DYNAMICS OF PLATE INTERIORS
Geodynamics Series, Vol. 1
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DYNAMICS OF PLATE INTERIORS, GEODYNAMICS SERIES, VOL. 1, PAGES 131–144, 1980


Releveling data in North America: Implications for vertical motions of plate interiors

Larry D. Brown and Robert E. Reilinger


Department of Geological Sciences, Cornell University, Ithaca, New York

Abstract

Precise leveling is the most commonly used method for detecting and mapping vertical movements of the earth's surface over periods of days to decades. Compared with currently available alternatives, leveling is more stable over large periods of time and long baselines, yet is less costly and more accurate over short to moderate distances. However, application of leveling measurements to the investigation of vertical tectonics of plate interiors has had mixed results. While studies to date have demonstrated the potential usefulness of leveling, they have also drawn attention to our inadequate understanding of both the accuracy of the measurements used to infer crustal motion as well as the tectonic processes responsible for such motion. Leveling observations of vertical movement in seismic areas, while in many cases poorly understood, are nevertheless often accepted as geologically significant because such movements are not unexpected in tectonically active areas and can be associated with likely causative mechanisms. On the other hand, similar measurements have been interpreted as indicating substantial vertical motion in 'stable* plate interiors, where tectonic activity is generally unexpected, and plausible mechanisms are difficult to identify. The latter group of observations especially has raised some fundamental questions concerning the reliability of leveling estimates of vertical movement (at least in some cases), the time behavior of any true movements, and the nature of the neotectonic forces which may be currently deforming plate interiors. Although apparent movements of the 'stable' interior are more difficult to understand, and are thus subject to correspondingly more skepticism, they are potentially the more informative regarding heretofore unsuspected or unrecognized intraplate neotectonic processes. This report attempts to briefly review and summarize the current status of research using leveling measurements as a guide to intraplate tectonics in North America, identify those related topics where further investigation is most needed, and offer suggestions regarding which approaches are most likely to effectively address the critical issues. We believe that the North American results are representative of similar measurements in other countries, and therefore that the inferences drawn from them are universally applicable.

Citation: Brown, L., and R. E. Reilinger, (1980), Releveling data in North America: Implications for vertical motions of plate interiors, in Dynamics of Plate Interiors, Geodyn. Ser., vol. 1, edited by A. W. Bally et al., pp. 131-144, AGU, Washington, D. C.