What are the striations or ridges in the eastern Pacific Ocean?
They are fracture zones.

I've annotated your image with the names of these very long, tectonically important features. They even have names, such as the Mendocino Fracture Zone:



I also labelled some survey tracks (rather subtle, very straight, very regular in width), which are data artifacts — these are the things you noticed radiating from the vicinity of Los Angeles.

There are yet other types of linear feature on the sea floor:


Transform faults are strike-slip faults connecting segments of spreading centres in the oceanic crust.
The spreading centres themselves.
Roughly linear archipelagos like Hawaii.
The long, curved trenches at convergent plate margins.


Images from Google Maps. Note: I edited this answer substantially after the OP clarified the question... and I learned about the difference between transform faults and fracture zones.