About

Ramon Arrowsmith has been a faculty member at Arizona State University since 1995, where he teaches courses in field geology, structural geology, geomorphology, and computers in earth and space exploration. With over 35 years of experience, his research focuses on earthquake geology, paleoseismology, and the geomorphology of fault zones, emphasizing their history of activity and hazards. He is a cofounder and co-PI of the OpenTopography project, a portal providing access to a large collection of high-resolution topography data, and has led numerous short courses, workshops, and activities centered on high-resolution topographic data and tectonic geomorphology. His research group investigates active faulting, earthquake geology, tectonic geomorphology, and the geological framework for human origins. Throughout his career, he has held various administrative roles within the ASU School of Earth and Space Exploration, including associate chair, associate director of graduate studies, deputy director, and interim director. He is also an affiliate of the Institute of Human Origins Research at ASU. His educational background includes a Ph.D. in Geological and Environmental Sciences from Stanford University and a B.S. in Geology and Spanish from Whittier College. Arrowsmith has received numerous awards for his teaching and research, including recognition from the American Geophysical Union and the Geological Society of America, and has served on several national and international committees related to earthquake research and geosciences.

Research topics

• Geology
• Artificial Intelligence
• Engineering
• Computer Science
• Seismology
• Remote sensing
• Structural engineering
• Geography
• Oceanography
• Geomorphology
• Environmental science
• Cartography
• Marine engineering

Selected publications

• DOES A GRAY PUMICE RICH LAPILLI TUFF FROM A FOSSIL LOCATION IN CENTRAL LEE ADOYTA, WITHIN LGRP, GEOCHEMICALLY CORRELATE TO A KNOWN DATED TUFF CALLED THE GURUMAHA TUFF?

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

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  PublisherDOI

• President's Medal: Advancing Geoscience Research and Education with Open Topographic Data and Tools

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

  article
  PublisherDOI

• Age Model and Depositional Environments of the Pliocene Northern Awash Cores of the Hominin Sites and Paleolakes Drilling Project (HSPDP)

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

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  PublisherDOI

• New discoveries of Australopithecus and Homo from Ledi-Geraru, Ethiopia

  Nature · 2025-08-13 · 10 citations

  articleOpen access

  The time interval between about three and two million years ago is a critical period in human evolution—this is when the genera Homo and Paranthropus first appear in the fossil record and a possible ancestor of these genera, Australopithecus afarensis, disappears. In eastern Africa, attempts to test hypotheses about the adaptive contexts that led to these events are limited by a paucity of fossiliferous exposures that capture this interval. Here we describe the age, geologic context and dental morphology of new hominin fossils recovered from the Ledi-Geraru Research Project area, Ethiopia, which includes sediments from this critically underrepresented period. We report the presence of Homo at 2.78 and 2.59 million years ago and Australopithecus at 2.63 million years ago. Although the Australopithecus specimens cannot yet be identified to species level, their morphology differs from A. afarensis and Australopithecus garhi. These specimens suggest that Australopithecus and early Homo co-existed as two non-robust lineages in the Afar Region before 2.5 million years ago, and that the hominin fossil record is more diverse than previously known. Accordingly, there were as many as four hominin lineages living in eastern Africa between 3.0 and 2.5 million years ago: early Homo1, Paranthropus2, A. garhi3, and the newly discovered Ledi-Geraru Australopithecus. Hominin fossils from the Ledi-Geraru Research Project area, Ethiopia, suggest that early Homo and Australopithecus species co-existed in the region more than 2.5 million years ago.

  PublisherOA PDFDOI

• Advancing Analysis of 2D and 3D Scenes Using Deep Learning and Physics-engines

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

  article1st authorCorresponding
  PublisherDOI

• A systematic approach to mapping tectonic faults and documenting supporting geomorphology

  Geosphere · 2025-01-17 · 2 citations

  articleOpen access

  Abstract Mapping tectonic faults is challenging because mapping approaches are not standardized and some evidence for faulting is ambiguous due to surface processes that obscure the geomorphology. We developed and evaluated a new systematized approach for mapping faults and documenting geomorphic evidence based on desktop mapping using remote sensing data. Our approach works as a teaching tool to introduce fault mapping and in industry settings to establish consistent documentation. Using our approach, a mapper maps the landscape morphology, geomorphology, and surficial geology. The mapper uses the geomorphic indicator ranking approach to document the geomorphic indicators that support faulting such as scarps, triangular facets, and deflected streams. The resulting fault maps facilitate straightforward dissemination of information and build toward more accurate depictions of fault traces, which support understanding fault processes and predicting coseismic rupture location in a future earthquake. We evaluated our mapping approach as follows. (1) We qualified the geomorphology that best predicts future rupture location as having the lowest geomorphic indicator-to-rupture separation distance. Of the features tested, cut or offset alluvial fans, fault scarps, and lineaments performed the best. (2) We found similarities in the fault confidence rankings chosen by the mappers and those calculated from the mapped geomorphology. (3) To explore best practices in fault mapping, we conducted listening sessions with 18 participants and found that terminology and mapping process vary by experience level. More-experienced mappers tend to use more technical terms to describe the geomorphology while less-experienced mappers use vague descriptions and generalize nearby features.

