By Michael Lanza
We have just begun our all-day hike over some of the volcanoes of New Zealand’s Tongariro National Park when a trailside sign conveniently itemizes the life-threatening hazards awaiting us.
For starters, an eruption could eject large rocks into the air to rain onto us from the sky or release lava flows. Pyroclastic flows, which are clouds of ash, rock, and gas that can cook flesh, could come upon us at 60 mph. Just such a flow in 1975, in fact, formed the black rocks we’re standing on. Even short of a volcanic eruption, deadly volcanic gases can pool in the bottom of craters on calm, sunny days like today. And the rock on these peaks is so unstable that falling rock looms as a constant hazard.
Should we notice any signs of an eruption—an earthquake, for instance, or an ash cloud, or that other telltale indicator, rocks flying incongruously through the air—we should “move as quickly as possible down off the mountain.”
Yea, sound advice. In theory, anyway.
I find the sign rather comforting, actually: Before exploring a new place, I like knowing what could kill me there.
The warnings are not hyperbolic. Tongariro National Park looks like a place recently devastated by a very big bomb—which is, in a sense, what happened. The first volcano we will climb, Mt. Ngauruhoe, erupted 45 times in the 20th century. Red Crater, also on our itinerary today, last erupted about 130 years ago—an eye blink in geologic time. Mt. Ruapehu, dominating the horizon just a few miles to the south of Ngauruhoe, ranks among the world’s most active volcanoes. Blowing its top with a major eruption roughly every 50 years for at least the past 250 millennia—including in 1895, 1945, and 1995-1996—Ruapehu has also experienced at least 60 “minor” eruptions since 1945, some of which produced ash falls and lahars, which are deadly flows of mud and rock.
Sounds like very serious stuff.
I’m spending the day hiking a 12.1-mile loop over three of the main volcanoes and craters of Tongariro, in the center of New Zealand’s North Island. Established in 1887—just five years after Yellowstone became the world’s first national park—Tongariro was New Zealand’s first national park and the world’s fourth. It is also a dual World Heritage area, recognized both for its importance to the culture of the Maori, the original people of these islands, and for its natural values. Besides prolific volcanism and associated natural features, the national park is known for its strikingly stark, colorful landscape.
Although nearly devoid of plant life—we won’t see a single tree or bush all day, or any flora taller than scattered clumps of grasses and alpine wildflowers—the volcanoes have birthed a Technicolor world of craters painted in vivid shades of burnt red, orange, brilliant white, gray, deep black, yellow, and brown.
My companion today, Stewart Barclay, a local trekking guide with who comes up here several times a week almost year-round, has graciously offered to take me on a hiking tour. Our route will deviate somewhat from the course of the 12-mile (19.4k) Tongariro Alpine Crossing, often referred to as New Zealand’s finest dayhike; it is probably this country’s most popular single-day tramp. Like some famous U.S. hikes—such as Yosemite’s Mist Trail or New Hampshire’s Presidential Range—the Tongariro Alpine Crossing attracts hundreds of people on summer days when the sun shines, which is far from a sure bet in these famously stormy islands.
We’ve drawn good cards with regard to the weather: While Stewart had advised that we abandon our plans if the skies looked threatening this morning—Tongariro’s volcanoes are notorious for high winds, heavy rain, and fog that obscures visibility—we have set out under a deep-blue sky, wearing T-shirt and shorts on this February austral-summer day.
And we’re cautiously optimistic that statistical probability is on our side, and that the turbulent earth beneath these peaks will not misbehave in any of the ways described on that trailside sign today.
About 40 minutes into our hike, following the wide, well-constructed trail of the Tongariro Alpine Crossing up the valley of Mangatepopo Stream, Stewart points out its source—Soda Springs, where clean, cold, sulfurous water pours from the ground, reeking of rotten eggs. The stream had long been a boggy area until a month ago, when localized thunderstorms triggered a lahar that reamed out the streambed. The natural disaster acted as a sort of flash-flood beautification project: the area is much prettier now, Stewart tells me.
Perhaps more than anyplace I’ve ever seen, Tongariro looks truly like the surface of the Moon. Black rocks lie strewn across dusty ground of pebbles and loose volcanic dirt. Hiking up the Devil’s Staircase, a climb of 1,000 vertical feet from the Mangatepopo Valley to the saddle between Mts. Tongariro and Ngauruhoe, we walk through old lava flows—heaps of coal-black rocks and boulders with razor-sharp edges. Here and there, grass sprouts and gentians bloom amid the otherwise lifeless terrain. Besides a few birds, we see no animals out here.
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At the saddle, at an elevation of almost 5,400 feet (1,640 meters), we pause to look at our route up Mt. Ngauruhoe (pronounced “Nau-ra-HO-ee”). It’s hard not to be impressed. The mountain forms a classically conical volcanic peak, owing to it being much younger than neighboring Tongariro and Ruapehu; those volcanoes have experienced many more eruptions, forming new craters, deforming their original cones. Ngauruhoe’s plume, or vent, is only 2,500 years old; Mt. Tongariro is 300,000 years old.
We can see the ant-like figures of perhaps two dozen other people slowly picking their way up the mountain’s north slope. Ngauruhoe is a side trip off the traditional route of the Tongariro Alpine Crossing—an ascent that most hikers pass on because of its steepness and loose rock, which make the 2,100-foot, off-trail scramble both strenuous and hazardous. The slopes of volcanoes are among the least firma of all terra on the planet. On a steep one like Ngauruhoe, it’s basically impossible for even the most careful hiker to avoid sending some of the pumice-like tephra rocks tumbling downhill.
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Stewart and I start upward, choosing a line far to the left of where most of the people above us are ascending or descending. The ground slides away beneath our feet with most steps upward; at times, I step higher only to end up farther downhill. Frequently, we scramble on all fours, clinging to the mountain. The final 300 vertical feet to the crater rim, clawing up a hill of dusty ash and crumbling stone, simulates climbing a giant, absurdly steep sand dune.
At the rim, at 7,516 feet (2,291 meters), we stand at the brink of multi-colored cliffs dropping about 300 feet into the rubble-strewn crater bottom. The round crater spans more than 600 feet across. With just a few clouds swirling around us, we can see the park’s several craters and Mts. Tongariro and Ruapehu, as well as several lakes. Of Ruapehu’s three named summits, Tahurangi, at 7,536 feet (2,797 meters), is the highest point on the North Island. Far to the west, the largest lake in New Zealand at 238 square miles (616 square kilometers, or slightly smaller than Utah’s Lake Powell reservoir), Lake Taupo, glitters in the sunlight.
Stewart and I take a victory lap around the crater rim in a cool breeze, then descend about 300 vertical feet to a ridge that comprises the extant outer rim of the volcano. Steam issues from several fumaroles, vents boring deep into the earth. Hot lava near the Earth’s surface, right beneath us, creates this scalding steam, Stewart explains.
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