Moho map of South America from receiver functions and surface waves

Abstract

[1] We estimate crustal structure and thickness of South America north of roughly 40°S. To this end, we analyzed receiver functions from 20 relatively new temporary broadband seismic stations deployed across eastern Brazil. In the analysis we include teleseismic and some regional events, particularly for stations that recorded few suitable earthquakes. We first estimate crustal thickness and average Poisson's ratio using two different stacking methods. We then combine the new crustal constraints with results from previous receiver function studies. To interpolate the crustal thickness between the station locations, we jointly invert these Moho point constraints, Rayleigh wave group velocities, and regional S and Rayleigh waveforms for a continuous map of Moho depth. The new tomographic Moho map suggests that Moho depth and Moho relief vary slightly with age within the Precambrian crust. Whether or not a positive correlation between crustal thickness and geologic age is derived from the pre-interpolation point constraints depends strongly on the selected subset of receiver functions. This implies that using only pre-interpolation point constraints (receiver functions) inadequately samples the spatial variation in geologic age. The new Moho map also reveals an anomalously deep Moho beneath the oldest core of the Amazonian Craton.Citation: Lloyd, S., S. van der Lee, G. S. França, M. Assumpção, and M. Feng (2010), Moho map of South America from receiver functions and surface waves,

Estimates of stress drop and crustal tectonic stress from the 27 February 2010 Maule, Chile, earthquake: Implications for fault strength

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A New Seismic Data Set on the Depth of the Moho in the Alps

“…The ZK technique has been applied worldwide in multiple studies (e.g., FRANÇA and ASSUMPÇ AO 2004;GEISSLER et al 2008;PIANA AGOSTINETTI and AMATO 2009;LLOYD et al 2010;GALLACHER and BASTOW 2012) and is a well-established method to estimate depths and V p /V s ratios for simple crustal structures. Complex tectonic environments prove to be a challenge for ZK technique, since the RF time series are composed of a multitude of converted phases due to the occurrence of several seismic discontinuities in the crust (e.g., CHAMPION et al 2006).…”

Three-Dimensional Shear Wave Velocity Structure of the Northeastern Brazilian Lithosphere

“…In conclusion, CRUST2.0 global model does not show any relevant variation in Moho depth from one geological province to another and this result does not reflect the complex geological reality of the region ( [46]). Three-dimensional Moho image of the northeastern Brazil based on the methodology proposed in this study, and some isolated crustal thicknesses obtained via seismic (square-28 km [41]; triangle-40 km [40]; red numbers [42]; black numbers [43]) and gravimetric methods (white isolines [44]). Numbers close to the isolines are the corresponding crustal thicknesses.…”