New Island Off Pakistan Coast

According to the news, the recent earthquake in Pakistan has created a new island.

Seismologists suspect the island is a temporary formation resulting from a “mud volcano,” a jet of mud, sand and water that gushed to the surface as the temblor churned and pressurized that slurry under the ocean floor.

We are told this is a temporary phenomena, but are there circumstances that cause it to become permanent?
On the other hand, there are phenomena that cause solid ground to disappear and not return…

Have a great day.