Sections of active fault lines that haven't experienced a significant earthquake for a long time, even though adjacent sections have, are called

Sections of active fault lines that haven't experienced a significant earthquake for a long time, even though adjacent sections have, are called Seismic gap.

Sections of active fault lines that haven't experienced a significant earthquake for a long time, even though adjacent sections have, are called

A. seismic gaps.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

answer; the region experienced a surplus of food;