Other websites with information on volcanic hazards and infrastructure include:
Auckland it's our Volcano: www.auckland.ac.nz/AIOV
Cities and Volcanoes commission of IAVCEI: http://cav.volcano.info/
International Volcanic Health Hazard Network: http://www.ivhhn.org/
USGS volcanic ash impacts page: http://volcanoes.usgs.gov/ash/
USGS natural hazards gateway: http://www.usgs.gov/hazards/
ARC hazards pages: http://www.arc.govt.nz/arc/environment/hazards/
Natural Hazards Centre: http://www.naturalhazards.net.nz/
GNS volcanoes page: http://www.gns.cri.nz/what/earthact/volcanoes/index.html
GNS hazard watch: http://www.hazardwatch.co.nz/
EQ-IQ (EQC): http://www.eq-iq.org.nz/
GeoNet: http://www.geonet.org.nz/index.html
Global Volcanism Program: http://www.volcano.si.edu/