Mount Tongariro, situated in a remote part of the country's North Island, erupted for five minutes on November 21, spewing clouds of ash 2.5 miles (4 kilometers) high. In August, the 6,490-foot (1,978-meter) Tongariro had erupted for the first time since 1897. (Video: Volcano 101.)
Though the recent activity seems to have ebbed, scientists have predicted another eruption of similar size will occur in the next few weeks, according to the New Zealand Herald.
Several flights were canceled on New Zealand's North Island. Previous eruptions—notably of Iceland's Eyjafjallajökull volcano in 2010—have crippled air travel on a global scale.
"Very often volcanic ash contains microscopic fragments of volcanic glass ... and the turbine engines of commercial aircraft produce a level of heat sufficient to melt glass," Steven Miller, of the Cooperative Institute for Research in the Atmosphere at Colorado State University, told NASA's Earth Observatory in August.
"The ash can melt onto [airplane] turbine blades and other parts of the engine, causing damage and even engine stalls. It also presents hazards to pilot visibility, causing pits and frosting on the windshields in the same way that a sandstorm damages an automobile windshield."