Faults and Earthquakes - Earthquake Engineering for Structural Design - page 210

of the Cocos plate beneath the North American plate (CA-a). In the zone of the
Caribbean Isles (CA-b), some subduction interplates occur due to the interaction
between the Caribbean and North American plates. The intraplate earthquakes,
produced in seismic areas without very clear fault systems, dominate the Eastern
zones. The central zone is practically immune from earthquakes.
South American seismic zones (SA). Generally, this seismic area is regular,
without important changing along the fault. In the North part of South America, in
Venezuela (SA-a), some strike-slip earthquakes occur, due to interaction between
the Caribbean and the South American plate. Subduction crustal interplate and
intraplate earthquakes dominate the Western seismic area (SA-b), as the result of
subduction of the Nazca plate beneath the South American plate. The Eastern
South American zone is immune from earthquakes.
Figure 6. 30 Seismic zones in the North and South American continents
.