Circular Features

Cochise College
Geology Home Page  
Geology Exploration Using Google Earth            
Roger Weller, geology instructor
copyrighted by Roger Weller  3/22/18
Base for diagrams is Google Earth

Earthquakes in USA Conterminous 48 States and Adjacent Areas
Oct. 2012 to Jan. 2016

  All earthquake epicenters are included, except for California where only 3.0 and larger earthquakes
are represented.  If all California earthquakes were to be included, there would only be a black
patch covering most of California. 

     A goal for geologists has always been to develop an understanding of where we expect earthquakes
to occur.  The primary approach has been to look for patterns in the collection of earthquake epicenters. 
Since there is an obvious relationship the San Andreas fault and earthquakes, an arrangement of
earthquake epicenters in straight linear pattern suggests they indicate  hidden fault.  This has long been
a successful process in identifying faults hidden below the surface.

     However, if you remove all of the earthquake epicenters that lie in straight lines, you are still left with
a large number of seemingly unrelated earthquake epicenters.  This study examines those earthquake
epicenters whose locations suggest large circular patterns.  This report will concentrate on just these
circular patterns.

Overview of new earthquake patterns observed from Oct. 2012 to Jan. 2016
(note:  after January 2016 most of the circular patterns along the west coast vanished and earthquakes
tended to move towards the East.  On the East coast earthquake activity greatly slowed down.)

Earthquake data was tabulated in three month segments, starting in October 2012 through January
2016.  A statistical process was developed in order to generate the straight blue line segments seen in the
above map; 4 or more epicenters in a straight line received a blue line.  Also to this map were blue lines
that were assigned to circular patterns.

Earthquakes have been removed to show the resulting patterns.

The long linear strips were by connecting 4 or more earthquakes that occurred in a straight
line.  On the other hand, the circular features were determined by numbers of earthquakes
falling upon a circular path and these circular patterns were also assigned blue lines.

This report is broken up into 3 sections.


Analysis of 38 circular earthquake patterns

Validation of the reality of these circular patterns
Summary Discussion