Originally Posted by rb.
Actually, for those of you used to quakes on the west coast, they are not comparable when you cross the Rockies. The make-up and compression of the earth's crust is so different that the quakes lower on the Richter scale are felt much more severely out this way. What was felt here, well over 500 miles from the epicentre, was as strong as the close 4 I felt out of Seattle in 96 (on the border in BC). You can't compare how earthquakes feel and damage when you are on a different base. That said, it wasn't Haiti, but there was foundation damage a substantial distance from this quake...not like something you'd see in California. Think of it this way...if someone pounds the ground with a sledgehammer five feet from you, what do you feel it more on? Sand or solid rock? We sit on solid rock out here. It's called the Canadian Shield, and it's one very big rock.
You are absolutely right. Earthquakes of any magnitude will feel different depending on soil conditions.
Our first home in San Diego county was built on decomposing granite. One morning at 3 am we woke up because of a thundering sound. It sounded like thunder under the ground...really ominous sounding. Then the house and our bed started to roll, one wave after another. Scariest earthquake I remember.
Much of the soil in CA is sandy, which doesn't conduct the movement of the plates very well, but if you are on solid rock even a small earthquake will be felt.