I am wondering about the Richter Scale. The biggest
earthquake I have ever felt was the one in Northridge, Ca. I live in
Orange County (at least 60 miles from the epicenter), and I am curious as
to what the magnitude of the earthquake was 60 miles away? Thank you in
advance, this has really been on my mind.
The Richter scale is a measure of how much total energy an earthquake puts
into shaking things around. It is a common logarithmic scale, which means
that each unit on the Richter scale represents a tenfold increase in energy
released. It's not a measure of how much the ground shakes at any
particular place. So, the magnitude of the Northridge earthquake was around
7. That's the whole earthquake, not what it felt like at any particular
The extent of shaking at any particular place during an earthquake depends
on the distance from the epicenter, the amount of energy released in the
quake, the tendency of the ground to shake, and the tendency of the
intervening material to transmit the earthquake energy.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012