"A 7.2-magnitude earthquake off the southern coast of Newfoundland in 1929 caused a large underwater landslide, creating a large wave that rushed ashore and killed 28 people on the island, ten Brink said. The waves were up to 26 feet high until some reached narrow inlets, where they grew to 43 feet (13 m), he said."
> An offshore earthquake of magnitude 4.5 or above could cause submarine avalanches and create dangerous tsunamis with waves higher than 26 feet
Turbidity currents occur on the regular without earthquakes and rarely result in substantial waves. They have been observed to happen due to earthquakes, but this is a rare event. The Grand Banks quake is the only known earthquake to have done this, and as you pointed out it was an earthquake with a much larger magnitude.
In the grand scheme of things, turbidity events don't significantly impact the overall risk of tsunamis. The tsunami risk overwhelmingly comes from the earthquakes themselves, not the turbidity events they may trigger.
https://en.wikipedia.org/wiki/2011_Virginia_earthquake
The US east coast faces a tsunami risk from undersea avalanches on the edge of the continental shelf:
https://www.livescience.com/24813-east-coast-tsunamis.html
"An offshore earthquake of magnitude 4.5 or above could cause submarine avalanches and create dangerous tsunamis with waves higher than 26 feet (8 meters), [...] Underwater canyons and bays could focus these waves and make them even bigger."