About

Maureen Long is the Bruce D. Alexander '65 Professor and Chair of the Department of Earth & Planetary Sciences at Yale University. She is an observational seismologist specializing in mantle dynamics, with particular focus on subduction zone processes, the structure and evolution of continental lithosphere, and the dynamics of the deep mantle. Her research involves using seismic observations and geodynamic models to understand subduction geodynamics, including volatile cycling, melt generation and transport, slab morphology, rheology, and evolution. She investigates seismic anisotropy and flow in the deep mantle, including the transition zone, uppermost lower mantle, and the core-mantle boundary region. Additionally, her work encompasses the structure, evolution, and deformation of continental lithosphere in regions of present-day tectonic activity such as Cascadia and western South America, as well as areas affected by past subduction and continental breakup like eastern North America. Her research includes a substantial field component, with recent or ongoing seismometer deployments across various regions including the Pacific Northwest, Peru, the Appalachian Mountains, Newfoundland, and New England. Since joining Yale in 2009, she has taught courses on seismology, natural disasters, and forensic geosciences. She has served as Chair of the EPS department, Director of Graduate Studies, and chair of the departmental DEI committee, demonstrating her commitment to diversity and inclusion. She is also dedicated to public education and outreach, having run the Field Experiences for Science Teachers (FEST) program at Yale, which provides field experiences for Connecticut high school science teachers.

Research topics

• Geophysics
• Geology
• Petrology
• Seismology
• Physics
• Computer Science
• Optics
• Mathematics
• Mathematical optimization
• Telecommunications

Selected publications

• Crustal Structure of Laurentia and Peri‐Gondwanan Terranes Beneath Ireland and Britain and Comparison With Eastern North America

  Journal of Geophysical Research Solid Earth · 2026-02-01

  articleOpen access

  Abstract The Appalachian‐Caledonian orogen was built during the Paleozoic by accretion of peri‐Gondwanan terranes onto Laurentia, culminating in the formation of Pangea. During the Mesozoic, Pangea broke apart, displacing one section of the belt to eastern North America and another to northwestern Europe. These areas share aspects of their tectonic history but have been shaped differently by later Paleozoic orogenesis and Mesozoic rifting; therefore, comparisons between these regions offer an opportunity to understand which processes have been responsible for shaping their present‐day crustal structure. This study compares the crustal structure across the Laurentian and peri‐Gondwanan sutures in these regions and explores how it has been shaped by their tectonic histories. We use receiver functions with harmonic decomposition to analyze the geometry of Laurentia, Ganderian and Avalonian crust beneath Ireland and Britain and compare them with New England, northeastern USA. The Laurentian crustal thickness beneath Ireland and Britain ranges from ∼26 to 32 km, whereas that of the peri‐Gondwanan terranes varies from ∼32 to 38 km. Our analysis also provides insight into dipping interfaces and anisotropy near the Moho, which vary considerably across the study area. In contrast to our findings in Ireland and Britain, beneath New England Laurentian crust is significantly thicker (∼44 km) than accreted terrane crust (∼32 km). We hypothesize that Mesozoic rifting led to significant thinning of Laurentian crust beneath Ireland and Britain, and that regionally specific orogenic processes during the middle and late Paleozoic controlled the evolution of accreted terrane crust differently in these areas.

  PublisherOA PDFDOI

• Evidence for Caribbean Plate Subduction Beneath the Isthmus of Panama and Implications for Subduction Initiation and the Closure of the Central American Isthmus During the Miocene

  Geochemistry Geophysics Geosystems · 2025-11-01 · 1 citations

  articleOpen access

  Abstract The evolution of the Isthmus of Panama during the Miocene resulted in climatic shifts leading to global cooling, reorganization of ocean currents, and regional mass extinctions. The causes of this change in ocean circulation between ∼15 and 5 Ma have been debated, with various tectonic scenarios being proposed as explanations for this event. However, few geophysical imaging investigations have been carried out beneath Panama to probe the tectonic structure of this region. Here we investigate the crust and upper mantle of the Isthmus of Panama, directly beneath the Panama Canal, using seismic receiver function analysis. We focus on back‐azimuthal harmonic regression to isolate directionally dependent signals. We report evidence for clearly defined southernly dipping anisotropic layers at depths between ∼38 and 49 km, coincident with relocated seismicity beneath the Panama landmass. Our tectonic interpretation is informed by a synthetic modeling exercise incorporating a Bayesian inversion framework to investigate the harmonic regression terms. We interpret our results as evidence for Caribbean Plate subduction beneath the Isthmus of Panama. Considering our results, the depths of relocated seismicity, and present‐day plate motion, we estimate that Caribbean Plate subduction initiated ∼14–10 Ma, broadly coincident with changes in deep ocean circulation through what is today the Panama landmass. We propose that incipient subduction caused progressive uplift of the overriding plate, leading to the cessation of deepwater flow ∼7.5 Ma and of shallow water flow ∼5 Ma, and culminating in the formation of the isthmus of Panama and the Great American Biotic Interchange by ∼2.7 Ma.

