Elastic thickness structure of South America estimated using wavelets and satellite-derived gravity data

Spatial variations of effective elastic thickness of the lithosphere in Central America and surrounding regions

“…In any case, the high Te values recovered here for the stable platforms of the North and South American plates (see Fig. 3) are consistent with previous studies for these regions (Tassara et al , 2007;Perez-Gussinye et al 2007, 2009a; Swain 2009, 2011).…”

“…4c), a direct relationship between them is not evident. This is consistent with the scatter observed in pre vious works on other oceanic regions (e.g., Tassara et al, 2007;Kalnins and Watts, 2009). Watts (2001) uncertainties in load, infill and mantle densities, thermal perturba tions due to hot and cold spots (e.g., Tassara et al, 2007), viscoelas tic stress relaxation (Watts and Zhong, 2000), yielding in regions of large loads and high curvature (McNutt and Menard, 1982), or spatial variations in the controlling isotherms that determine Te (Kalnins and Watts, 2009).…”

“…For North America, our results are consistent with Kirby and Swain's (2009) F results, which show that subsurface loading has dominated con tinental tectonics, or at least been equal in magnitude to surface loading, in North America. Our results are also consistent with the pattern of the flexural loading ratio, fp, obtained by Tassara et al (2007) in northern South America, which suggest that below the north-eastern limit of the Amazonia craton there are strong lateral variations in density not compensated by surface topog raphy. Subsurface loading dominates along the East Pacific Rise, around the Galapagos hotspot, Cocos Ridge, Carnegie Ridge and the Cocos-Nazca spreading center (Fig.…”

“…It should also be noted that "grav itational noise" (McKenzie and Fairhead, 1997;McKenzie, 2003;Kirby and Swain, 2009) does exist in the study area, which casts doubt upon re values in some regions, especially where we have recovered very high values; we will return to this issue in the Dis cussion. Tassara et al (2007) and Kirby and Swain (2011) for northern South America using Ikol � 2.668 and Ikol � 5.336 wavelets (Supp. Fig.…”

Comment on “The West Andean Thrust, the San Ramón Fault, and the seismic hazard for Santiago, Chile” by Rolando Armijo et al.

“…Also the "fore-bulge" wavelength far exceeds the wavelength of the supposed "foredeep," something in open contradiction with flexural mechanics [Turcotte and Schubert, 1982;Watts, 2001]. Furthermore, it is very difficult to understand why the Central Valley "foreland" basin, which should have been several kilometers deep (between 4 and 6 km according to our calculations using the Cardozo and Jordan [2001] approach, for the loads reconstructed from Armijo et al's [2010] Figure 8a and elastic thicknesses between 20 and 40 km as suggested by Tassara et al [2007]) should be sediment starved. The evolution of the Argentine foreland basins, facies patterns, sediment provenance, subsidence, the age of the sedimentary fill, and its relations with deformation and uplift has been thoroughly studied [e.g., Flemings and Jordan, 1990;Jordan, 1995].…”