Here's why:

* Seismic means related to earthquakes.

* Aseismic means not related to earthquakes.

While all faults are capable of producing earthquakes, some remain relatively inactive. This could be due to several factors, including:

* Low stress levels: The rocks on either side of the fault may not be under enough pressure to cause movement.

* High friction: The rocks on either side of the fault may be very rough, making it difficult for them to slip past each other.

* Slow, creeping movement: The fault may be moving very slowly, without producing noticeable earthquakes.

It's important to remember that even aseismic faults can sometimes produce significant earthquakes, especially if the stress levels build up over time.