Volcanoes:The complete guide

Where have you been lately? Since Mount Etna started blowing its top in mid-July, hordes of people have been flocking to the site to get a closer look, and hoteliers are reporting an increase rather than a decrease in bookings. Volcanoes are big business. The sight of molten lava and smoke and fire billowing out of the top of a crater – not to mention volcanic lightning – creates a mesmerising pyrotechnic show.

DOESN'T SOUND LIKE A GOOD HOLIDAY OPTION TO ME...

Where have you been lately? Since Mount Etna started blowing its top in mid-July, hordes of people have been flocking to the site to get a closer look, and hoteliers are reporting an increase rather than a decrease in bookings. Volcanoes are big business. The sight of molten lava and smoke and fire billowing out of the top of a crater – not to mention volcanic lightning – creates a mesmerising pyrotechnic show.

BUT AREN'T THEY DANGEROUS?

They can be, yes. There are around 550 active volcanoes in the world – that is, volcanoes that have erupted and are expected to do so again. However, they're regularly monitored for seismic activity, and usually volcanologists are able to give plenty of warning – although tell that to the Philippine villagers living in the shadow of the Mayon Volcano. Tens of thousands had to flee from the area 200 miles south of Manila when it erupted for the second time in as many months at the end of July. Scientists who had been monitoring the volcano realised it was about to blow less than four hours before the eruption.

Etna's latest activity has caused some inconvenience to those living in the immediate vicinity and tourists trying to holiday on Sicily, but its effects have not, so far, been life-threatening. Unless you count ash on the runway, of course – the volcanic equivalent of leaves on the lines. Catania Airport has been forced to close on a number of occasions, and planes diverted to Palermo, as it was thought that ash and cinders might get into the engines and cause a hazard for the aircraft.

Before it started its latest rumblings, you could take a cable car or four-wheel drive up to the main crater to explore the lava flows and ash-fields. Now the resort of Rifugio Sapienza is minus its ski lifts and holding its breath to see whether the man-made barriers will withstand the forces of nature or whether it will be totally obliterated.

HOW ARE VOLCANOES CREATED?

Volcanoes are created by plate tectonics. The earth is covered with a series of giant slabs that rub alongside each other, occasionally colliding with violent results – that is, earthquakes and volcanic eruptions. There are two types of plate movement. When plates converge one is forced below the other. The descending plate starts to melt and form magma (liquid rock) which, as it is less dense than the surrounding rock, rises to the surface, breaking through the Earth's crust to form a volcano. Converging plates create classic, cone-shaped volcanoes called stratovolcanoes. Plates that are separating allow hot rock from below the Earth's crust to surface, often under the ocean, creating shield volcanoes with gentle slopes. "Hotspots" or gaps in the earth's crust also cause volcanoes, often creating an island chain such as Hawaii.

AND WHERE ARE THEY?

All over the world, along the plate boundaries, mostly within what is known as the Ring of Fire. This is an arc stretching around the Pacific Ocean (following the border of the Pacific plate) from South America up the coast of North America to Alaska's Aleutian islands and then down the Asian coast to New Zealand. The Ring of Fire contains 75 per cent of the world's active and dormant volcanoes. Indonesia alone is home to 130 active volcanoes, more than any other country in the world.

SO WHAT HAPPENS WHEN A VOLCANO BLOWS ITS TOP?

Check out the account by Pliny the Younger. He wrote a vivid description of the most famous volcanic eruption of all time. When Vesuvius erupted in AD79, burying Pompeii and Herculaneum, he was about 18 miles away with a bird's-eye view. In the two letters he wrote after the event he described the earthquakes preceding the eruption, the huge vertical column of black smoke, ash and debris, and the pyroclastic flow. In fact, it was the latter that was responsible for killing the people of Pompeii. During the eruption ash rained down on the city six miles to the south-east of the crater at a rate of between six and eight inches per hour.

