Chris Okubo

Chris Okubo
United States Geological Survey | USGS · Astrogeology Science Center

Geological Engineering, PhD

About

121
Publications
15,936
Reads
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2,709
Citations
Citations since 2016
9 Research Items
1226 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Additional affiliations
April 2008 - present
United States Geological Survey
Position
  • Supervisory Research Geophysicist
May 2005 - April 2008
The University of Arizona
Position
  • PostDoc Position
May 2000 - May 2005
University of Nevada, Reno
Position
  • PhD Student

Publications

Publications (121)
Article
Clastic pipes are cylindrical injection features that vertically crosscut bedding with sharp contacts. Terrestrial pipes have cylindrical morphologies, massive or radially graded interiors, and raised outer rims. Increased grain size and subsequent cementation along the more porous edges makes the rims more resistant to weathering. Pipes have cross...
Article
Full-text available
The Colour and Stereo Surface Imaging System (CaSSIS) is the main imaging system onboard the European Space Agency’s ExoMars Trace Gas Orbiter (TGO) which was launched on 14 March 2016. CaSSIS is intended to acquire moderately high resolution (4.6 m/pixel) targeted images of Mars at a rate of 10–20 images per day from a roughly circular orbit 400 k...
Article
Full-text available
Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs)...
Chapter
Geomorphic confirmation for a putative ancient Mars ocean relies on analog comparisons of coastal-like features such as shoreline feature attributes and temporal scales of process formation. Pleistocene Lake Bonneville is one of the few large, geologically young, terrestrial lake systems that exemplify well-preserved shoreline characteristics that...
Article
Small edifice features that are less than a few kilometers in diameter and up to a few hundred meters in height are widely distributed in Chryse Planitia on Mars. They exhibit a broad range of morphological properties that are here classified as Type 1 (steep-sided cones typically with a summit crater), Type 2 (nearly flat features with single or m...
Article
Populations of distinctive knobs, rings and lobate structures are observed in the Candor and Coprates Chasmata regions of Mars. To interpret the formation mechanisms of these landforms, I investigate their morphologies, facies, superposition and crosscutting relationships using data from the High Resolution Imaging Science Experiment (HiRISE) and t...
Article
Ritchey crater is a ∼79 km diameter complex crater near the boundary between Hesperian ridged plains and Noachian highland terrain on Mars (28.8°S, 309.0°E) that formed after the Noachian. High Resolution Imaging Science Experiment (HiRISE) images of the central peak reveal fractured massive bedrock and megabreccia with large clasts. Compact Reconn...
Article
More than 100 pit craters in the Tharsis region of Mars exhibit morphologies, diameters, and thermal behaviors that diverge from the much larger bowl-shaped pit craters that occur in most regions across Mars. These Atypical Pit Craters (APCs) generally have sharp and distinct rims, vertical or overhanging walls that extend down to their floors, sur...
Conference Paper
Full-text available
Near-vertical scarps in paterae reveal cross-sections of Io’s upper crust. Numerical modeling is used to quantify material strength and constrain composition.
Conference Paper
Spectrophotometric characterization of various Mars analogs in the VIS spectral range and implication for remote-sensing studies of the martian surface.
Article
Full-text available
The near-verical slopes of scarps on Io provide clues into the upper crust. We investigate compositional constraints using numerical slope stability modeling.
Conference Paper
Introduction: The north polar layered deposits (NPLD) are characterized by a ~3-km thick stack of H2O ice/dust layers covered seasonally by a CO2 frost layer [1]. These deposits are exposed in large concen-tric spiral troughs thought to be formed by katabatic winds coming off the north pole [2,3], ablation and sublimation. The NPLD stratigraphy is...
Article
[1] We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples t...
Article
A number of observations of the Martian surface rely on the analysis of solar light reflected by the surface. The photometric properties of the materials that compose the uppermost layer of Mars' surface are thus crucial parameters for detailed analyses of the remote-sensing datasets. Whereas laboratory measurements of the bidirectional reflectance...
Article
Results of the first 1:20,000-scale geologic map through the central part of the Candor Colles, in west Candor Chasma, are presented here.
Conference Paper
