SANTIAGO (Bloomberg) — The volcano that has erupted in southern Chile for the first time in 9,000 years is causing a special problem for North Face Inc. founder Douglas Tompkins and his wife Kristine. They own it.

The Chaiten volcano sits on the southern edge of Pumalin Park, a 300,000-hectare (740,000-acre) reserve that the Tompkinses have spent $50 million on in a bid to preserve a swath of Patagonian rain forest. Ash and rivers swollen by volcanic mud have ravaged land, trees and trails on a third of the park and threaten to obliterate 17 years of work, Kristine Tompkins said.

"It's a mess, a serious mess," she said in a May 13 phone interview from Pumalin's administration centre at Puerto Varas, about 160 kilometres (100 miles) from the volcano. "If it gets worse, it could hammer in a big way the infrastructure we've built, and wipe out forests that'll take thousands of years to return."

The eruption has spewed windblown ash east across the Andes as far as Buenos Aires, almost 1,500 kilometres away, and forced the evacuation of more than 4,000 people living within a 30-kilometre radius of the mountain. A 3,000-year-old hardwood forest of evergreen Alerce trees has been spared so far.

About 90 percent of the now-evacuated town of Chaiten is flooded, Chile's national emergency office said last Thursday. Residents probably won't be able to return for at least three months, Chilean Defence Minister Jose Goni said the same day.

Douglas Tompkins was traveling and unavailable for comment, Pumalin spokeswoman Carolina Morgado said. In an interview with Bloomberg News last year, Tompkins, now 65, recounted the steps that led him to Chile

He said he first visited Patagonia, a vast expanse of mountains, rivers and grasslands at the southern tip of South America, in the 1960s. A climbing buddy with him on that trip later started Patagonia Inc., the outdoor-apparel company where his present wife once served as chief executive officer.

Tompkins himself went on to found and sell outdoor-gear maker North Face in the 1960s. In 1968, he started fashion company Esprit Holdings Ltd. with his first wife. He gave up his Esprit holdings for $200 million in 1989.

Two years later, he sold his Ferrari and Amish-quilt collection and moved to an isolated cabin in Chile to work fulltime on conservation. He married Kristine, a long-time friend, in 1993. They say they have spent $200 million to acquire and preserve 810,000 hectares of land in Chile and neighbouring Argentina.

Pumalin, which spans the country from Argentina on the east to the Pacific Ocean on the west, is the showcase of their holdings. Its self-guided trails, rustically luxurious cabins and elegant visitors' centre draw 7,000 visitors a year. In 2005, the Chilean government granted the park the status of a nature sanctuary.

Since the eruption, the Tompkinses have relocated 75 people who live and work in the reserve. Kristine Tompkins said fly-overs showed that flooded, debris-filled rivers threatened to wipe out livestock on several farms that they own contiguous to the park, which is owned by a foundation established by the couple.

"We're anticipating major damage," Kristine Tompkins, 57, said. "What's shocking is that this thing is still blowing as hard as it was the first day and we don't know what will happen next."

The eruption is refocusing attention on the Tompkins holdings and stirring up old controversies.

Douglas Tompkins, who says he is a proponent of so-called Deep Ecology, a philosophy that blames technology from laptop computers to nuclear power plants for damaging the environment, has upset local officials and business people by refusing to allow logging, hydroelectric dams and a proposed roadway through his reserve.

President Michelle Bachelet's government announced May 8 it would ban all land purchases in the area hit by the volcano, after local officials said they were concerned that Tompkins would try to take advantage of the eruption to buy out farmers whose livelihood could be wiped out.