An earthquake occurs during a dinner party in Los Angeles. When the shaking subsides, Joe attempts to impress the other guests by proclaiming, “It felt like a 5.5 to me.’’ Even assuming that Joe can...

An earthquake occurs during a dinner party in Los Angeles. When the shaking

subsides, Joe attempts to impress the other guests by proclaiming, “It felt like a

5.5 to me.’’ Even assuming that Joe can reliably estimate the local ground accelerations, what vital piece of information does he lack that limits the accuracy of

his magnitude estimate?