However, the worst was yet to come. A volcanic cloud, estimated at about 12 miles high, was held aloft by the sheer force emanating from the volcano. When that abated briefly, this cloud of burning ash and gases (about 750F, or 400C), followed by a denser cloud of volcanic rock and debris started rolling down the mountain and literally blasted through Pompeii. Generally lava (molten rock or magma from inside the earth mixed with gases and steam) is also spewed from the crater and flows down the slopes of the volcano, destroying everything in its path. The speed of the flow varies, depending on viscosity and the steepness of the volcano slopes and can range from 1mph to nearly 20mph. The lava can be anything from 1,300-2,200F (705C-1,200C) and takes up to a year to cool.

ANY OTHER HAZARDS?

Tsunami or tidal waves occur as a direct result of the seismic activity on the sea floor. An eruption around 1545BC on Santorini, the only active volcano in southern Europe outside Italy, caused a tidal wave which is believed to have wiped out the Minoan civilisation on Crete over 70 miles away. The event gave rise to the legend of the lost continent of Atlantis in Greek mythology. In the early 1990s in Nicaragua, Indonesia and Japan, tsunamis caused widespread destruction and killed about 2,000 people. And then there are lahars, or mudslides... should I go on?

YOU'RE REALLY SELLING THIS TO ME

Most volcanoes are slumbering giants – honestly. Reports out of Sicily over the last month have shown how attached the locals are to their mountain. Trips to areas of volcanic activity usually focus on the results of past activity (walking over weird lava moonscapes) or viewing present fireworks from a safe distance. Take Volcanic Experiences (01527 832578, www.volcanic-experiences.co.uk), for example, which offers a number of geologist-led trips to areas of volcanic interest including Santorini, southern Italy and the Aeolian islands and Iceland. The eight-day trip to Iceland includes excursions to the Pingvellir National Park (where a series of deep rifts disgorged basalt lava), the Viking settlement buried by an eruption of Hekla in 1104 in the Pjorsdalur valley and unearthed in 1939, and Landmannalaugar's green and red rhyolite peaks, lava flows, steam vents and hot springs. The cost is £875 per person including half-board accommodation, flights and transfers. The eight-day trip to Sicily and the Aeolian Islands takes in Mount Etna (although the next trip is not scheduled until May 2002), views the night-time fireworks on Stromboli and includes a walk around the crater rim at the summit of Vulcano. (The word volcano is derived from Vulcan, the Roman God of fire). The cost is £635 including flights, half-board accommodation and coach transfers.

SOUNDS A BIT DRY. IS THE FOCUS ALWAYS ON GEOLOGY AND ARCHAEOLOGY?

Not at all. Many trips are more adventure-led than academic and include activities such as kayaking, white-water rafting, horse riding and mountain biking in conjunction with climbing a volcano. In Pucon, a village in the Chilean Lake District where the emphasis is firmly on outdoor activities, you can climb the active Mount Villarica. Tucan (020-8896 1600, www.tucantravel.com) runs a 28-day trip called Patagonian Lakes which includes the climb as an optional activity. Led by a local guide, you're kitted out in protective overalls with ice picks and crampons and an oxygen mask for use at the top. It's a full-day hike, at first on loose scree and later across packed ice. The four-week trip costs £2,240 including accommodation, ground transport and three internal flights. Fares to Santiago are extra, as is the climb (£28.50)

Explore Worldwide (01252 760 000, www.exploreworldwide.com) offers a 14-day trip to the Cape Verde Islands, a volcanic archipelago just off the coast of West Africa. The trip includes an optional ascent to the summit of the volcano, Pico de Fogo (9,281ft). Fogo last erupted in 1995. The volcanic activity has rendered the soil particularly fertile. Grapes and coffee are two of the crops to benefit. Two nights are spent in the village of Cha das Caldeiras, a village actually inside the crater, where the houses are built from volcanic rock. The trip costs from £1,125 per person and includes flights and accommodation.

WHAT OTHER PEAKS CAN I SCALE?

How about Cotopaxi in Ecuador? Tim Best Travel (020-7591 0300, www.timbesttravel.com) offers a 14-day all-inclusive trip to Ecuador's Avenue of the Volcanoes. The central valley south of the capital, Quito, is peppered with over 30 volcanoes. Eight are active, including Cotopaxi, which at 19,344ft is the second highest active volcano in the world (the highest is Guallatiri in Chile at 19,876ft). The area around Cotopaxi is a national park ideal for hiking, while the central valley is scattered with Indian villages and markets. If you want to climb Cotopaxi itself, the ground handlers can arrange it for an additional fee. The price of the trip is £3,124 per person.

