EARTHQUAKES OCCUR AT PLATE BOUNDARIES IN AGREEMENT WITH THE TOPOGRAPHIC FEATURES

(MID-OCEAN RIDGES, DEEP-SEA TRENCHES, TRANSFORM FAULTS)

THEY SHOW THAT THE FEATURES ARE ACTIVE BOUNDARIES WHERE MOTION OCCURS TODAY

THEY CAN BE USED TO IDENTIFY PLATE BOUNDARIES WHERE THEY ARE NOT OBVIOUS:

- NORTH AMERICA - EUROPE BOUNDARY: A MIDOCEAN RIDGE UNDER THE ICE SHEET IN THE ARCTIC OCEAN

- NORTH AMERICA - SOUTH AMERICA BOUNDARY IN THE ATLANTIC:

WHERE THERE IS NO MAJOR TOPOGRAPHIC FEATURE (BECAUSE THE PLATE MOTION IS VERY SLOW)

THEY SHOW THE DIRECTIONS OF PLATE MOTIONS

(Press & Siever)