A Journey to an Active Andesite Stratovolcano – White Island

On clear days we see it far offshore, a tiny smudge of an island with a plume of mist trailing above it—White Island.

We knew it was an active volcanic island, and that special boat tours took people out there, and that you don hard hats and gas masks and walk around amidst sulfur-gas-spitting vents. What was it like to be on an active volcanic island? Finally, we decided we had to go.

White Island is located 30 miles offshore from Whakatane on the North Island of New Zealand. It is New Zealand’s most active volcano. The word “active” is no exaggeration. White Island is one of several volcanoes in New Zealand that could have a major eruption at any time.

White Island (1)

Captain Cook named it White Island in 1769 because it was shrouded in white cloud, not realizing that it was a volcano at the time.

Actually when you see White Island, you are only seeing the top of a huge submarine mountain rising 5,249 feet—almost a mile—above the sea floor. Built up by volcanic activity over the past 150,000 years, the island itself is about 1.2 miles in diameter, roughly circular in shape, and at its peak rises 1,053 feet above the sea level.

Taupo Volcanic Zone

White Island is part of the Taupo Volcanic Zone (TVZ), an area of active volcanic activity extending from White Island to Mount Ruapehu, another large active volcano in the center of the North Island. This band of active volcanic activity is approximately 217 miles long and 31 miles wide, and is classified as extremely active on a world scale.

Taupo Volcanic Zone (2)

Geologically, this is part of where the giant Pacific tectonic plate is being forced under the giant Australian tectonic plate. The earth’s crust doesn’t like this. The entire area is prone to earthquakes and volcanic eruptions. Volcanic activity is constantly occurring in the TVZ including in the past year and a half since we’ve been here.

Subduction of tectonic plates (3)

A Little About Volcanoes . . . But Not Too Much

Geologists generally classify volcanoes into one of four types: stratovolcanoes, shield volcanoes, cinder cones, and lava domes.

White Island is a stratovolcano, also called a composite volcano. These type volcanoes are characterized by their steep sides and periodic explosive eruptions. Lava, hot gases, cinders and ash erupt from a central crater or series of vents. Over time, these materials accumulate around the central crater, growing upward and giving stratovolcanoes what we tend to think of as a classic volcano appearance.

The famed Vesuvius in ancient times and Mount Saint Helens and Mount Pinatubo in modern times are examples of stratovolcanoes.

Volcanoes can also be classified by the type of lava they produce, or, more specifically, the characteristic igneous rock that the lava hardens into. Molten rock beneath the earth’s surface is called magma. When magma reaches the surface or erupts from a volcano, it is then called lava. Lava cools and hardens into rock. Stratovolcanoes often produce lava in the mid-range in terms of temperature and viscosity. This lava cools relatively quickly and doesn’t flow for miles and miles, and commonly hardens into a rock called andesite. Much of the volcanic rock on White Island is andesite.

Hence, based on all of the above criteria, White Island can be termed an active andesite stratovolcano. It is currently continuously monitored with cameras and numerous seismographic and other scientific instruments. On the day of our trip, the volcanic alert level was “1”, termed “minor volcanic unrest.” (Website listing White Island’s current volcanic status http://www.geonet.org.nz/volcano/info/whiteisland).

Here is a list of recent significant White Island volcanic activity:

1981-1983 – major eruptions changed landscape and destroyed forest that had been present
July 27, 2000 – an eruption blanketed the island with mud and scoria (a type of volcanic debris)
August 5, 2012 – minor eruption
August 20, 2012 – minor eruption

Our Trip to White Island

In the past, anyone could apparently just land on White Island and look around. Currently, the island is privately owned and also designated as a marine reserve. Permission is needed to land on White Island.

We meet at the offices of White Island Tours in Whakatane in the early morning along with some fifty other travelers. It is an hour-and-a-half boat ride out to the island, then we will be transferred from our larger boat and ferried to shore on a small inflatable motor boat. After a two-hour guided tour on the island itself, we will return to Whakatane. Lunch is included.

The first thing we do is to read and sign a waiver. It starts off saying, “Any venture involving the sea or a live volcano has risk.” And then continues, basically saying, “Hey look, you’re going out to sea on a small boat and are then going to take a smaller inflatable boat onto an active volcanic island. You can fall into the water and drown. There are poisonous gases on the island. In fact, the whole thing could potentially blow up at any time. If anything goes wrong, we warned you and this is New Zealand, don’t expect to sue anyone.” The exact quote for that last part is “Warning: Under New Zealand law it is extremely unlikely that you will be able to sue anyone if you are injured.

