If I understood what the USGS information regarding the 6 magnitude earthquake correctly, these earthquakes occurred in a “transform fault” zone location.

Not being a geologist, I had to stop reading the Wikipedia explanation of what a transform fault is as I started getting a headache (humor intended).

However, if I correctly understood what I did read, the transform faults are usually relatively small faults that can allow two tectonic plates to move away from one another in a somewhat organized manner even though earthquakes might be involved.

So, if that explanation is correct, the earthquakes probably occurred essentially on top of one another in a relatively small section of fault zone that is something like a vertical tube. They were like a narrow sheet of paper being torn in half starting at the top, or an overcoat zipper being opened.

Again, not being a geologist, that information might not be correct.