Key Takeaways
- All nine victims of the Feb. 17 Castle Peak avalanche died of asphyxia, according to the Nevada County Coroner's Office.
- Victims were buried 5 to 8 feet below the surface, making survival highly unlikely.
- The group included three Blackbird Mountain Guides and six clients; five others survived.
- A Sierra Avalanche Center report said the guides led skiers into dangerous avalanche terrain.
- The Nevada County Sheriff's Office is conducting a criminal investigation.
Introduction
Months after a deadly avalanche swept through backcountry terrain near Truckee, the Nevada County Coroner's Office has released its findings. All nine people killed by the Feb. 17 Castle Peak slide died of asphyxia after being buried under snow.
Coroner's Findings on the Castle Peak Slide
Partially redacted reports released Thursday, Aug. 6, show each victim died from asphyxia due to snow burial, according to the San Francisco Chronicle. The cause of the avalanche and the decision-making by guides remain under scrutiny. The coroner reports recapped the rescue and recovery efforts but provided few new details.
Why Asphyxia Is So Deadly
Asphyxiation occurs when the body does not receive enough oxygen. In avalanches, it can happen when snow blocks the airway, when heavy snow prevents the chest from expanding, or when a person rebreathes exhaled air in a confined space.
Asphyxiation is the leading cause of avalanche fatalities. One study found it accounts for 75% of fatalities.
Burial depth plays a critical role. Victims buried deeper than two meters (about 6.5 feet) have a survival probability of only 10%, while those buried less than half a meter (about 1.5 feet) have an 80% survival rate. The Castle Peak victims were buried between 5 and 8 feet deep.
Victims and Rescue
Most of the dead were Bay Area women on a ski trip who had spent days at the nearby Frog Lake huts. The dead included three guides from Blackbird Mountain Guides and six clients. One guide and four clients avoided the falling snow and survived. Several members of the group wore avalanche airbag backpacks, but none of the devices deployed, according to researchers.
Investigation and Scrutiny
The Nevada County Sheriff's Office launched a criminal investigation. A report by the Sierra Avalanche Center concluded the guides led the skiers below avalanche terrain during dangerous conditions and traveled in a group large enough to potentially trigger the slide.
Local California Context
The avalanche occurred on Castle Peak, northwest of Truckee in Nevada County. The victims were part of the Bay Area backcountry community, and the incident became the deadliest avalanche in modern California history. The surrounding Tahoe National Forest remains a popular winter destination, but this tragedy underscored the risks of traveling through avalanche terrain during winter storms.
Background
On Feb. 17, a 100-foot-wide wall of snow cascaded 400 feet down the mountain onto the group during a blizzard. The skiers had been staying at the Frog Lake huts. Investigators are still looking into why the group left the safety of the huts despite hazardous conditions.
Conclusion
The coroner's reports confirm the cause of death but leave larger questions unanswered. Skiers and riders heading into avalanche terrain should check forecasts, carry proper gear, and understand that burial depth can determine survival. Until full reports are released or the sheriff's investigation concludes, the backcountry community is left to mourn and learn from California's deadliest avalanche.