I lived about 300 km from the epicenter for many years. Large parts of that region are nothing but jungle and rivers, with little villages spread around. The natives build their houses/huts mostly using tree trunks tied together with vines, which are surprisingly resistant to strong earthquakes because the structure is so flexible.

Yurimaguas and Tarapoto do have a sizeable population, but still, from what I heard so far the damage is nothing compared to the 2007 M8 quake that destroyed 85% of Pisco and killed many hundred people.