  PublisherDOI

• Mantle Transition Zone‐Penetrating Upwellings Beneath the Eastern North American Margin and Beyond

  Journal of Geophysical Research Solid Earth · 2025-04-01 · 3 citations

  articleOpen access

  Abstract Low‐velocity anomalies in the upper mantle beneath eastern North America, including the Northern Appalachian Anomaly (NAA), the Central Appalachian Anomaly (CAA), and the weaker Southern Coastal Anomaly (SCA), have been characterized by many continent‐scale and regional seismic studies. Different models have been proposed to explain their existence beneath the passive margin of eastern North America, variously invoking the past passage of hot spot tracks, modern upwelling due to edge‐driven convection, or other processes. Depending on the nature and origin of these anomalies, they may influence, and/or be influenced by, the mantle transition zone (MTZ) structure beneath them. Previous receiver function studies have identified an overall thinner MTZ beneath the eastern margin of the US than beneath the continental interior. In this study, we resolve the MTZ geometry beneath these low‐velocity anomalies in unprecedented detail using the scattered wavefield migration technique. We find substantially thinned MTZ beneath the NAA and the CAA, and a moderately thinned MTZ beneath the SCA. In all cases, the thinning is achieved via a minor depression of the 410‐km discontinuity and a major uplift of the 660‐km discontinuity, which suggests the presence of a series of MTZ‐penetrating deep upwellings beneath eastern North America. The upwellings beneath eastern North America and a similar style upwelling beneath Bermuda may initiate from ponded thermally buoyant materials below the MTZ fed by hot return flows from the descending Farallon slab in the deep mantle.

  PublisherOA PDFDOI

• Shear wave splitting characteristics of vertically aligned partial melt discs in a subduction zone back-arc setting

  Physics of The Earth and Planetary Interiors · 2025-09-16

  articleSenior author
  PublisherDOI

• Lithospheric deformation and Mantle flow in the asthenosphere-lithosphere system of the flat slab subduction beneath the Peruvian Andes with probabilistic finite-frequency SKS splitting intensity tomography

  2025-03-15

  preprintOpen accessSenior author

  Flat or near-horizontal subduction of oceanic lithosphere is suggested to occur for ~10% of Earth’s subduction zones. While it is therefore not the dominating geometry, it has been suggested to have significant impact on tectonic processes both currently and in the geologic past. As an example, the ongoing subduction of the aseismic Nazca Ridge beneath South America has been associated with the onset of flat subduction and the termination of arc volcanism in Peru.In this study, we investigate the impact of flat-slab subduction on the mantle flow and deformation in the larger asthenosphere-lithosphere system beneath the northern portion of the South American subduction zone. Strain in the asthenospheric and lithospheric mantle causes an alignment of intrinsically anisotropic mantle minerals, particularly olivine. The resulting bulk anisotropy can be measured as splitting of core-mantle converted phases, parameterized by the delay time and the fast splitting direction. While shear phases are commonly investigated for average splitting parameters, the tomographic inversion of shear wave splitting data for upper mantle anisotropy has been a longstanding challenge for classical analysis techniques. Recent developments involve the calculation of finite-frequency sensitivity kernels for SKS splitting intensity observations, which allow us to take advantage of overlapping sensitivity kernels at adjacent stations to localize anisotropic structure at depth.Here we apply probabilistic, finite-frequency SKS splitting intensity tomography to all available datasets across the Andes in Peru and Bolivia to improve our understanding of mantle flow and deformation in the lithosphere in the complex flat slab subduction scenario. While the data sets are mostly comprised of dense lines of seismic stations, the broad lateral distribution of the different networks allows us to combine the data set in a 3D tomographic inversion for upper mantle anisotropy.

  PublisherDOI

• Deformation along the Nashoba-Avalon terrane boundary in Eastern Massachusetts

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• TESTING FOR CHANNEL FLOW ALONG THE NASHOBA-AVALON TERRANE BOUNDARY IN EASTERN MASSACHUSETTS

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• Advances in Mapping Lowermost Mantle Convective Flow With Seismic Anisotropy Observations

  Reviews of Geophysics · 2024-05-17 · 19 citations

  articleOpen access

  Abstract Convective flow in the deep mantle controls Earth's dynamic evolution, influences plate tectonics, and has shaped Earth's current surface features. Present and past convection‐induced deformation manifests itself in seismic anisotropy, which is particularly strong in the mantle's uppermost and lowermost portions. While the general patterns of seismic anisotropy have been mapped for the upper mantle, anisotropy in the lowermost mantle (called D′′) is at an earlier stage of exploration. Here we review recent progress in methods to measure and interpret D′′ anisotropy. Our understanding of the limitations of existing methods and the development of new measurement strategies have been aided enormously by the availability of high‐performance computing resources. We give an overview of how measurements of seismic anisotropy can help constrain the mineralogy and fabric of the deep mantle. Specifically, new and creative strategies that combine multiple types of observations provide much tighter constraints on the geometry of anisotropy than have previously been possible. We also discuss how deep mantle seismic anisotropy provides insights into lowermost mantle dynamics. We summarize what we have learned so far from measurements of D′′ anisotropy, how inferences of lowermost mantle flow from measurements of seismic anisotropy relate to geodynamic models of mantle flow, and what challenges we face going forward. Finally, we discuss some of the important unsolved problems related to the dynamics of the lowermost mantle that can be elucidated in the future by combining observations of seismic anisotropy with geodynamic predictions of lowermost mantle flow.

