Thank you for the great video. One thing I would find very helpful is a video about useing these tests, compression, ECT, Etc. in determining if a slope or aspect is safe. Often I can generate data, but using that data in a meaningful way can be difficult. I guess a set of hard fast rules would be helpful
Thank you for the very easy-to-understand video. There are many wonderful places in Japan's snowy mountains, and avalanche avoidance always accompanies them. I want to spend a safe skiing life with my ski friends by referring to this video.
@Rprecision: There are no hard, fast rules except "it depends". The biggest thing to remember is that a snowpit test is a tool providing you with one observation on one particular slope/aspect/location. But like Karl said in the video, the ECT is great because it will indicate whether conditions are conducive to propagation. Which, to me, whenever I get a sizeable slab to propagate with a cleanish shear, I tend to err on the conservative side and ski mellower slopes, different aspect etc...
Karl, I just listened to your avalanche hour podcast which brought me to this page. Thank you for all of your hard work. I was showing my girlfriend different types of pit tests today and she asked a couple of questions I hadn't thought about, but I'm now curious about. How did you determine the dimensions of the test block?
He has centimeter markings on his probes. Most probes will have this for this kind of reason and, more grimly, to allow you to establish depth of burial and therefore correct dig angle in a search situation. If you don't have that you can measure your arm (elbow to wrist or elbow to forearm) at home and use that to approximate. Standardizing is good (like getting very close to 30cmX90cm), but a reasonable approximation should have similar results.
Good vid, Karl. I note from one of your papers that this test is effective down to a depth of about 1 or maybe 1.3 meters. Have you guys been working on a method for assessing shear and propagation at greater depths? It's great to have such simple tests, but I wonder if using a standard mass (say, 1 liter water container) , dropped from particular heights onto the shovel, would make replication better and reduce the error bars that would be inherent to this method? Thanks for your work.
So would you ride on that slope? What is the rider's decision? If you get ECTP20+ is it considered to be stable enough? What is you lowest margin of ECT score that you would not ride?
+DimaFern Great question. The simplest answer is that even with a high score you should think twice about riding that slope since it propagated. You can imagine a slope where maybe the slab is thicker and requires 27 hits to get it to go, but maybe in a thinner spots near the edges of the slope you could release it with 15. In general, whenever we get propagation we are worried.
+AvalancheGuys Thank's for the answer. I understand what you are saying, everybody is taking his own risk. I just want to understand how should I interpret ECT for practical usage. On your videos it's a rare situation when you get ECTN but you are still on the slope). As I heard from one of the guides, his rules are the following. Do not ride at all if there is CT or ECTI < 10. The slope is considered to be stale enough to ride with score 20+ (but you still never forget about general safety rules). The most tricky situation is around 15, it's in not stable but you can try to ride with great level of caution, but you'd better stay home) What do you think?
+DimaFern The ECT measures initiation and propagation and trumps the CT which only measures initiation. A low ECT score means its pretty unstable, but a high score does not mean it is stable. All snowpack tests ONLY show instability. They DO NOT show stability. If it breaks clean, then the recipe is there to slide and you should not ski or ride. We get on steep terrain when there are no other signs of instability, including no propagation. The ECT is the last line of defense: we get to a slope and determined that it's good to go (no recent avalanches or other red flags), we are feeling confident in our decision. But there's one last step: an ECT. If it propagates it should turn you around because you may have missed something. If it does not, no harm done because you were going to hit it anyway.
I know this is old... but to me it depends. Anytime I get propagation I'm very hesitant. Ultimately, my decision depends a lot on what the instability is. If it's a shallow new snow instability I would be more likely to ride with a lower score. Something like the snowpack in the video, I'd probably not ride even with an ECTN. I did that recently. Got 2 ECTN results but a 2 foot hard slab was sitting on facets. In the specific locations I dug, propagation was unlikely. But if I hit a weak spot, a very potentially fatal slide would occur.
Thank you for the great video.
