The Ramu - Markham Fault Zone is the active plate boundary between the South Bismarck Plate and terranes within the New Guinea Highlands Deforming Zone .
The Ramu - Markham Fault Zone follows the northern edge of the Markham Valley .
The Ramu - Markham Fault Zone , which follows the northern edge of the Markham Valley , is the active plate boundary between the South Bismarck Plate and terranes within the New Guinea Highlands Deforming Zone .