The famed hot springs of Haida Gwaii have gone dry, apparently a casualty of last week's major earthquake.

Parks Canada officials at Gwaii Haanas National Park Reserve and Haida Heritage Site said all four of the popular geothermal pools are empty.

It's not yet known whether the source of underground hot water has been permanently cut off or whether the loss is temporary.

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Hot springs are normally found near fault lines, such as the Queen Charlotte Fault, the site of Saturday's 7.7-magnitude earthquake. The springs are created when groundwater, heated by geothermal energy beneath the earth's surface, escapes to the surface through the cracks in the bedrock along a fault.

According to Brent Ward, an earth sciences professor at Simon Fraser University, the earthquake could have caused one of a number of subterranean changes that would make the hot springs go dry. These include changing the groundwater level, completely closing of the cracks the water used to reach the surface, or causing a sudden surge in water that depleted the underground reservoir for a short time. It's also possible the hot water was diverted elsewhere.

"We don't know if it's going to come back. We certainly can hope," Ward said. "In many hydrothermal areas, there's just a hiatus and then the hot water re-establishes itself."

Dozens of aftershocks, some as strong as magnitude 6.3, followed Saturday night's earthquake 74 kilometres south-southwest of Queen Charlotte City. Either the initial quake or one of the aftershocks could have caused the hot springs to run dry, Ward said.

Ernie Gladstone, the field superintendent at Gwaii Haanas, said on Thursday that one aftershock struck only a kilometre from the hot springs.

He and other Parks Canada staff travelled to Hot Spring Island, known as Gandll K'in Gwaay. yaay to the Haida, on Wednesday to confirm rumours of the springs running dry. Rising steam can usually be seen by boats approaching the shore, but not this time.

"The pools are completely dry. Normally the rock around the pools is quite warm, and was cold to touch," Gladstone said. "It was quite disturbing to go ashore to see there was no water in the pools."

He said parks staff are working with the Geological Survey of Canada to determine whether the hot springs loss is permanent.

The 15-hectare island is only accessible by boat, and is the destination for various sightseeing and tour companies from across the region. Three of the four pools are open to visitors to use.

All are dry, which is something Gladstone said he's never seen before, having bathed in the pools himself for the last 30 years.

"(But) there are certainly stories, oral history-type stories, of the flow changing during certain periods in the past," he said.

Goetz Tassilo Hanisch stopped at the hot springs at dusk Wednesday as he passed by on the way from Queen Charlotte City to his home in Rose Harbour. He was surprised to see no water.

"I went around in the moonlight listening because you can usually hear the water come out of the ground in the various cracks and springs, but nothing could be heard," he said by phone Thursday. He checked again in the morning and found only dried green mud.

Some of the rocks were still slightly warm, "whatever that means," he said.

Gladstone said loss of the hot springs would be "significant" for visitors and locals alike. About 2,000 people visit the park each year.

"It's not the primary reason for visiting the area, but it's certainly a place where kayakers and boaters and locals from Haida Gwaii and commercial fishermen would stop by.... It's a very special place for local people."

Park staff had been to the hot springs as recently as last Thursday, when the pools were as full and warm as usual. The springs have a full-time presence of Haida Gwaii watchmen only during the peak summer months.

No other significant damage was reported from the quake.

The 26 totem poles that stand in the village of Nan Sdins in the Sgang Gwaay world heritage site were unharmed, Gladstone said.

zmcknight@vancouversun.com