  PublisherOA PDFDOI

• Virtual Shake Robot: Simulating Dynamics of Precariously Balanced Rocks for Overturning and Large-displacement Processes

  Seismica · 2024-01-16 · 8 citations

  articleOpen access

  Understanding the dynamics of precariously balanced rocks (PBRs) is important for seismic hazard analysis and rockfall prediction. Utilizing a physics engine and robotic tools, we develop a virtual shake robot (VSR) to simulate the dynamics of PBRs during overturning and large-displacement processes. We present the background of physics engines and technical details of the VSR, including software architecture, mechanical structure, control system, and implementation procedures. Validation experiments show the median fragility contour from VSR simulation is within the 95% prediction intervals from previous physical experiments, when PGV/PGA is greater than 0.08 s. Using a physical mini shake robot, we validate the qualitative consistency of fragility anisotropy between the VSR and physical experiments. By overturning cuboids on flat terrain, the VSR reveals the relationship between fragility and geometric dimensions (e.g., aspect and scaling ratios). The ground motion orientation and lateral pedestal support affect PBR fragility. Large-displacement experiments estimate rock trajectories for different ground motions, which is useful for understanding the fate of toppled PBRs. Ground motions positively correlate with large displacement statistics such as mean trajectory length, mean largest velocity, and mean terminal distance. The overturning and large displacement processes of PBRs provide complementary methods of ground motion estimation.

  PublisherOA PDFDOI

• Surface Rupture of the 2008 <i>M</i> _w 6.6 Nura Earthquake: Triggered Flexural‐Slip Faulting in the Pamir‐Tien Shan Collision Zone

  Tectonics · 2024-09-01 · 5 citations

  articleOpen access

  Abstract This study investigates the intricate relationship between earthquake sources and seismogenic surface ruptures in a complex tectonic setting with active faults in the continental collision zone between the southern Tien Shan and the northern Pamir Mountains in Central Asia. The study focuses on the 2008 M w 6.6 Nura earthquake along the Pamir Frontal Thrust, where the seismogenic surface rupture occurred unexpectedly within the footwall and 10 km away from the source thrust fault. This discrepancy raises questions about the interactions and potential trigger mechanisms between tectonic structures during earthquake rupture. Using unmanned aerial vehicle photography and field inspection, our investigation integrates detailed fault‐zone mapping with tectono‐geomorphic observations to unravel potential interactions between subsurface structures and surface‐deformation phenomena. Our findings suggest that a combination of slip along deep‐seated basement faults and remotely triggered flexural slip within folded Paleogene strata led to surface rupture of overlying Quaternary glacial deposits. Geomorphological and geochronological analyses coupled with systematic displacement measurements furthermore reveal evidence of similar past ruptures within the regional fault system, suggesting a recurrence interval of 1.7 kyr and a Holocene vertical offset rate of 0.4 mm/yr. The analysis of the Nura rupture zone contributes significantly to evaluate linkages between surface and subsurface structures regarding fault‐zone behavior and seismic hazard assessments. Importantly, our results highlight the critical role of on‐site investigations in regions with poorly defined surface ruptures, where misinterpretation may lead to the underestimation of the impact of seismic events and limitations in assessing earthquake history and strain accumulation.

  PublisherDOI

• Assessing the effects of long-term landscape evolution on the overburden of deep repository sites: application to northern Switzerland

  2024-03-09

  preprintOpen access

  The safety assessment of radioactive waste repositories requires scenarios and forecasts of the erosional, climatic, and tectonic future evolution. One of the major challenges in the assessment of long-term landscape evolution for safety is that the relevant processes, models and model parameters are subject to a range of significant uncertainties. Assessments should provide the full range of conceivable developments using the best available scientific knowledge. Here, we present an assessment framework for future erosion with a rigorous uncertainty management. The approach anticipates erosion from fluvial, hillslope, and glacial processes over a timescale of 105-106 years. Uncertainties are addressed in a hybrid way, using probabilistic methods in combination with a scenario approach, whereby the chosen scenarios cover a wide range of possibilities. A protocol was followed to derive model parameter uncertainties that respect individual estimates of experts. The entire process is accompanied by a sensitivity analysis. We used the workflow to assess erosion in Northern Switzerland over the next million years. The results serve as input to site a deep geological repository for nuclear waste in Switzerland and to demonstrate its long-term safety.

  PublisherDOI

• Tectonic Landform and Lithologic Age Impact Uncertainties in Fault Displacement Hazard Models

  Geophysical Research Letters · 2024-08-24 · 7 citations

  articleOpen access

  Abstract Tectonic landforms and surficial lithologic age are essential data for producing quality late Quaternary fault maps and predicting coseismic fault rupture location before an earthquake. However, we lack a clear understanding of the relationship between tectonic landforms and shallow earthquake processes and how lithologic age relates to landform preservation. We assess how fault location error (rupture‐to‐fault separation distance) and coseismic displacement residual (difference between observed and predicted coseismic displacement) vary with tectonic landform and lithologic age for four historical earthquakes. Certain tectonic landforms identified before these earthquakes correlate with lower fault location errors and median displacements below model predictions. Faults cutting Holocene units exhibit the largest location errors, reflecting surface processes that erode or bury fault evidence. This study shows that tectonic landforms and lithologic age have a significant impact on fault location uncertainty and coseismic displacement, which should be considered in fault mapping and fault displacement assessment.

  PublisherOA PDFDOI

Frequent coauthors

• C. J. Crosby

  16 shared

• O. Zielke

  12 shared

• Edwin Nissen

  University of Victoria

  8 shared

• Viswanath Nandigam

  8 shared

• S. O. Akciz

  8 shared

• M. E. Oskin

  University of California, Davis

  8 shared

• D. E. Haddad

  8 shared

• Chelsea Scott

  Arizona State University

  7 shared

Education

• Ph.D., Geological and Environmental Sciences

  Stanford University

  1995

• B.S., Geology and Spanish

  Whittier College

  1989

Awards & honors

• Open Science Recognition Prize (for OpenTopography along wit…
• Faculty Service Achievement Award, Arizona State University…
• Paul G. Silver Award for Outstanding Scientific Service, Ame…
• Arizona State University School of Earth and Space Explorati…
• Fellow, Geological Society of America 2009