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You may also be looking for the novel Off Armageddon Reef.

Map of Armageddon Reef

Armageddon Reef was a vast reef in the southern hemisphere of Safehold, south-west of Charis Island and south of the Sea of Justice.

It was created when Eric Langhorne had the Alexandria Enclave destroyed by a kinetic bombardment from orbit to prevent Dr. Pei Shan-wei's rebellion against his doctrine from spreading. (OAR)

What was left after the attack was nothing but a barren wasteland, which in addition was officially considered "cursed" by the Church of God Awaiting, thus preventing humans from ever settling in the area again. (AMF)