+- Earthwaves Earth Sciences Forum (http://www.earthwaves.org/forum)
+-- Forum: Earthwaves (http://www.earthwaves.org/forum/forumdisplay.php?fid=16)
+--- Forum: Earth Sciences (http://www.earthwaves.org/forum/forumdisplay.php?fid=11)
+--- Thread: snowquakes on my roof (/showthread.php?tid=61)
snowquakes on my roof - Island Chris - 02-18-2014
There is a nice analogue experiment going on the roof of our house on the island. We have solar shingles, which have low friction coefficient, and we have regular shingles below the solar shingles, which have high friction coefficient. We have a 15 cm of heavy wet snow. It starts to creep down the solar shingles, adding shear stress to the shear stress from gravity (as resolved onto 27 degree dip of roof). Then, we have sudden, violent avalanches, which last about 1 to 2 s, and I think could injure someone if they were on our deck. This is essentially a snowquake.
A bit more than half of the solar shingles avalanched 2 days ago.
The other side has slid a half meter at the top, on the solar, but is stuck on the regular shingles at the bottom. The shortening in between has created a fold and thrust belt in the snow.
The odd thing is that our last two snow quakes were within two minutes of the same time, about a week apart: 2:01 PM local time and the 1:59 PM local time. We know this because we bet on it.
Chris
The snowquake of the rest of our roof just occurred, at 4:23 PM local time. A bit less violent than the last one, but kind of impressive anyway.
Chris
RE: snowquakes on my roof - Skywise - 02-18-2014
I remember when I was a kid and living in Utah for a couple years, there was such heavy snow fall that authorities were recommending people to shovel it off. Buildings and houses were caving in under the weight. Our house had something like 2-1/2 feet on it. I forget what we calculated the weight to be, but it was a few tons. ISTR a house across the street developing a sag in it's roof.
As a kid at the time, it was all fun and games to me, especially since that was the first time I lived in snow.
Brian