Department of Geosciences

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Aging dams, political instability, poor human decisions and climate change: recipe for human disaster
Shirzaei, Manoochehr; Vahedifard, Farshid; Sadhasivam, Nitheshnirmal; Ohenhen, Leonard; Dasho, Oluwaseyi; Tiwari, Ashutosh; Werth, Susanna; Azhar, Mohammed; Zhao, Yunxia; Nicholls, Robert J.; AghaKouchak, Amir (Springer Nature, 2025-01-16)
In Derna, Libya, a record-breaking storm and subsequent dam failures on September 10, 2023, caused over 11,000 deaths. Analyzing satellite data from 2016–2023, we found 1.8 mm/yr of differential settlement in dams contributed to their failure, and flooding damaged ~8570 buildings. We argue that the interplay of aging infrastructure, political instability, climate change, and human decisions drove this disaster, stressing the need for a holistic ‘healthcare’ management approach to prevent future catastrophes.
Boulder dislodgement during coastal storms and tsunamis: Insights from a new ensemble model
Weiss, Robert; Irish, Jennifer L.; Goodman Tchernov, Beverly (American Geophysical Union, 2022-03-01)
Boulders are excellent candidate deposits to study coastal inundation events by storms and tsunamis due to their significant preservation potential. However, it is difficult to infer how and what forcing dislodged the boulder. We present a new model that enables ensemble and Monte-Carlo-type simulations to study the sensitivity of boulder, the fluid flow, and environmental parameters. Our examples show that boulder transport is complex and nonlinear, and to acknowledge the uncertainties of the boulder's preexisting transport conditions, a range of velocities and environmental parameters should be used to quantify the flow that caused boulder dislodgement.
Editorial for Special Issue “Nanomineralogy”
Ju, Yiwen; Wan, Quan; Hochella, Michael F. Jr. (MDPI, 2020-06-05)
Nanoscience and nanotechnology study the properties of materials within the range 0 [...]
Extinctions, Morphological Gaps, Major Transitions, Stem Groups, and the Origin of Major Clades, with a Focus on Early Animals
Xiao, Shuhai (Wiley, 2022-12-30)
Systematic extinctions can leave major morphological gaps between living crown-group clades. Such morphological gaps would be perceived, from a neontological point of view, as major evolutionary transitions. In order to fill these morphological gaps and to map the evolutionary steps toward major evolutionary transitions, we need to integrate extinct stem-group taxa in phylogenetic studies. However, the recognition of stem group has not been widely adopted in the study of early animal fossils, despite that all fossils are stem groups at one level or another. Part of the difficulty is that stem groups may not have all features that collectively diagnose the respective crown group, and they can have unique (autapomorphic) features, making them tantalizingly similar to and frustratingly different from the crown group (e.g., stem-group eukaryotes can be prokaryotic and stem-group animals can be protistan). The need to embrace stem groups and to implement the PhyloCode, in order to achieve phylogenetic clarity and to offer key paleontological insights into the origin and early animal evolution, is illustrated in debates on several controversial Ediacaran and Cambrian fossils.
Geodynamic investigation of a Cretaceous superplume in the Pacific ocean
Xue, Jing; King, Scott D. (Elsevier, 2016-08-01)
The similarity in both age and geochemistry of the Ontong-Java, Hikurangi, and Manihiki plateaus suggests that they formed as a single superplateau from a unique mantle source. We investigate the necessity of a thermal superplume to form the Great Ontong-Java plateau at about 120 Ma using 3D spherical models of convection with imposed plate reconstruction models. The numerical simulations show that the giant plateau which formed as a result of melting due to the interaction of a plume head and the lithosphere would have been divided into smaller plateaus by spreading ridges, and end up at the present locations of Ontong-Java, Manihiki, and Hikurangi plateaus as well as a fragment in the western Caribbean. By comparing temperature and melt fraction between models with and without an initial thermal superplume, we propose that a Cretaceous superplume in Pacific at 120 Ma is required to form large igneous plateaus.
