Chris Zweck

Remarkably extensive glaciation and fast deglaciation and climate change in Turkey near the Pleistocene-Holocene boundary

Moraines in the Taurus Mountains of south-central Turkey, dated to latest Pleistocene or earliest Holocene, show that glaciers were extraordinarily large, typical of the Last Glacial Maximum (21 ka), and that rates of glacier retreat and temperature rise exceeded those of the past century. Surface exposure ages of 7 moraines in a valley at altitudes between 1100 m and 3100 m above sea level range from 10.2 ± 0.2 ka to 8.6 ± 0.3 ka, computed using our own production rates and spatiotemporal scaling factors. Hitherto unresolved differences in cosmogenic 36 Cl production-rate estimates can make these ages signifi cantly older, and therefore the analysis presented here focuses on the rate of change and not on the absolute chronology. During deglaciation, the equilibrium line altitude ascended 1430 m and the air temperature rose by 9 °C. Deglaciation occurred in two phases. During the second, faster phase, which lasted 500 yr, the glacier length decreased at an average rate of 1700 m/100 yr, implying a warming rate of 1.44 °C/100 yr, indicating a rapid climate shift marking the onset of the Holocene in Turkey.

The 1964 great Alaska earthquake: present day and cumulative postseismic deformation in the western Kenai Peninsula

Abstract Global Positioning System (GPS), triangulation and leveling data are used to derive models for the present day (last ∼5 years) and the 30-year average postseismic deformation on the Kenai Peninsula, Alaska following the 1964 Alaska earthquake. The two datasets are inverted using a three-dimensional elastic dislocation model to estimate the magnitude and spatial distribution of slip on the North America–Pacific plate interface, allowing us to examine the time dependence of the processes controlling postseismic deformation. We determine that the 30-year average postseismic slip rate beneath the western Kenai Peninsula was about twice as large as the present day slip rate. The observations suggest a time-decaying process, but are not consistent with a single exponentially decaying relaxation process initiated immediately after the 1964 earthquake. We conclude that the postseismic deformation observed on the western Kenai Peninsula cannot be explained in terms of any single time-decaying process. Either multiple processes acting on different timescales or significant spatial propagation of the postseismic deformation, or both, must occur. In the latter case, postseismic deformation would not begin everywhere at the same time and the rate of spatial propagation would affect the timescale inferred for the postseismic processes.

The potential of the COSMOS network to be a source of new soil moisture information for SMOS and SMAP

The COSMOS network will eventually consist of several hundred sensors throughout the United States that report kilometer-scale soil water content via measurement of the intensity of neutrons immediately above Earths surface. We show that COSMOS sensors must be corrected for the effects of growing vegetation. Once this phenomenon is completely understood the COSMOS network could be a useful source of information for the validation of both soil moisture and vegetation products obtained from current and future microwave remote sensing satellites.

ACE: Age Calculation Engine-A Design Environment for Cosmogenic Dating Techniques

ACE (age calculation engine; previously called iCronus) is a design environment for analyzing data used in cosmogenic dating methods. It is supported by a software architecture designed with flexibility, scalability, security and safety in mind. These properties have allowed us to create an environment that directly supports the tasks that geoscientists perform as they work on developing new algorithms for cosmogenic dating, such as running calibrations, defining new experiments, and evaluating the impacts of scaling factors on the calculated ages of samples. Our goal is to provide geoscientists using cosmogenic dating methods with a flexible and powerful software infrastructure upon which to base their future research efforts. In this paper, we describe the design of the ACE system and compare it to existing cosmogenic dating software. We also discuss how our system has been evaluated and our plans for future work.

End-to-End support for dating paleolandforms

Experts in scientific fields routinely operate under less-than-ideal conditions. We present a deployed data analysis system for cosmogenic isotope dating, a domain that is fraught with difficult automation issues. First, experts must work with a huge array of possible parameters. Our system ACE handles this issue by pushing the bounds of software flexibility. Furthermore, isotope dating experts reason about groups of samples using a large number of vague and contradictory heuristics. Calvin, an argumentation system, addresses this issue. Our intelligent data analysis tool is in daily use by isotope dating experts.