Carnegie Ridge

Wide-angle seismic reflection and refraction data acquired over the central and eastern part of the ridge give crustal thicknesses of 13 km and 19 km respectively for crust that has estimated ages of about 11 Ma and 20 Ma.

[4] The formation of the Carnegie Ridge and other aseismic ridges in this part of the Pacific started at about 20 Ma when the Galapagos hotspot formed, following the break-up of the Farallon Plate and the formation of the separate Cocos and Nazca Plates.

At about 19.5 Ma, the Galápagos spreading center (GSC) moved so that most of the hotspot magmatism affected the Nazca Plate, forming the combined Carnegie and Malpelo Ridges.

The GSC moved north again at about 5 Ma, leaving the hotspot entirely within the Nazca Plate, which is the current situation.

[1] The presence of a flat section is not supported by a more recent study of earthquake hypocenters, which found a constant dip of about 25°–35° down to 200 km.

Outline of aseismic ridges and plate boundaries off northwestern South America, suggested continuation of Carnegie Ridge beneath Ecuador from Gutcher et al. 1999, [ 1 ] other models suggest that this area is much smaller