SOUNDS TAXING

It doesn't have to be. Volcano-watching can be part of a luxury holiday. Take St Lucia, for example. You can drive to a car park in a collapsed crater and visit the hot sulphur springs. Staying in the famous Anse Chastanet (see Room Service, page 4), you can view the two famous volcanic peaks, the Pitons, from the comfort of your room. In Hawaii you can stay on Big Island at the Volcano Inn (00 1 800 997 2292, www.volcanoinn.com), just minutes from the active volcano, Kilauea, and take a helicopter ride to peer down inside a crater. Hawaii Air Tours (00 1 877 228 5954, www.hilowings.com) offers a number of options including the 45-minute Hilo Helicopter Volcano Tour, which costs $156.30 (about £111) per person. Flying over clouds of hydrogen sulphide gas produced as the lava enters the ocean, you also see red-hot, molten lava and areas of current volcanic activity.

AND IN PACKAGE HOLIDAY LAND...

Ever wondered about all that black sand? The Canaries are volcanic islands. Tenerife is home to the Teide volcano which last erupted in 1909. You can stay in a hotel, the Parador Canadas del Teide, in the crater (book through Keytel International: 020-7616 0300). Lanzarote has 300 volcanoes, one of which blew in 1730 and erupted continuously for the next six years, resulting in the stark lunar landscape that inspired artist César Manrique. His distinctive works incorporate the bizarre volcanic fall out – even his home was created from five volcanic bubbles.

JMC (0870 607 5085, www.jmc. com) has also just started trips to the Azores in the Atlantic Ocean. The new brochure features three hotels on the largest of the nine islands, Sao Miguel, which is dotted with crater lakes and boiling mud pools. Prices start from £759 per person for seven nights including return flights via Lisbon and B&B accommodation.

STILL ALL SOUNDS A LITTLE CLOSE FOR COMFORT...

If you don't feel you can face the real thing, why not pop along to Europe's first volcano park? Vulcania will open in spring 2002 in the Auvergne region of France (00 33 4 7331 02 05, www.vulcania. tm.fr). This sculpted park takes you into a lava tunnel, where you come face to face with a molten lava flow, and interactive exhibits allow you to gaze over the edge of a crater to see the churning mass below. The cost will be adults Fr118 (£11), children aged 5-16 Fr78 (£7.50).

FROM THE top of the track the volcano rose up like a large anthill beside the lime green lake. Small figures clambered up one side, recognisably human, and down the other metamorphosed into creatures from the bog. Volcan del Totumo is a miniature volcano, about an hour by bus from Cartagena on the Colombian Caribbean, which spews up mud instead of lava. Legend has it that the volcano used to breathe fire, until a local priest, believing it the work of Satan, sprinkled it with holy water. The flames were extinguished and turned instead to mud to drown the devil.

There are mud volcanoes all along the Caribbean coast of Colombia, some just bubbling fissures in the ground, but El Totumo is one of the largest in the world at 50ft high. Mud volcanoes are created by sulphurous gas emissions from decaying vegetation underground. The gas pushes the mud up through the ground, forming a conical mound. The volcano continues to grow as long as more mud is being forced upwards over the rim of the crater.

Paying my $2, I climbed the rickety steps to a wooden platform and eyed the mudbath warily. The mineral-based mud is supposed to have therapeutic properties. Looking down into the crater I gazed at the thick, grey soup the consistency of condensed milk. The pale sludge was between one and two thousand metres deep: a bottomless pit full of slime. I eased myself on to the ladder, slippery with sludge. As I let go, arms pulled me into the centre of the glutinous ooze. The mud was warm and smooth and smelled of sulphur. Floating on a dense mass of slime, rolling over and lying on my back, I felt like a hippopotamus in heaven.

Later, clambering down the side of the volcano I squelched over to the lake where local women were waiting to wash away the hardening crust.