WELLINGTON, New Zealand (AP) — A New Zealand volcano has erupted for the second time in less than four months, sending a dark ash plume about 3 kilometers (1.9 miles) into the sky.

Authorities issued a no-fly alert above Mount Tongariro on central North Island after it erupted Wednesday afternoon. Scientists say the eruption did not cause any damage or force road closures and that planes could divert around the mountain.

Volcanologist Tony Hurst says the eruption was unexpected, although scientists had placed the volcano on a higher alert after it erupted in August for the first time in more than a century.

Hurst said the dark ash indicated magma pressure deep underground caused the eruption. A steam-driven eruption typically produces white ash.

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