Separation of crustal and mantle geoid anomalies using the truncation of spherical harmonics expansion

• Grant number: 14/08641-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2014
• End date: July 31, 2015
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Naomi Ussami
• Grantee: Guilherme Rodrigues e Silva
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 09/50493-8 - Crustal and lithospheric mantle models under the Paraná and Chaco-Paraná basins by merging satellite gravity gradiometry, terrestrial gravimetry and geomagnetic and electromagnetic soundings, AP.TEM

Abstract

In this scientific initiation research project, we aim to evaluate the possibility of performing the truncation of spherical harmonic expansion of height geoid (EGM2008) in order to isolate the components of higher degree and order of this geopotential model that are associate with effects on geoid from crustal density anomalies. Thus, we hope to develop a technique, which allows us to determine crustal effects on geoid quickly so that we can replace the forward calculation of effects on geoid owing to topography, to sediments and chiefly to undulation in the crust-mantle interface. The forward calculation generally involves the parameterization of crustal anomalous masses in rectangular or spherical prisms that can result in excessive computational times, depending on the considered area and the data resolution. The natural case to be studied in the evaluation of the proposed method is the western United States, where the EarthScope program has provided crustal models with unprecedented resolution and accuracy worldwide and whose crustal effects on geoid have been estimated by Chaves & Ussami [2013] using the forward calculation by tesseroids.