Spinal Tap Main and Couloir

Saw slide debris from East Col and descended to meet a party of 3 next to debris. Proceeded to initiate a beacon search as debris appeared fresh. Found no signals. Took photos. Size estimated at size 3.5 (reasoning below). All measurements here are estimates. Two start zones with two merging slide paths, meeting at midpoint and again 150m before Circle Lake. The highest elevation slide, at 20m underneath Spinal Tap entrance, approx. 100m across at the convexity, slid looker's right to the Spinal Tap couloir, curving across skier's left descent from East Col, before meeting the lower slide path at Circle Lake. The lower slide: looker's left and 30m below the higher slide, also some ~100m across, slid and released the entire rocky face, extending significantly to looker's left. Using binoculars, crowns estimated at 1.5m on both slides. Debris piles measured up to 2.5m. Total width at estimated 400–500m, with length some 45% of Circle Lake, with debris length ranging close or exceeding to 700m+. Debris was piled with hard chunks approaching concrete density. The ice was cracked around Circle Lake with fissures down 3m+ (be careful!). Of note to travellers: the slide slid across the standard skier's right descent from East Col, and slid directly across and over most of Circle Lake, where many parties transition. It also slid directly across the standard uptrack to Body Bag Bowl. Look up! After exiting the zone to Body Bag Bowl, I called in to Blackcomb Patrol and was informed the slide had been skier triggered, remote, from a rider standing on the ridge, with no involvement. I also was informed a previous party had reported it in the morning, with estimated time of the slide at 10am. Was informed slide was 2.5 to 3. Size 3.5. From below the width and length can be appreciated, in part because it is not one, but two start zones produce two merging flows. The two flows appeared to collide with some violence, evidenced by large debris piles and the cracking of the lake ice. The debris pile is deep, wide, piled with hard blocks. The cliffs above have crowns of piled debris and rock has been exposed. The slide in its destructive potential is possibly closer to a 3.5+. Of note, prior to this incident I observed 4 snowboarders bootpacking up East Col without avalanche kit. I made every effort to discourage them. We have been receiving massive snowfall on suspect layers.. Thankfully, they chose the route out Body Bag Bowl from South Col. I was glad to see them exit safely. I chose to share knowledge of consequence with a party venturing into the backcountry unprepared, and after seeing the slide debris, was glad I did. Travel safely everyone. - tcV