Refers to a disastrous, often violent or heartbreaking event, such as a massacre, accident, or catastrophe. Stronger and more dramatic than 悲劇 (ひげき), which can also refer to a theatrical tragedy.
惨劇 usually refers to a bloody, violent tragedy like a murder, while 惨事 covers any tragic accident or disaster including natural ones.
Etymology
Compound of 惨 (さん, 'miserable, wretched') and 劇 (げき, 'drama, play'), literally 'miserable drama'. The word likely originated as a translation of Western concepts of tragedy, but is now used for real-life catastrophic events.