NUVEL-1A

NUVEL-1A
Name	NUVEL-1A
Type	Plate motion model
Developers	Peter Molnar; Kenneth G. DeMets; Tim H. Dixon
Year	1990s
Region	Global plate motions
Data	Geodetic, geologic, seismic
Predecessor	NUVEL-1
Successor	Various GPS-based models

NUVEL-1A NUVEL-1A is a global plate motion model developed in the 1990s that estimated angular velocities for major tectonic plates using marine magnetic anomalies, earthquake slip vectors, and geodetic constraints. It refined the earlier NUVEL-1 model to better represent plate circuits and relative motions involving the Pacific, Nazca, Cocos, North American, South American, African, Eurasian, Indian, Antarctic, Caribbean, Scotia, Arabian, Philippine, and Australian plates. The model influenced subsequent work in plate tectonics, seismology, geodesy, and mantle dynamics.

Overview

NUVEL-1A was produced by researchers associated with institutions such as the National Science Foundation, Scripps Institution of Oceanography, University of Wisconsin–Madison, and Lamont–Doherty Earth Observatory. It built on foundational concepts from the Vine–Matthews–Morley hypothesis, the mapping of mid-ocean ridges such as the Mid-Atlantic Ridge and East Pacific Rise, and the consensus reached at gatherings like the International Union of Geodesy and Geophysics meetings. NUVEL-1A provided angular velocity vectors consistent with transform fault azimuths and fracture zone orientations observed near plates like the Cocos Plate, Nazca Plate, Juan de Fuca Plate, and Philippine Sea Plate, and it was cited in studies addressing subduction zones including the Cascadia subduction zone, Peru–Chile trench, and Japan Trench.

Methodology

The methodology combined marine magnetic anomaly chronologies established by researchers linked to the Ocean Drilling Program, paleomagnetic syntheses influenced by work at Geological Survey of Canada, and earthquake focal mechanism compilations from agencies like the United States Geological Survey and the International Seismological Centre. NUVEL-1A used rigid plate rotation theory formalized in the tradition of W. Jason Morgan and empirical constraints similar to those applied in models from teams at Caltech, Massachusetts Institute of Technology, and University of Cambridge. The inversion employed least-squares fitting across plate circuit closures that included arcs such as the Aleutian Islands, the Caribbean Plate boundaries, and the Mediterranean Sea region.

Data and Models

Input data encompassed marine magnetic anomaly identifications tied to magnetic polarity timescales such as the Geomagnetic Polarity Time Scale, fracture zone traces mapped by expeditions funded by the National Oceanic and Atmospheric Administration, and tectonic reconstructions referencing classic works by John Tuzo Wilson and Vine and Matthews. NUVEL-1A integrated seafloor spreading rates inferred from anomalies named for chrons like Chrons C1–C5, transform fault geometries near the Galápagos Islands, and seismicity catalogs including events from the 1976 Tangshan earthquake era through the 1990s. The model used spherical trigonometry methods grounded in formulations by Alfred Wegener's intellectual descendants and computational approaches similar to those applied in plate reconstructions at Paleomagnetism Laboratory groups.

Results and Implications

Results provided angular velocity poles and relative plate speeds that revised estimates for plates including the Pacific Plate, Eurasian Plate, North American Plate, South American Plate, African Plate, and Indian Plate. NUVEL-1A's outputs affected interpretations of mantle convection models explored at institutions like the Geophysical Fluid Dynamics Laboratory and fed into seismic hazard assessments used by agencies such as the Federal Emergency Management Agency and national mapping agencies. The model contributed to improved reconstructions of continental breakups involving past configurations like Pangaea and informed studies of hotspot tracks associated with volcanic chains such as the Hawaiian–Emperor seamount chain and the Iceland plume.

Limitations and Uncertainties

NUVEL-1A assumed plates behave as rigid bodies, an approximation discussed in critiques originating from researchers at Stanford University, University of Oxford, and ETH Zurich. The model predated dense continuous observations from the Global Positioning System networks established by organizations including International GNSS Service and thus could not capture short-term intraplate deformation documented later in studies of regions like the Himalayas, the East African Rift, and the Anatolian Fault. Uncertainties arose from magnetic anomaly identification ambiguities, errors in marine geophysical surveys by vessels like the historic Glomar Challenger, and incompletely sampled plate boundaries such as parts of the Antarctic Plate margin and the complex collisional zones adjoining the Arabian Plate and Eurasian Plate.

Historical Context and Development

NUVEL-1A emerged from a lineage including early seafloor spreading syntheses by researchers at Scripps Institution of Oceanography and the Lamont Geological Observatory in the 1960s and 1970s, and was contemporaneous with evolutions in geodetic practice at centers like Jet Propulsion Laboratory and the National Aeronautics and Space Administration. The update from NUVEL-1 to NUVEL-1A reflected improved mapping of transform faults, fracture zones, and magnetic anomalies enabled by multinational programs such as the International Ocean Discovery Program and collaborations with geological surveys including the United States Geological Survey and British Geological Survey. Subsequent models leveraging continuous GPS, satellite altimetry from missions like TOPEX/Poseidon, and gravity field data from GRACE extended and refined the framework first codified in NUVEL-1A.

Category:Plate tectonics