Choice of solid vs. engineered is a technical one with a personal "bank account" attached to the decision. Engineered hardwood floors are great in areas that find it hard to handle solid: concrete slabs in Texas and Florida for instance. Engineered can be used in a basement whereas solid cannot.

Frequent earth quakes will shake any floor. Especially a floor that is glued/nailed in place. A 'floating' engineered hardwood might take the earth movement in a better way...but that's the only reason I can think of.

The humidity control in the home is also part of the equation. If you want a wide plank product in a very dry/very humid environment (where you have NO control of humidity) then the engineered product is the "more stable" of the two options. A wide plank engineered floor can still have problems...it just has fewer of them.

Do you have a concrete slab or are your subfloors plywood? Let's start with the basics.

thank you for the response, have concrete slab

We are on a slab also..and we went with an unfinished engineered glue down random lenth 5inch wide plank. It was then sanded, stained and sealed like a real nail down floor. I think the random lenth is important for it to look like a real wood floor. Engineered is more stable and we didnt have to worry about the added height that a nail down wood floor would have been.

With a concrete slab Engineered flooring becomes almost mandatory. All of our CA client use Engineered flooring not because of earth quakes but because of climate/humidity issues.