À falta de melhor interpretação poderia traduzir por "zona afectada", "local atingido"...

Bom trabalho!

Eu diria assim

"Perturbado" appears to be a common expression in Portuguese in this context ... one example:



Bem preservado, constitui um óptimo exemplar de um monumento megalítico, transmitindo ao visitante a imagem de uma sepultura pré-histórica pontualmente perturbada pelos agentes naturais e humanos.

From:
http://72.14.207.104/search?q=cache:2AqFzDu9_moJ:www.cm-moim...

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Note added at 6 hrs (2006-02-22 18:02:48 GMT)
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http://www.iambiente.pt/IPAMB_DPP/docs/RNT1322.pdf

This includes a phrase concerning "zona não perturbada" (Unfortunately my Adobe Reader is not working properly for me to quote it.) The point is not the object (zona, monumento, camada, etc.), but the activity...I prefer "perturbado" because it fits the connotation of the original "disturbed" better, indicating a negative consequence. "Alterado" and "afectado" are neutral (the author could have said modified or affected) and can be positive or negative in their consequences. That's my way of looking at it, anyway. The asker has the full context and the ultimate choice.