USGS believes 'seismic signals' related to rock slide in Rocky Mountain National Park

A rock slide has closed a portion of Rocky Mountain National Park. The slide happened in the Upper Chaos Canyon area of the park on Tuesday and there is an investigation into what caused it. 

The photo from Google Earth shows several outcrops on the south shoulder of Hallett Peak that came down about 4:30 p.m. Tuesday. Rainstorms are predicted in the forecast for the area through July 3 which may contribute to additional rock fall activity. No one was injured. 

The U.S. Geological Survey says the slide was "preceded ~100 seconds earlier by a M1.5 earthquake-like signal located at or near the surface in the area where the landslide occurred."

"There are actually two seismic signals associated with the landslide. The sequence stared with what looks like a really small earthquake and then about 100 seconds later there's a second, more gradual rumbly signal that looks a lot more like the type of signal we see from landslides similar to what was caught on video," said Kate Allstadt with the USGS in Golden. 

RMNP closed all areas of Chaos Canyon to the west of Lake Haiyaha to all users due to the rock fall activity and potential impacts. the closure will remain in effect until the projected rainstorms pass and the slope can be evaluated by National Park Service geologists. 

Scientists say alternatively "sudden rockfalls with significant free-fall can generate signals that look like shallow earthquakes."  

"So we do think that they are related. The earthquake was quite small in magnitude, 1.5, so you wouldn't even feel that if you were standing right on top of it. So, it's pretty unlikely, though not impossible, that the earthquake triggered the landslide. But what we think is more likely is that the earthquake actually reflects some information about the initiation of this landslide," said Allstadt. 

Additional Information from RMNP:

The hiking trail to Lake Haiyaha, Lake Haiyaha itself, and hiking trails on the north side of Hallett Peak remain open. The bouldering area in lower Chaos Canyon, on the north and east shore of Lake Haiyaha, will remain open.

Park visitors planning to recreate in rocky terrain areas of the park are reminded to always practice due diligence and use caution. Rocky slopes on and near mountain peaks can be unstable. Recreation users should know their own limits and choose routes that are within the abilities of everyone in their party.

For additional information on Rocky Mountain National Park, visit www.nps.gov/romo or call the park's Information Office at (970) 586-1206.