There's water in the rocks. When it rains water gets trapped between rocks and layers of rock.
Then a storm comes in, more water, water is flowing filling cracks, pooling wherever it can, lightning strikes, the water trapped in and around some of the rocks very quickly heats up, turns to steam, and kaboom, you now have moving rock.
Presumably lightning strike erosion is a lot of energy over a short time compared to wind or water erosion which is much less energy but over much longer periods?
There are some high resolution nightside lighting storms from orbiting camera compilations on youtube that might impress just how much power zaps down in strikes.
I've been camping on a mountainside when a storm came over at night and rocky outcrops on the ridge above us were struck repeatedly by lightning.
In the morning, clear blue skies, and we climbed up to have a look. Was sadly not very dramatic, we were expecting chunks of rock blown off, but you could see that the sudden heat had created fresh fissures, and around what we thought was the ground zero of a strike, the surface of the rock had become friable for a few centimetres.
But water/ice is always going to be a dominant feature in rock wasting, those lightning cracks just give it easier ingress.
Then a storm comes in, more water, water is flowing filling cracks, pooling wherever it can, lightning strikes, the water trapped in and around some of the rocks very quickly heats up, turns to steam, and kaboom, you now have moving rock.
Presumably lightning strike erosion is a lot of energy over a short time compared to wind or water erosion which is much less energy but over much longer periods?