One thing I would find very helpful is a video about useing these tests, compression, ECT, Etc. in determining if a slope or aspect is safe. Often I can generate data, but using that data in a meaningful way can be difficult. I guess a set of hard fast rules would be helpful
Thank you for the very easy-to-understand video. There are many wonderful places in Japan's snowy mountains, and avalanche avoidance always accompanies them. I want to spend a safe skiing life with my ski friends by referring to this video.
Thanks! Excellent video. I love brushing up on everything early season and getting back into an avalanche state of mind.
Thank you!
You guys are killing it with the videos this year. Nice work.
@Rprecision: There are no hard, fast rules except "it depends". The biggest thing to remember is that a snowpit test is a tool providing you with one observation on one particular slope/aspect/location.
But like Karl said in the video, the ECT is great because it will indicate whether conditions are conducive to propagation. Which, to me, whenever I get a sizeable slab to propagate with a cleanish shear, I tend to err on the conservative side and ski mellower slopes, different aspect etc...
nice job karl
Fantastic explaination, thanks for doing that
Depth Hoar: its an avalanche's best friend and a skiers worst nightmare
Karl, I just listened to your avalanche hour podcast which brought me to this page. Thank you for all of your hard work. I was showing my girlfriend different types of pit tests today and she asked a couple of questions I hadn't thought about, but I'm now curious about. How did you determine the dimensions of the test block?
He has centimeter markings on his probes. Most probes will have this for this kind of reason and, more grimly, to allow you to establish depth of burial and therefore correct dig angle in a search situation. If you don't have that you can measure your arm (elbow to wrist or elbow to forearm) at home and use that to approximate. Standardizing is good (like getting very close to 30cmX90cm), but a reasonable approximation should have similar results.
Good vid, Karl. I note from one of your papers that this test is effective down to a depth of about 1 or maybe 1.3 meters. Have you guys been working on a method for assessing shear and propagation at greater depths? It's great to have such simple tests, but I wonder if using a standard mass (say, 1 liter water container) , dropped from particular heights onto the shovel, would make replication better and reduce the error bars that would be inherent to this method? Thanks for your work.
So would you ride on that slope? What is the rider's decision? If you get ECTP20+ is it considered to be stable enough? What is you lowest margin of ECT score that you would not ride?
+DimaFern Great question. The simplest answer is that even with a high score you should think twice about riding that slope since it propagated. You can imagine a slope where maybe the slab is thicker and requires 27 hits to get it to go, but maybe in a thinner spots near the edges of the slope you could release it with 15. In general, whenever we get propagation we are worried.
+AvalancheGuys Thank's for the answer. I understand what you are saying, everybody is taking his own risk. I just want to understand how should I interpret ECT for practical usage. On your videos it's a rare situation when you get ECTN but you are still on the slope). As I heard from one of the guides, his rules are the following. Do not ride at all if there is CT or ECTI < 10. The slope is considered to be stale enough to ride with score 20+ (but you still never forget about general safety rules). The most tricky situation is around 15, it's in not stable but you can try to ride with great level of caution, but you'd better stay home) What do you think?
+DimaFern The ECT measures initiation and propagation and trumps the CT which only measures initiation. A low ECT score means its pretty unstable, but a high score does not mean it is stable. All snowpack tests ONLY show instability. They DO NOT show stability. If it breaks clean, then the recipe is there to slide and you should not ski or ride. We get on steep terrain when there are no other signs of instability, including no propagation. The ECT is the last line of defense: we get to a slope and determined that it's good to go (no recent avalanches or other red flags), we are feeling confident in our decision. But there's one last step: an ECT. If it propagates it should turn you around because you may have missed something. If it does not, no harm done because you were going to hit it anyway.
I know this is old... but to me it depends. Anytime I get propagation I'm very hesitant. Ultimately, my decision depends a lot on what the instability is. If it's a shallow new snow instability I would be more likely to ride with a lower score. Something like the snowpack in the video, I'd probably not ride even with an ECTN. I did that recently. Got 2 ECTN results but a 2 foot hard slab was sitting on facets. In the specific locations I dug, propagation was unlikely. But if I hit a weak spot, a very potentially fatal slide would occur.
Thank you!