The captain and crew are dressed in purple-striped shirts looking at bit like Gilligan in the old TV series.

The skipper.

At first, when we leave Whakatane Harbor, we can’t even see White Island. Then as we surge forward, it slowly emerges out of the morning mist.

As time passes, the island grows ever more distinct. It looks mysterious and a bit foreboding, I feel like I’m heading toward Skull Island, the famed fictional island on which King Kong lived.

Eventually, steep rocky cliffs stand out in sharp relief against the blue sea, with white splotches on the cliffs where large colonies of gannets, a type of seabird, make their homes. A huge plume of smoke rises from the central portion of the island.

After circling the island, we pull into a bay and the engine burbles to a stop, the craft swaying gently in the currrent. The bay is the entry point to the huge central crater region where we will be walking.

Onboard, we are given hard hats that are to be worn at all times once on shore, and after a brief ride to shore on the motorized rubber raft, we are divided into groups of about fifteen and given gas masks. The gas masks are for use when we are near some of the steaming vents or in case of sudden wind changes that might blow the gases in our faces.

The small bay where we are brought ashore.

White Island is a harsh environment. It looks like a harsh desert landscape except belching steam and yellow gases. To the best of my understanding, the ground—which feels warm under our feet—is a mixture of hardened ash, volcanic debris and lava. Some of this debris is what is termed scoria, our guide explains. Scoria is a particular type of lava rock that has lots of vesicles, or air pockets, in it. Commonly called simply lava rock, you might be most familiar with it as the landscaping rock you see at places such as Taco Bell in the United States. Lava rock is laying all over the ground on White Island.

Some of the volcanic monitoring equipment can be seen throughout the central crater region. We pass numerous smaller vents most of which puff sulfuric fumes—we put on our masks several times. Then we make a slight climb to reach the area of the central crater itself. Looking down into it, you see a lake of boiling water emitting clouds of steam. It is quite impressive. This is nature at its rawest. The whole area just looks unstable.

We continue down stopping at a boiling mud pot and a stream of acidic, hot water. Finally, we arrive back near the bay again. Here are the remains of an old factory. On four separate occasions, sulfur was mined on White Island: in the mid 1880s, from 1898-1901, from 1913-1914, and in 1923.

Mining in late 1920s on white island Alexander Turnbull Library, Mabel Rosser Collection (PAColl-2668) Reference: 1/4-059931; F

Mining in late 1920s on White Island (4)

The sulfur mined on White Island was used as an antibacterial agent, including as a sterilizing agent for wine corks, to make match heads, and finally in later years for fertilizer.

White Island is a harsh environment. All supplies for the miners and the factory had to be transported out from the mainland. A small factory was constructed on the island where the sulfur diggings, after being transported on small rail trucks, were crushed and bagged for shipment.

In 1914, part of the western crater near the camp collapsed and a lahar, a debris flow, killed all ten workers on the island.

Remains of old sulfur factory.

An interesting piece of trivia is that only the camp cat survived the tragedy. He was named “Peter the Great” and according to our guide went on to sire numerous kittens, considered to be lucky cats, back in the town of Opotiki on the North Island.

(5)

In the 1923 mining attempt, the camp was placed on a safer, flatter part of the island, away from the central crater region. The miners would row their boats around to the mining area every day. Soon after, however, sulfur mining on White Island became unprofitable, and the sulfur mining operation was abandoned. The island has remained uninhabited since that time.

Machinery corroded by toxic fumes.

Walls and roof beams from the old factory still exist. What remains of the old machinery is badly corroded from the harsh sulfuric fumes.

Once back on the boat, we are given a box lunch. After eating, everyone half-dozes on the way back to Whakatane. The steady hum of the boat’s screws lulls one to sleep.

Leaving White Island.

What do I think? What comes to mind for me from the whole experience is that the earth is alive. Perhaps it sounds trite, but I think of the famed quote that says that geologic time is now. We often tend to think that geologic events are only things that occurred millions of years ago, or are things that we read about it books, while the truth is that these same processes are going on right now—literally right beneath our feet. White Island tells that story.

Finally, here’s a short, two-minute video of our journey.