Answer:
What is happening at the edge of the board is "seafloor is spreading".
Step-by-step explanation:
On the tectonic map, we can see that the arrows are indicating that the seabed is spreading. This is a normal situation in the face of tectonic plate movement. At the bottom of the sea, the boundary between the separating plates is marked by a meso-oceanic dorsal that exhibits active volcanism, earthquakes and rifting caused by extensional forces (pulling) that pull two plates to opposite sides. The result is expansion from the seafloor, which occurs as a tectonic plate separates from another tectonic plate and the new seafloor is created by rising mantle.