Magnitude scale a poor measure of localized shaking

After an earthquake like the one that struck Cook Inlet on Sunday morning, everyone wants to know how big it was. Scientists use a magnitude scale to describe the size of an earthquake. But getting to that number is a complicated process. And it has some major limitations.
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A USGS earthquake map shows lots of seismic activity around Anchor Point, including the 7.1M shaker felt from Fairbanks to Juneau (big yellow dot). Image: screen grab from USGS
Numbers like 6.4… 7.3&helli