Monitoring Crustal Deformation in Eastern Maine Using GPS

Abstract

As a part of an ongoing study of crustal dynamics in New England, the University of Maine undertook a study of crustal subsidence in Eastern Maine. Previous studies have indicated a subsidence rates of the coastal region with respect to stable inland monuments of up to 9 mm/yr. These studies were based on the analysis of repeated leveling of first‐ and second‐order level lines in the region. The last epoch of releveling was completed in 1966. In order to continue monitoring this subsidence, a new network of stations traversing the area of suspected subsidence, including stations in stable areas, was established. Considering the time and cost of releveling, along with the precision requirements of the survey, GPS provides the only practical means for monitoring the subsidence network in an ongoing and timely manner. A total of 20 new and existing stations were combined to form the new subsidence network. The network design considerations in terms of the required precision of the resulting observations are discussed. Initial observation results and comparisons to prior subsidence rate estimates are provided.