Two senses to watch. Literal: a geological landslide (山体滑坡, 泥石流). Figurative: a noticeable decline — 业绩滑坡 (sales slump), 成绩滑坡 (drop in grades), 道德滑坡 (moral decline). Both senses are common in news writing.
memory
Literally 'slip' (滑) + 'slope' (坡) — picture earth literally sliding down a slope. The figurative drop-in-quality sense extends naturally from the picture of something sliding downhill.