Hotspot swells revisited
King, Scott D.; Adam, Claudia (Elsevier, 2014-10-01)
The first attempts to quantify the width and height of hotspot swells were made more than 30. years ago. Since that time, topography, ocean-floor age, and sediment thickness datasets have improved considerably. Swell heights and widths have been used to estimate the heat flow from the core-mantle boundary, constrain numerical models of plumes, and as an indicator of the origin of hotspots. In this paper, we repeat the analysis of swell geometry and buoyancy flux for 54. hotspots, including the 37 considered by Sleep (1990) and the 49 considered by Courtillot et al. (2003), using the latest and most accurate data. We are able to calculate swell geometry for a number of hotspots that Sleep was only able to estimate by comparison with other swells. We find that in spite of the increased resolution in global bathymetry models there is significant uncertainty in our calculation of buoyancy fluxes due to differences in our measurement of the swells' width and height, the integration method (volume integration or cross-sectional area), and the variations of the plate velocities between HS2-Nuvel1a (Gripp and Gordon, 1990) and HS3-Nuvel1a (Gripp and Gordon, 2002). We also note that the buoyancy flux for Pacific hotspots is in general larger than for Eurasian, North American, African and Antarctic hotspots. Considering that buoyancy flux is linearly related to plate velocity, we speculate that either the calculation of buoyancy flux using plate velocity over-estimates the actual vertical flow of material from the deep mantle or that convection in the Pacific hemisphere is more vigorous than the Atlantic hemisphere.
Machine learning and marsquakes: a tool to predict atmospheric-seismic noise for the NASA InSight mission
Stott, A. E.; Garcia, R. F.; Chedozeau, A.; Spiga, A.; Murdoch, N.; Pinot, B.; Mimoun, D.; Charalambous, C.; Horleston, A.; King, Scott D.; Kawamura, T.; Dahmen, N.; Barkaoui, S.; Lognonne, P.; Banerdt, W. B. (Oxford University Press, 2023-01-04)
The SEIS (seismic experiment for the interior structure of Mars) experiment on the NASA InSight mission has catalogued hundreds of marsquakes so far. However, the detectability of these events is controlled by the weather which generates noise on the seismometer. This affects the catalogue on both diurnal and seasonal scales. We propose to use machine learning methods to fit the wind, pressure and temperature data to the seismic energy recorded in the 0.4–1 and 2.2–2.6 Hz bandwidths to examine low- (LF) and high-frequency (HF) seismic event categories respectively. We implement Gaussian process regression and neural network models for this task. This approach provides the relationship between the atmospheric state and seismic energy. The obtained seismic energy estimate is used to calculate signal-to-noise ratios (SNR) of marsquakes for multiple bandwidths. We can then demonstrate the presence of LF energy above the noise level during several events predominantly categorized as HF, suggesting a continuum in event spectra distribution across the marsquake types. We introduce an algorithm to detect marsquakes based on the subtraction of the predicted noise from the observed data. This algorithm finds 39 previously undetected marsquakes, with another 40 possible candidates. Furthermore, an analysis of the detection algorithm’s variable threshold provides an empirical estimate of marsquake detectivity. This suggests that events producing the largest signal on the seismometer would be seen almost all the time, the median size signal event 45–50 per cent of the time and smallest signal events 5−20 per cent of the time.
Mantle temperature and density anomalies: The influence of thermodynamic formulation, melt, and anelasticity
Adam, C.; King, Scott D.; Caddick, Mark J. (Elsevier, 2021-10)
Deriving a quantitative geodynamical interpretation from tomography models is a difficult task. It is also a timely task, particularly given the many high-resolution tomography models published in recent years. It is important to assess mantle structure in terms of density and temperature anomalies. Here, we provide a new estimation of the conversion factors between seismic velocity anomalies and density anomalies, Rρ/v, and between seismic velocity anomalies and temperature anomalies, RT/v. These conversion factors are found by considering the constraints provided by thermodynamics, the influence of melt, and anelasticity. To determine the elastic component, we performed thermodynamic simulations by considering several compositions representative of normal or plume-enriched mantle. We also explore the effects of the presence of melt on seismic velocity and consider a radial attenuation profile to account for anelasticity. We provide an envelope of acceptable models, by combining the range of possible solutions combining the elastic, anelastic, and melt relationships used in deriving the conversion factors. Several of the frequently used velocity-density scaling relationships are encompassed in this envelope. We assess the validity of our result by calculating temperature anomalies from the tomographic models using our scaling relationships—these anomalies lie within the range constrained by melting temperatures registered in volcanic rocks (±300 K). Further, we show that the geoid model computed through our velocity-density scaling from the S40RTS tomography provides a good fit to the observed geoid.