  PublisherOA PDFDOI

• Flow and Deformation in Earth's Deepest Mantle: Insights From Geodynamic Modeling and Comparisons With Seismic Observations

  Journal of Geophysical Research Solid Earth · 2024-12-01 · 7 citations

  articleOpen accessSenior author

  Abstract The dynamics of Earth's D″ layer at the base of the mantle plays an essential role in Earth's thermal and chemical evolution. Mantle convection in D″ is thought to result in seismic anisotropy; therefore, observations of anisotropy may be used to infer lowermost mantle flow. However, the connections between mantle flow and seismic anisotropy in D″ remain ambiguous. Here, we calculate the present‐day mantle flow field in D″ using 3D global geodynamic models. We then compute strain, a measure of deformation, outside the two large‐low velocity provinces (LLVPs) and compare the distribution of strain with previous observations of anisotropy. We find that, on a global scale, D″ materials are advected toward the LLVPs. The strains of D″ materials generally increase with time along their paths toward the LLVPs and toward deeper depths, but regions far from LLVPs may develop relative high strain as well. Materials in D″ outside the LLVPs mostly undergo lateral stretching, with the stretching direction often aligning with mantle flow direction, especially in fast flow regions. In most models, the depth‐averaged strain in D″ is >0.5 outside the LLVPs, consistent with widespread observations of seismic anisotropy. Flow directions inferred from anisotropy observations often (but not always) align with predictions from geodynamic modeling calculations.

  PublisherOA PDFDOI

• Crustal properties beneath the northeastern United States shaped by past tectonic processes

  Geological Society London Special Publications · 2024-12-16 · 2 citations

  article

  Constraints on the thickness, transitional boundaries, and composition of Earth's crust are pivotal in studying its formation and evolution. We use data from 132 seismic installations throughout the northeastern US to explore how tectonic events, such as orogenesis and rifting, have altered the crust of the northeastern US and southeastern Canada, and to distinguish between Laurentia and the Appalachian terranes. We include data from seismic installations from the NEST and SEISConn experiments, spanning the Laurentia–Appalachian boundary, and present estimates of crustal thickness, V p / V s , and thickness of the transition between crustal and mantle rocks using Ps receiver functions. We find some first-order differences between Laurentia and Appalachian terranes, with Laurentia exhibiting thicker crust ( c. 39 v. c. 33 km) and a broader crust–mantle transition thickness ( c. 3 v. <1.5 km). Average V p / V s values are similar between Laurentia ( c. 1.77) and Appalachian terranes ( c. 1.74); however, we identify anomalous V p / V s in a few regions, including high V p / V s around the Adirondack Mountains and low V p / V s in southern New England. The southern New England region is also anomalous in terms of its systematically thinner crust and sharper crust–mantle transition, which may be a consequence of the formation and collapse of the Acadian altiplano during the mid-to-late Paleozoic.

  PublisherDOI

Recent grants

• Anisotropic Properties of the Mid-lithospheric Discontinuity Beneath Central and Eastern North America

  NSF · $161k · 2014–2016

• Modification of lithospheric structure via subduction, terrane accretion, and rifting: A case study beneath Connecticut

  NSF · $385k · 2018–2023

• CAREER: Geodynamics of subducting slabs in the Earth's deep mantle from seismic anisotropy

  NSF · $540k · 2012–2017

• Collaborative Research: How have orogenesis, rifting, and recent mantle dynamics shaped the lithosphere beneath the New England Appalachians?

  NSF · $271k · 2022–2026

• Collaborative Research: A global examination of the subduction zone flow field from seismic anisotropy

  NSF · $141k · 2009–2013

Frequent coauthors

• Jonathan Wolf

  Planetary Science Institute

  116 shared

• L. S. Wagner

  Carnegie Institution for Science

  70 shared

• John C. Aragon

  Planetary Science Institute

  51 shared

• Neala Creasy

  Los Alamos National Laboratory

  48 shared

• S. L. Beck

  47 shared

• Hernando Tavera

  Instituto Geofísico del Perú

  36 shared

• M. H. Benoit

  U.S. National Science Foundation

  36 shared

• G. Zandt

  University of Arizona

  34 shared

Labs

• Maureen Long's Research GroupPI

Education

• Ph.D. Geophysics, Earth, Atmospheric, and Planetary Sciences

  Massachusetts Institute of Technology

  2006

• B.S. Geology, Earth and Environmental Sciences

  Rensselaer Polytechnic Institute

  2000