The word 天崩地裂 is formed by juxtaposing two parallel verb-phrase constructions: 天崩, where 天 (sky) is the subject and 崩 (collapse) is the verb, and 地裂, where 地 (earth) is the subject and 裂 (split) is the verb; these are combined into a four-character compound that literally describes the sky collapsing and the earth cracking open to convey a singular catastrophic image.