Morphology: Too hip for two sacral vertebrae
Stocker, Michelle R. (eLife, 2019-12-19)
A complex pelvic morphology has been discovered in the fossils of one of the largest crocodylians.
Optimizing Satellite Mission Requirements to Measure Total Suspended Solids in Rivers
Stroud, Molly K.; Allen, George H.; Simard, Marc; Jensen, Daniel; Gorr, Ben; Selva, Daniel (IEEE, 2023-11-29)
Human modification of the landscape affects total suspended solid (TSS) concentrations in water. The quantitative extent of these changes remains poorly understood, partly because of the challenges associated with observing TSS dynamics in inland waters over large scales. While many current missions and sensors provide usable data to estimate inland water quality (e.g. Landsat series, VIIRS, and Sentinel-2), future missions present the opportunity to increase transferability and accuracy of TSS estimation. Here, we degrade assumed ideal spectral data to evaluate the optimal data quality for TSS retrieval using an optical sensor configuration. We also perform wavelet analysis and a river size distribution analysis to study temporal and spatial data quantity requirements, respectively. We find that while the highest resolution data always gives the best retrieval accuracy, some factors are more essential in TSS estimation than others and can simplify mission design. Specifically, fine hyperspectral resolution is key in improving retrieval accuracy and a finer spatial resolution allows exponentially more river surface area to be observed. A revisit period of approximately five days or less best captures TSS pulse events, such as floods. Understanding the optimal mission specifications for observing inland water quality, especially TSS, will assist in developing and proposing future optical satellite missions.
A problematic animal fossil from the early Cambrian Hetang Formation, South China - A reply
Tang, Qing; Hu, Jie; Xie, Guwei; Yuan, Xunlai; Wan, Bin; Zhou, Chuanming; Dong, Xu; Cao, Guohua; Lieberman, Bruce S.; Leys, Sally P.; Xiao, Shuhai (Cambridge University Press, 2019-11-01)
We recently reported Cambrowania ovata Tang and Xiao in Tang et al., 2019, from the early Cambrian Hetang Formation in South China and interpreted it as a problematic animal fossil, possibly related to either sponges or bivalved arthropods (Tang et al., 2019). Slater and Budd (2019) contested our taxonomic identification and phylogenetic interpretation; instead, they claimed that Cambrowania ovata is a large acritarch referable to morphotaxon Leiosphaeridia Eisenack, 1958, and thus is not an animal. Here we refute their criticisms, clarify the differences between Cambrowania and Leiosphaeridia and other acritarchs, and reiterate why an animal affinity for Cambrowania cannot be ruled out.
Review of ESA SYMP 7: A Dynamic Perspective on Ecosystem Restoration–Establishing Temporal Connectivity at the Intersection Between Paleoecology and Restoration Ecology
Reid, Rachel E. B.; McGuire, Jenny L.; Svenning, Jens‐Christian; Wingard, G. Lynn; Moreno‐Mateos, David (Wiley)
The Sedimentary Geochemistry and Paleoenvironments Project
Farrell, Una C.; Samawi, Rifaat; Anjanappa, Savitha; Klykov, Roman; Adeboye, Oyeleye O.; Agic, Heda; Ahm, Anne-Sofie C.; Boag, Thomas H.; Bowyer, Fred; Brocks, Jochen J.; Brunoir, Tessa N.; Canfield, Donald E.; Chen, Xiaoyan; Cheng, Meng; Clarkson, Matthew O.; Cole, Devon B.; Cordie, David R.; Crockford, Peter W.; Cui, Huan; Dahl, Tais W.; Mouro, Lucas D.; Dewing, Keith; Dornbos, Stephen Q.; Drabon, Nadja; Dumoulin, Julie A.; Emmings, Joseph F.; Endriga, Cecilia R.; Fraser, Tiffani A.; Gaines, Robert R.; Gaschnig, Richard M.; Gibson, Timothy M.; Gilleaudeau, Geoffrey J.; Gill, Benjamin