pertaining to the structure or movement of the earth's crust
<adj.pert> tectonic plates tectonic valleys
of or pertaining to construction or architecture
<adj.pert>
Tectonic \Tec*ton"ic\, a. [L. tectonicus, Gr. ?, fr. ?, ?, a carpenter, builder.] 1. Of or pertaining to building or construction; architectural.
2. (Biol.) Structural. [Webster 1913 Suppl.]
3. (Geol. & Phys. Geog.) Of, pert. to, or designating, the rock structures and external forms resulting from the deformation of the earth's crust; as, tectonic arches or valleys; tectonic plates. [Webster 1913 Suppl. +PJC]
The Japanese archipelago sits along a fault line between massive tectonic plates which slowly grind against each other.