The motion of the Pacific plate relative to Pacific hotspots produces age-progressive chains of volcanoes. New methods of analysis of volcano locations and age dates using a small number of adjustable parameters (10 per chain) are presented. Simple fits to age progressions along Pacific hotspot chains indicate $1\sigma$ age uncertainties of $\approx\pm$1.0 to $\pm$3.0 Ma. Motion between the Hawaii and Louisville hotspots differs insignificantly from zero with rates of 2$\pm$4 mm/a (=$\pm$2$\sigma$) for 0–48 Ma and 26$\pm$34 mm/a (=$\pm$2$\sigma$) for 48–80 Ma. Relative to a mean Pacific hotspot reference frame, motions of the Hawaii, Louisville, and Rurutu hotspots are also insignificant. Therefore plumes underlying these Pacific hotspots may be more stable in a convecting mantle than previously inferred. We find no significant difference in age between the Eocene bends of the Pacific hotspot chains. The best-fitting assumed-coeval age for the bends is 47.4$\pm$1.0 Ma (=$\pm$2$\sigma$), coincident with the initiation of the doubling of the spreading rate of the Pacific plate relative to the Farallon and Vancouver plates. The initiation of the Eocene slowdown of India preceded the bends and was completed after the bends. Any causal relation of this slowdown to the Hawaiian-Emperor bend remains obscure. On the other hand, initiation of subduction of the Pacific plate in the west and southwest Pacific Ocean Basin likely preceded the formation of the bends, consistent with subduction initiation changing the torque on the Pacific plate such that it started moving in a more westward direction thus creating the Hawaiian-Emperor Bend.

Magnetic trackline data are of central importance in estimating relative plate motions, have allowed a detailed apparent polar wander path to be determined for the Pacific Plate from skewness analysis, and provide important constraints for many other geophysical investigations. Interpreting trackline data typically requires processing, which often involves dividing tracks into quasi-linear segments. Here we present a method for automating this processing step by adapting the Ramer-Douglas-Peucker (RDP) algorithm, originally developed for polygonal approximation and cartographic generalization, for use on trackline data on a sphere and demonstrate its ability to segment data into quasi-linear (i.e., great circle-like) sections quickly based on two intuitive parameters. The new procedure is largely automated and requires minimal effort. As a test and proof of concept, we apply this method to estimate an angular velocity for motion between the Pacific and Rivera plates since 0.781 Ma using data from the NCEI geophysical trackline database. Our modified RDP algorithm identified 400+ track segments that intersected the Rivera Rise, of which more than 50 provided useful Pacific-Rivera spreading rates, which is roughly twice the 26 rates used to estimate Pacific-Rivera motion in the MORVEL set of geologically current plate relative angular . We compare the resulting angular velocity to previous estimates of Pacific-Rivera angular velocity and explore implications for Pacific-North America and Pacific-Cocos relative motion and Rivera absolute motion.

The paleolatitude distribution of paleoclimate proxies and contintential landmass is an important constraint for modeling and understanding paleoclimate. True polar wander (TPW), which can produce large, potentially rapid changes in paleolatitude, is a necessary component in paleolatitude reconstructions. Prior workers, e.g., van Hinsbergen et al. (2015), have created paleolatitude frameworks from global continental apparent polar wander paths (APWPs) drawn from running means of continental paleomagnetic studies (e.g., Torsvik et al. 2012). These are limited by the precision of the running mean, poor age resolution amplified by use of a running mean, and the uncertainties and the unknowns of ancient plate motion circuits. In particular, the Pacific Plate is linked to the global plate circuit through Antarctica. Early paleomagnetic tests of this circuit (Suarez & Molnar, 1980; Gordon & Cox 1980; Acton & Gordon 1994) indicated inconsistency of the circuit with paleomagnetic data such that the reconstructed Pacific plate did not move as far north as indicated by its indigenous paleomagnetic data. Some later work has asserted, however, that updated paleomagnetic data and plate reconstructions no longer indicate the inconsistency found before (Doubrovine & Tarduno 2008). Important progress has also been made in estimating the motion between East and West Antarctica from seafloor data (e.g. Granot & Dyment 2018). We revisit these questions here. We test the predictions of the global paleolatitude framework at points across the Pacific Plate using a well-constrained observed APWP constructed from indigenous Pacific plate data from skewness analysis of marine magnetic anomalies (Schouten & Cande 1976; Cox & Gordon 1980) and locations of paleo-equatorial sediments (Moore et al. 2004; Woodworth & Gordon 2018), which uniquely determine Pacific Plate paleolatitude independent of plate circuits. The misfit between the observed and predicted paleolatitude varies with longitude across the plate and is as large as ~10±3°, with the largest misfit occurring between 40 and 60 Ma. Implications of this discrepancy will be discussed and an improved paleolatitude framework for the Pacific plate will be presented.