Yeah - "believe." Too semantic, or not semantic enough? How about, "Do you think they have any connection with an impending earthquake?" Better?

As for the Northridge dust clouds, I stood in Newhall and watched them form. The humidity was very low the first couple of days after the quake. It was interesting because the waves from the aftershocks traveled from the south. You could see the dust clouds rising and, moments later, we would feel the aftershock. So, this is how we knew it was coming.

The altitude of the dust clouds was nominal, however.

Tony