Reno, Nevada has been experiencing earthquakes that have been steadily increasing in intensity, counter to the "normal" pattern of strong quake followed by smaller aftershocks, and scientists are trying to figure out why.

Up until April 15, sizable quakes that could be felt were occurring about once every third day.

Then, the rate increased, with about three, 2.0 or larger incidents occurring daily.

On April 24, when the first 4.2 quake was registered, "all of a sudden we were seeing 20 (of the magnitude) 2s and larger per day," said state geologist Jon Price.

"This is an exceptionally vigorous sequence of earthquakes," Price said.

During the past week alone, more than 500 occurrences have been recorded.

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