震惊 (zhèn jīng) means 'to shock, to astonish' and describes a strong emotional reaction to something unexpected or terrible. It is more intense than 吃惊 (chī jīng) or 惊讶 (jīng yà), which are milder 'surprise'. Compared to 震撼 (zhèn hàn), which implies a deep, shaking impact, 震惊 focuses on the sudden emotional shock itself.