Andean Volcanic Belt• Formed in S. American crustal plate by

subduction of the oceanic Nazca Plate.• Four main volcanic zones.• Varied tectonic settings include rift

systems, extensional zones, seamount chains

• Differences in volcanic zones as well as between neighboring volcanos.

Reference: Wikipedia, image reference by Chiton magnificuss

Iquique Chile: April 1, 2014• M8.2 megathrust earthquake• West coast of northern Chile• Triggered 2 meter high tsunamiForeshock sequence began March 16, 2014.Aftershock sequence M4.7-7.8Last fault rupture: M8.8 in 1877

Oceanic Nazca Plate subducts beneath continental S. American plate.

Plate convergence rates

Plate divergent rates

Northern Volcanic Zone• Subduction of Nazca under S. America.• 74 volcanoes formed by subduction.• Extends from Columbia to Ecuador.

Nevado del Ruiz is covered by glaciers.Image by Edgar, CC-A-SA 2.0

Southern Volcanic Zone• Flat slab subduction of Juan Fernandez

Ridge marks northern boundary.• Volcanic gap produced by subduction type.

Nevados de Chillán is most active in this region. Image by pabloendemico, CC-A 2.0

Austral Volcanic Zone• Formed by subduction of Antarctic Plate

under S. American Plate.• Glaciated stratovolcanoes, subglacial

volcanoes under S. Patagonian Ice Field.

Reference: Wikipedia Andean Volcanic Belt

Central Volcanic Zone• Subduction of Nazca under S. America.• 44 major and 18 minor volcanic centers.• Contains 6 active silicic volcanic systems

Andean Volcanic Belt

Earthquakes in Red Lines Region• Large earthquakes ,shallow depths 0-70 km• Due to crustal and interplate deformation• Crustal earthquakes from mountain

building in S. American plate• Interplate earthquakes due to slipping of

Nazca plate

Earthquakes in Yellow Line Region• Large intermediate depth , 70-300 km• Due to internal deformation of Nazca Plate• Beneath Chile, Peru, Bolivia, Ecuador

Earthquakes in Blue Line Regions• Deep focus at 500-650 km• None at 300-500 km• Due to continued Nazca plate deformation• First area runs beneath Peru-Brazil border• Second area from central Bolivia to central

Argentina.• Generally not of large magnitudes.• Exception 1994 Bolivia M8.2 at 631 km

depth• One of the largest deep-focus earthquakes• Felt throughout S. and N. America.

Reference: U.S. Geological Survey event page

Earthquake Regions