4th small quake in northwestern Arizona this week

We've had a small spate of small quakes in the northwest corner of the state this week with the fourth one occurring at 7:53 a.m, yesterday.    The earthquakes are still widely scattered and do not appear to be related.  The latest one was 17 miles south-southeast of St. George, Utah. [Right, the latest quake epicenter shown in blue.   The week's previous quakes are in yellow. Credit, USGS]