Thursday, September 1, 2011

The Tangiwai and Ruapehu disaster

The Tangiwai and Ruapehu disaster



Poised for disaster


Mt Ruapehu erupted in 1945, but by the end of the year the excitement was over. The crater, about 300 metres deep, slowly refilled with water. The mountain did not seem dangerous, and it was no longer being monitored. By 1953, however, Crater Lake was 8 metres higher than its level before 1945. Few realised that the water was now held in by an unstable mass of ice and volcanic rubble and ash.



The lahar

At 8 p.m. on Christmas Eve 1953, the debris at the outlet of Crater Lake collapsed. About 340,000 cubic metres of water poured into the head of the Whangaehu River and swept down the valley, picking up sand, silt and boulders as it went. Soon after 10 p.m. this volcanic mud flow, known as a lahar, smashed into the main trunk railway bridge at Tangiwai. The concrete piers were knocked out and the bridge partially collapsed.



Driving through the darkness, Cyril Ellis stopped when he saw that the bridge ahead was under water, even though there had been no rain. Realising that a train was approaching the nearby rail bridge, he ran along the track towards it, waving a torch to flag it down. It was the passenger express from Wellington, packed with 285 people heading to Auckland for the holidays.



The train reaches the bridge

The driver saw him and applied the brakes, but the train’s momentum carried it out onto the bridge. The engine and first carriage nosedived, landing against the opposite bank. Four more carriages plunged into the river, floating in the torrent briefly before sinking. Another four carriages remained on the track, but one of them dangled over the river. Ellis and guard William Inglis attempted to help people off, but the coupling snapped and the carriage toppled into the river. Rolling several times, it came to rest on its side, with water flowing through it. Ellis knocked out several windows and hoisted people outside as passenger John Holman lifted fellow travellers out to him. In all, 26 people escaped, huddled on the carriage for over an hour until the torrent subsided. The men then formed a human chain in waist-deep water, helping everyone reach the bank safely.



On the other side of the flooded road bridge, Arthur Bell and his wife had also seen the train crash into the river. Mrs Bell went for help, while Arthur assisted 15 people from the carriage that had hit the riverbank.



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