National Geographic : 1973 Jan
where sea-floor spreading opens a new ocean (page 23). Subduction of a southeast Pacific plate beneath South America (2) uplifts the Andes and breeds the quakes that rock Chile and Peru. Similar subduction under the Indo- DRAWINGBYALFREDZEBARTH,COMPILEDBYGEORGEW. BEATTY nesian island chain fueled the 1883 eruption of Krakatoa (3). Plates rubbing edge to edge caused the catastrophic San Francisco earthquake of 1906 (4). Collision between the Arabian plate and Asia regularly jolts Iran and Turkey (5).