C.; Goldberg, Karin; Guilbaud, Romain; Halverson, Galen P.; Hammarlund, Emma U.; Hantsoo, Kalev G.; Henderson, Miles A.; Hodgskiss, Malcolm SW W.; Horner, Tristan J.; Husson, Jon M.; Johnson, Benjamin; Kabanov, Pavel; Brenhin Keller, C.; Kimmig, Julien; Kipp, Michael A.; Knoll, Andrew H.; Kreitsmann, Timmu; Kunzmann, Marcus; Kurzweil, Florian; LeRoy, Matthew A.; Li, Chao; Lipp, Alex G.; Loydell, David K.; Lu, Xinze; Macdonald, Francis A.; Magnall, Joseph M.; Mand, Kaarel; Mehra, Akshay; Melchin, Michael J.; Miller, Austin J.; Mills, N. Tanner; Mwinde, Chiza N.; O'Connell, Brennan; Och, Lawrence M.; Ossa Ossa, Frantz; Pages, Anais; Paiste, Kart; Partin, Camille A.; Peters, Shanan E.; Petrov, Peter; Playter, Tiffany L.; Plaza-Torres, Stephanie; Porter, Susannah M.; Poulton, Simon W.; Pruss, Sara B.; Richoz, Sylvain; Ritzer, Samantha R.; Rooney, Alan D.; Sahoo, Swapan K.; Schoepfer, Shane D.; Sclafani, Judith A.; Shen, Yanan; Shorttle, Oliver; Slotznick, Sarah P.; Smith, Emily F.; Spinks, Sam; Stockey, Richard G.; Strauss, Justin V.; Stueken, Eva E.; Tecklenburg, Sabrina; Thomson, Danielle; Tosca, Nicholas J.; Uhlein, Gabriel J.; Vizcaino, Maoli N.; Wang, Huajian; White, Tristan; Wilby, Philip R.; Woltz, Christina R.; Wood, Rachel A.; Xiang, Lei; Yurchenko, Inessa A.; Zhang, Tianran; Planavsky, Noah J.; Lau, Kimberly V.; Johnston, David T.; Sperling, Erik A. (Wiley, 2021-07-05)
Seismic Sources in the Aleutian Cradle of Tsunamis
Witter, Rob; Briggs, Rich; Dura, Tina; Engelhart, Simon; Nelson, Alan (2022-10-01)
Vertical Displacements and Sea-Level Changes in Eastern North America Driven by Glacial Isostatic Adjustment: an Ensemble Modeling Approach
Williams, Karen; Stamps, D. Sarah; Melini, Daniele; Spada, Giorgio (Wiley, 2024-10)
Glacial isostatic adjustment (GIA) describes the response of the solid Earth, oceans, and gravitational field to the spatio-temporal evolution of ice sheets during a glacial cycle. Present-day vertical displacements and sea-level changes vary throughout eastern North America in response to the melting of the Laurentide Ice Sheet following the Last Glacial Maximum. We use the open-source software SELEN4.0 (a SealEveL EquatioN solver) to investigate the influence of GIA on vertical land motions and sea-level changes in eastern North America. Further, we evaluate the uncertainties associated with the lithospheric thickness and viscosity structure using an ensemble modeling approach (129,956 total simulations). We identify the best-fitting rheological profiles by comparing modeled vertical displacements to vertical velocity rates derived from Global Positioning System (GPS). We find a general pattern of subsidence (causing accelerated relative sea-level rise) in the eastern United States region and uplift (causing relative sea-level fall) in the eastern Canada region consistent with previous studies for two tested ice sheet models (ICE-6G(VM5a) and ICE-7G(VM7)). Overall, we find lower rates of modeled vertical displacement using ICE-6G(VM5a) compared with ICE-7G(VM7), which produces lower residuals when compared with the GPS-derived vertical velocity rates. Our ensemble analysis identifies adjustments to the nominal VM5a and VM7 viscosity models that improve fits to the GPS-imaged vertical velocity rates throughout eastern North America and on the North American Atlantic Coast. The differences in our best-fitting models for inland versus coastal regions highlight the importance of exploring lateral viscosity variations for GIA modeling throughout North America and elsewhere.
The worm turned, and the ocean followed
Lyons, Timothy W.; Gill, Benjamin C. (National Academy of Sciences, 2009-05-19)

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