Without Warning

Every disaster leaves a mark you can point to. A crater. A scar. A field of wreckage.When help finally reached the villages around Lake Nyos in August 1986, rescuers foundalmost nothing disturbed.The houses were standing. The doors were shut. The oil lamps still held their oil.And inside those houses, out in the fields, along the paths, more than a thousand peoplelay dead beside their cattle. No wounds. No sign that anyone had tried to run.What killed them came out of the lake.Nyos sits in the highlands of northwest Cameroon, a young volcanic crater lake about 200meters deep. Magma far below the crater floor exhales carbon dioxide, constantly, andthat gas dissolves into the deep water and stays there. Nyos never turns over the way anordinary lake does. So the bottom had been loading for decades, held down by the weight ofthe water above it.Think of an unopened bottle of champagne. No bubbles. All that gas, invisible, waiting onone change in pressure.On the night of August 21, something nudged it.Roughly a cubic kilometer of carbon dioxide tore free at once. It fountained a hundredmeters above the crater rim. Then it fell back down, because CO2 is heavier than air, andpoured over the northern lip into the valleys below.The cloud was about fifty meters thick. It hugged the ground and moved downhill fasterthan a person could run.At those concentrations there is no choking and no struggle. A few breaths and you dropwhere you stand. That is why the villages looked the way they did.Height was the whole difference. In Subum there was one two story building, a maternityclinic. The women and newborns on the upper floor lived. Most of the village did not.Two years earlier, a smaller lake ninety five kilometers away had done the same thing andkilled thirty seven people. A volcanologist worked out exactly what had happened and wroteit up. The science was right, and it was in hand two years early. It never reached anyoneliving around Nyos.There is one more thing, and it is the reason scientists still talk about this.The magma never stops. The lake started refilling the moment it emptied. Today threepipes stand on the surface, venting it slowly and permanently, because if they ever stopit will happen again.And Nyos was the small one. Lake Kivu, on the Rwanda and DRC border, is the same kind oflake, thousands of times larger, with two million people living on its shores.

In September of 1900, Galveston's chief weatherman drove down to the beach to watch the morning tide. For nine years he had assured his city, in print, that a hurricane could never seriously harm it. By nightfall his house would be gone, his pregnant wife would be dead, and he would be clinging to his youngest daughter on a raft of wreckage in the dark. This is the horrifying story of the 1900 Galveston Hurricane, and as always, viewer discretion is advised.

On the morning of December 6th, 1917, a burning ship drifted into a Canadian harbour, and a crowd gathered along the waterfront to watch it. What almost none of them knew was that the vessel in front of them wasn't an ordinary freighter — and that within seconds, the city behind them would be gone. Viewer discretion is advised.