Browsing by Autor "Paola Montenegro"

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A robust approach to terrestrial relative gravity measurements and adjustment of gravity networks
(Springer Science+Business Media, 2024) Franco S. Sobrero; Kevin Ahlgren; Michael Bevis; Demián D. Gómez; Jacob Heck; Arturo Echalar; Dana J. Caccamise; Eric Kendrick; Paola Montenegro; Ariele Batistti
Abstract Like many geophysical observations, relative gravity (RG) measurements are affected by random errors, systematic errors, and occasional blunders. When RG measurements are used to build large gravity networks in remote areas under adverse environmental or logistical conditions (such as extreme temperatures, heavy precipitation, rugged terrain, difficult or dangerous roads, and high altitudes), it is more likely for significant errors to occur and accumulate. Therefore, obtaining accurate gravity estimates at regional gravity networks largely depends on defensive data collection protocols and robust adjustment techniques. In this work, we present a measurement field protocol based on highly redundant observation patterns, and a two-step least squares adjustment scheme implemented as a MATLAB package. This software helps us identify blunders, mitigates the impact of random errors, and downweights or removes outlier observations. The methodology also guarantees that adjusted gravity values have well-constrained standard error estimates. We illustrate the capabilities of our approach through the case study of the Bolivian gravity network, where we determined the acceleration due to gravity at 2548 stations that spread over difficult and sometimes extreme environments, with a typical level of uncertainty of 0.10–0.15 mGal.
Building a large-scale surface gravity network in Colombia using highly redundant measurements
(De Gruyter Open, 2025) Franco S. Sobrero; Michael Bevis; Demián D. Gómez; Arturo Echalar; Paola Montenegro; Eric Kendrick; Ariele Batistti; Lizeth Contreras Choque; Juan Carlos Catari; Elio B. Yucra Saavedra
Abstract This article presents a large-scale surface gravity network in Colombia, developed during a 3-year collaboration between Ohio State University (OSU) and Colombia’s national mapping agency, the Instituto Geográfico Agustín Codazzi . The network spans approximately one-third of the country’s surface area and consists of 498 stations, including 22 absolute gravity (AG) constraints. We applied the OSU field protocol and adjustment technique, extending it to address the challenge of traffic-induced noise at benchmarks located near major roads. Our methodology employed measurements with an unusually high degree of redundancy, with 87% of the gravity lines surveyed using a minimum of four relative gravimeters. Additionally, we utilized both automatic (Scintrex CG-6) and manual (LaCoste and Romberg Model G) instruments to leverage their complementary strengths in different environments. The resulting gravity values were determined with a typical uncertainty (1 sigma) of ± 0.03 mGal. The leave-one-out cross-validation tests using the AG stations demonstrated the robustness of our solution, with all residuals statistically indistinguishable from zero. Our findings show that the combination of enhanced observational redundancy and the use of multiple gravimeter types effectively mitigates measurement challenges under suboptimal conditions, with only a modest increase in field time.
Data Resource Profile: EULAT Eradicate GBC: the European-Latin American Research Consortium towards Eradication of Preventable Gallbladder Cancer
(Oxford University Press, 2025) Dominique Scherer; Carol Barahona Ponce; Claudio Mengoa; Paola Montenegro; H. Losada; Ana Lineth García; Armando Rojas; Erik Morales; Allan Vera Kortmann; Loreto Spencer
International collaborative research to improve gallbladder cancer prevention
(Nature Portfolio, 2025) Dominique Scherer; Rajiv Kumar; Justo Lorenzo Bermejo; on behalf of EULAT Eradicate GBC; Carol Barahona Ponce; Claudio Mengoa; Paola Montenegro; Albert Torres; Cristian Pacheco; Hector Losada