Kapr, Emily: Establishing a Local Geoid Model in Costa Rica

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Title:  Establishing a Local Geoid Model in Costa Rica

Name: Emily Kapr

Major: Physics

School affiliation: School of Arts and Sciences

Programs: Aresty – RA Program

Other contributors: Isabelle Stern, Oscar Lucke, Vadim Levin

Abstract: This project seeks to use Global Navigation Satellite System and gravity data collected in Costa Rica to contribute to local geoid model development. A geoid model is an equipotential surface, which coincides with that represented by the mean, undisturbed sea level. It is important to find the local geoid model for Costa Rica because it helps scientists advise contractors where infrastructure can be located when developing civil engineering projects and aiding tectonic and volcanic hazard prevention. To construct a geoid model for Costa Rica, we conducted fieldwork at sixteen locations in Costa Rica, including Cerro de la Muerte and Volcan Irazú. The data is processed, uploaded to QGIS, and compared to global geoid models of varying degrees and orders. Global geoid models with higher degrees and order are expected to closely correspond to geoid height values gathered at leveled benchmarks known as geometric geoid separations. We find this is true for the benchmarks on Cerro de la Muerte, but not for the benchmarks on Volcan Irazú. We expect this discrepancy is a result of the spatial distribution of historical data. The gravimeter is also a critical part of modeling the geoid because it will locate gravity anomalies below Earth’s surface. Gravity anomalies will give insight to isostasy, or subsurface mass distribution, in the Cordillera Talamanca region. We successfully processed and set up tables of this data to perform further comparisons. Gravity and geoid height data will be further analyzed and used to propose modifications to the existing local geoid model.