a day or two at a variety of sites throughout the AVF. VOLCANIC CONTINGENCY PLAN The Contingency Plan for the Auckland Volcanic Field helps to establish coordinated response and restoration operations by: 1. Establishing protocols for the timely and efficient warning of volcanic activity. Hazard Areal extent Anticipated Loss Recovery period following cessation of activity Earthquake Crater, Cone or Ring Formation Ground shaking, uplift and deformation affect an area of up to 3 to 5km 2 . Crater of up to 1.5km diameter produced with anticipated maar stretching a 300-500m radius. Formation of steep sided scoria cones of up to 1 km across. Small Extreme Not applicable Several months to years Fire Fountaining Significant effects 200-500m from vent. Extreme 1 week to several months Lava AVF lavas have travelled 0.5-9.5km from vent. High Several weeks to several months Base Surge Surges flow out to 5km from vent. Near vent deposits likely to be greater than 0.2m thick. Extreme 1 week to several months Shock Waves Affect areas 3-5km from vent. High 1 week to several months Lava bombs Airfall Tephra Gas Lightning Tsunami Table 1: Most bombs deposited within 0.4km of vent, but may extend to 1 to 2km. Ash plume may rise 6-15km resulting in deposition of tephra up to 100km from vent. Asphyxiating gases CO, CO 2 , and HF are likely to be localised around vent (up to 3-5km), and concentrated in low-lying areas. Acid rain up to 10km from vent. Immediate area of eruption column and plume and up to 10km downwind of the vent. Affect low lying coastal areas within 1km of the disturbance. Anticipated hazards associated with Auckland Volcanic Field eruptions. Moderate Low Moderate Low Low 1 week to several months 1 week to several months Not applicable Up to 1-2 days Up to 1-2 days 34 TEPHRA June 2004
2. Allowing for immediate communication and public information activities. 3. Specifying roles and responsibilities of responding organisations. 4. Ensuring that declarations are made as necessary and that the process of declaration is transparent for those involved in civil defence emergency management 5. Providing guidance on appropriate dissemination of information for the management of the civil defence emergency 6. Appropriate prioritisation and allocation of regional resources. In the Auckland context, managing the provision of warning is made more difficult as the eruption will occur in an as yet new unknown location, and warning periods are likely to be short. Consequently, a unique system to help manage these circumstances has been developed as part of the Contingency Plan for the Auckland Volcanic Field (VCP). This system utilises: • Scientific Alert Levels (Scott, 2001) defining the status of a reawakening volcano at any time (Table 2) • Warning Phases (Figure 2) • Hazard Zone Overlay (Figure 3) VOLCANIC WARNINGS IN THE AUCKLAND VOLCANIC FIELD Precursory seismicity will be detected by the Auckland Volcano-Seismic Monitoring Network. As volcanic type activity escalates, Scientific Alert Levels and Warning Phases are issued. Auckland Volcanic Field - Relative age and volcano distribution. Scientific Alert Level Indicative Phenomena Volcano Status Warning Phase *Period 0 Typical background surface activity; deformation, seismicity, and heath flow at low levels. Usual dormant or quiescent state. Advisory Phase Not applicable. 1 Apparent seismic, geodetic, thermal or other unrest indicators. 2 Increase in number or intensity of unrest indicators (seismicity, deformation, heat flow etc). 3 Minor steam eruptions. High increasing trends of unrest indicators, significant effects on volcano, possible beyond. 4 Eruption of new magma. Sustained high levels of unrest indicators, significant effects beyond volcano. 5 Destruction with major damage beyond active volcano. Significant risk over wider areas. Initial signs of possible volcano unrest. No eruption threat. Confirmation of volcano unrest. Eruption threat. Minor eruptions commenced. Real possibility of hazardous eruptions. Hazardous local eruption in progress. Large-scale eruption now possible. Large hazardous volcanic eruption in progress. Alert/Warning Phase I or II A few days and up to a few weeks. Warning Phase II Up to 1 to 3 days Warning Phase III Warning Phase IV Warning Phase IV A few hours to 1 day Up to a few hours Not applicable *Warning periods assessed for the Auckland Volcanic Field. Periods have been assigned to Scientific Alert Levels (SALs) as a tool for planning purposes only. The SAL may rise to 1 and then return to 0 and is not intended to be a predictive tool. NOTE: The periods indicated in the table do not reflect either the minimum or maximum duration of each level, but provide an indication of a realistic lower bound time period between warning levels. These periods are an indication of the mobilisation or resourcing time that can be anticipated. Table 2: Scientific Alert Levels and Warning Phases used for the Contingency Plan for the Auckland Volcanic Field. 35 TEPHRA June 2004
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Volcanoes - Ministry of Civil Defence and Emergency Management

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