ANCHORAGE, Alaska (AP) -- A huge landslide down a remote peak in Alaska caught the attention of scientists because it registered on seismographs around the world.

"The rock slide is indeed enormous, but I think the thing that's really unusual is the seismic signal is much larger than what you'd expect," said seismologist Jackie Caplan-Auerbach with the Alaska Volcano Observatory. "We're still trying to figure out why."

The slide shook the earth with as much vigor as a magnitude 3.8 quake and dumped an estimated 65 million cubic yards of rock and ice from the south face of 10,500-foot Mount Steller on Sept. 14. The mountain is about 240 miles east of Anchorage south of Wrangell-Saint Elias National Park in the eastern Chugach Mountains.

The landslide registered on instruments across the world, said seismologist Natasha Ruppert with the Alaska Earthquake Information Center in Fairbanks.

"I've never seen anything like this, and what surprised me is how huge it was," Ruppert said. "It's more like an explosion, I would say, than an earthquake. It hit the ground and seismic waves traveled in all directions."

It's not clear what triggered the release, the scientists said. It wasn't caused by an earthquake. No one knows if warming climate could have weakened ice holding the mountain together -- blamed for several landslides in the Alps.

"Someone would have to go there and see what kind of rocks were involved in this slide, if they were water saturated," Ruppert said.

Mountain ranges like the Chugach are perpetually crumbling, near a "state of failure" anyway, noted research geologist Peter Haeussler, with the U.S. Geological Survey in Anchorage.

"This was a big slide, but the rocks are weak, the slopes are steep, so I don't see that you need to invoke a climate change origin to this one," he said in an e-mail message.