Common compounds: 倒塌 (dǎotā, to collapse), 坍塌 (tāntā, to cave in), 塌方 (tāfāng, landslide/cave-in). Also used figuratively: 天塌了 (the sky has fallen, i.e., a catastrophe).
Earth radical on the left — when something 塌s, it is earth or earthwork that gives way: a wall caving in, a roof falling, ground sinking. The radical anchors 塌 in the soil/structure family alongside 坍 (collapse), 堵 (block), 坑 (pit), 城 (city wall).
Top of the right side — 日 sits above 羽, together forming the phonetic 㯱 (tà). Here 日 is just the upper graphic of that compound; it does not contribute meaning on its own. Walking the nested IDS exposes both pieces so each can be looked up.
Bottom of the right side. Together with 日 above it forms the phonetic compound that gave 塌 its tā reading (via Old Chinese tap-final). Visually two compressed feather shapes. Pure phonetic role; 'feathers' contributes nothing semantic to 'collapse.'
