Models for extracting vertical crustal movements from leveling data

Various adjustment strategies are being used in North America to obtain vertical crustal movements from repeated leveling. The more successful models utilize polynomials or multiquadric analysis to describe elevation change with a velocity surface. Other features permit determination of nonlinear motions, motions associated with earthquakes or episodes, and vertical motions of blocks where boundaries are prespecified. The preferred models for estimating crustal motions permit the use of detached segments of releveling to govern the shape of a velocity surface and allow for input from nonleveling sources such as tide gages and paired lake gages. Some models for extracting vertical crustal movements from releveling data are also excellent for adjusting leveling networks, and permit mixing old and new data in areas exhibiting vertical motion. The new adjustment techniques are more general than older static models and will undoubtedly be used routinely in the future as the constitution of level networks becomes mainly relevelings

The Earth as an Altar: Understanding Humanity\u27s Place and Duty in Creation through Neo-Calvinism

Eoghan Holdahl, a Dordt University junior and member of the Kuyper Honors Program majoring in Agriculture and Community Development, submitted this essay to the Lambertus Verburg Prize for Excellence in Kuyperian Scholarship competition, 2023

Theoretical and Experimental Investigations into the Evolution of Populations and their Behavior

This dissertation examines game theory and evolutionary dynamics, exploring strategic decision-making, social norm emergence, and inter-group conflicts. Chapter 2 focuses on stepping stones, recurrent classes that facilitate equilibrium transitions. An experiment tests their effectiveness in promoting the transition to a Pareto efficient equilibrium. Results show groups with stepping stones consistently achieve the high-payoff equilibrium, contrasting occasional failures in groups without them. Information about other players' payoffs is crucial, with complete information outperforming incomplete information. However, the effect diminishes with stepping stones, emphasizing their low-cost transitions. Players' decision-making behavior and factors influencing deviations are also examined. Chapter 3 explores the role of incomplete sampling in determining convergence to conventions in adaptive play. The chapter demonstrates that even minimal incomplete sampling is sufficient for convergence to occur in the 2x2 coordination game. The analysis also reveals that incomplete sampling criteria are often unnecessary, expanding the boundaries of adaptive play theory. The implications of incomplete sampling on the perturbed adaptive process are examined, identifying a robust resistance function that persists under different degrees of sampling. In Chapter 4, the effects of signaling in inter-group conflicts are investigated. The competitive advantage of costly signaling within groups is examined, and a model is developed to explore the dynamics of inter-group conflicts. The findings suggest that shorter periods of isolation and more efficient weapons favor the rise of signaling norms in societies. Overall, this dissertation provides valuable insights into game theory, evolutionary dynamics, and their implications for strategic decision-making, social norms, and inter-group conflicts. The findings contribute to interdisciplinary fields such as economics, sociology, and political science, offering a foundation for further research in these areas. This dissertation includes both previously published co-authored material and unpublished co-authored material

Satellite applications to marine geodesy

Potential use of satellites for enhancing positioning capabilities and for marine geodetic contro

Growing in Global Perspectives: A Book Conversation of Reading the Bible Around the World

... God uses the oppressed to represent Jesus, the Savior, in [the Good Neighbor] story. Posting about the book Reading the Bible Around the World from In All Things - an online journal for critical reflection on faith, culture, art, and every ordinary-yet-graced square inch of God’s creation. https://inallthings.org/growing-in-global-perspectives-a-book-conversation-of-reading-the-bible-around-the-world

Growing in Global Perspectives: A Review of Reading the Bible Around the World

Effects of colonization, refuge seeking, and persecution affect how communities interpret meaning in Scripture. Posting about ­­­­­­­­the book Reading the Bible Around the World from In All Things - an online journal for critical reflection on faith, culture, art, and every ordinary-yet-graced square inch of God’s creation. https://inallthings.org/growing-in-global-perspectives-a-review-of-reading-the-bible-around-the-world

On the use of repeat leveling for the determination of vertical land motion: artifacts, aliasing and extrapolation errors

Leveling remains the most precise technique for measuring changes in heights. However, for the purposes of determining vertical land motion (VLM), a time series of repeat leveling measurements is susceptible to artifacts and aliasing that may arise due to systematic errors, seasonal surface fluctuations, motions occurring during a survey, and any inconsistencies in the observation conditions among epochs. Using measurements from 10 repeat leveling surveys conducted twice yearly along a profile spanning ~40 km across the Perth Basin, Western Australia, we describe the observation, processing, and analysis methods required to mitigate these potential error sources. We also demonstrate how these issues may lead to misinterpretation of the VLM derived from repeat leveling and may contribute to discrepancies between geologically inferred rates of ground motion or those derived from other geodetic measurement techniques. Finally, we employ historical (~40‐year‐old) leveling data in order to highlight the errors that can arise when attempting to extrapolate VLM derived from a geodetic time series, particularly in cases where the long‐term motion may be nonlinear

The apparent British sea slope is caused by systematic errors in the levelling-based vertical datum

The spirit-levelling–based British vertical datum (Ordnance Datum Newlyn) implies a south–north apparent slope in mean sea level of up to 53 mm deg–1 latitude, due to the datum falling on heading northwards. Although this apparent slope has been investigated since the 1960s, explanations of its origin have remained inconclusive. It has also been suggested that, rather than a slope, the British vertical datum includes a step of about 240 mm affecting all sites north of about 53°N. In either case, the British vertical datum may be of limited use for any study requiring accurate heights or changes in heights, such as testing geoid models, groundwater and hydrocarbon extraction, the calibration and validation of satellite-based digital terrain models, and the unification of vertical datums internationally. Within the last decade, however, based on an apparent reduction in the slope to only −12 mm deg–1 latitude with respect to recent geoid models, it has been claimed that the British vertical datum does provide a physically meaningful surface for use in scientific applications.In this paper, we reinvestigate the presence of apparent south–north sea slopes around Britain and reported slopes in the vertical datum, using the EGM2008 global gravitational model, together with mean sea level and GPS data from British tide gauges, GPS ellipsoidal heights of 178 fundamental benchmarks across mainland Britain, and vertical deflection observations at 192 stations. We demonstrate a south–north slope in the British vertical datum of −(20–25) mm deg–1 latitude with respect to both mean sea level (corrected for the ocean's mean dynamic topography and the inverse barometer response to atmospheric pressure loading) and the EGM2008 quasigeoid model, while EGM2008 is shown to exhibit a negligible slope of (2 ± 4) mm deg–1 with respect to mean sea level. It is clear, therefore, that the slope can only arise from systematic errors in the levelling, although we are unable to isolate their exact origin. Using an offset detection method based on a penalized likelihood maximization using the Schwarz Information Criterion, we do not detect a step in the vertical datum affecting all sites north of 53°N, but do identify regional distortions that we attribute to the inhomogeneity in both the levelling data used and the least squares adjustment procedures used to realize the datum. We conclude that the British vertical datum remains unsuitable for scientific purposes