Why is al-arḍu a passive subject in zulzilat al-arḍu?

Supplementary Practice 25 — Comparative Rhetoric of Sūrat az-Zalzalah and Sūrat al-ʿĀdiyāt

• Because every definite noun must be a passive subject
• The verb is passive and the earth undergoes the shaking
• Because idhā makes every following noun a subject
• Because zilzālahā turns it into a genitive complement