Comparisons of terrestrial pipes with massive circular features in west Candor Chasma suggest synsedimentary deformation prior to lithification.
Conference Paper
Full-text available
We show that in the Herschel Crater the dominant winds from the north are able to keep the ripples and dunes active in the actual atmospheric conditions.
Article
We are mapping the central uplifts of large craters and reconstructing the pre-impact stratigraphy, to better understand the Noachian stratigraphy of Mars.
Article
Kalaupapa Peninsula, along the northern coast of East Moloka‘i volcano, is a remarkably well-preserved example of rejuvenated-stage volcanism from a Hawaiian volcano. Mapping of lava flows, vents and other volcanic constructs reveals a diversity of landforms on this small monogenetic basaltic shield. The late-stage lava distributary system of this...
Article
Full-text available
Volcanic ash is thought to comprise a large fraction of the Martian equatorial layered deposits and much new insight into the process of faulting and related fluid flow in these deposits can be gained through the study of analogous terrestrial tuffs. This study identifies a set of fault-related processes that are pertinent to understanding the evol...
Article
High-resolution structural mapping within the layered deposits in west Candor Chasma provide the first detailed documentation of fault-related damage zones on Mars. These damage zones are interpreted to be largely composed of deformation bands.
Conference Paper
Our ongoing investigation of small mound features in Chryse Planitia, Mars, using imaging and spectral data is in general agreement with a mud volcano hypothesis but some notable characteristics uncommon in terrestrial counterparts are identified.
Article
The discovery of gully features on Mars has led to renewed interest in hillslope processes on that planet, in particular mass movement and the morphologies that it produces. Mass movement is a collection of gravity-driven processes that act to move materials down a hillslope. Here, we examine how mass movements on hillslopes may be expected to diff...
Article
The equatorial layered deposits on Mars exhibit abundant evidence for the sustained presence of groundwater, and therefore insight into past water-related processes may be gained through the study of these deposits. Pyroclastic and evaporitic sediments are two broad lithologies that are known or inferred to comprise these deposits. Investigations i...
Conference Paper
Full-text available
HiSCI has been chosen for the payload of the ExoMars Trace Gas Orbiter (TGO), a joint ESA/NASA mission scheduled to arrive at Mars in 2016 [1]. There are 3 major HiSCI partners: (1) the telescope assembly will be built in Switzerland overseen by the University of Bern; (2) the overall design, electronics, and integration will be by Ball Aerospace i...
Article
Full-text available
The formation process of recent gullies on Mars is currently under debate. This study aims to discriminate between the proposed formation processes - pure water flow, debris flow and dry mass wasting - through the application of geomorphological indices commonly used in terrestrial geomorphology. High-resolution digital elevation models (DEMs) of E...
Conference Paper
Full-text available
The High-resolution Stereo Color Imager (HiSCI), chosen for the payload of the ExoMars Trace Gas Orbiter (TGO), is described.
Conference Paper
Full-text available
Interpretations of shorelines and landforms on Mars can be guided by terrestrial analog studies to generate a Mars hydrograph with the potential to provide a crucial planetary reference datum.
Article
HiRISE DTMs are produced at 1 m/px and 2 m/px, depending on source image mode. The procedure used to create the DTMs and their associated orthoimages is described here, as well as the products being made available via the PDS starting in 2010.
Article
Full-text available
Utah offers spectacular geologic features and valuable analog environments and processes for Mars studies. Horizontal strata of the Colorado Plateau are analogous to Mars because the overprint of plate tectonics is minimal, yet the effects of strong ground motion from earthquakes or impacts are preserved in the sedimentary record. The close proximi...
Article
The value of slope stability analyses for gaining insight into the geologic conditions that would facilitate the growth of gully alcoves on Mars is demonstrated in Gasa crater. Two-dimensional limit equilibrium methods are used in conjunction with high-resolution topography derived from stereo High Resolution Imaging Science Experiment (HiRISE) ima...
Article
In order to gain more insight into the effect of faulting on the potential for fluid flow through tuff, fault-related changes in host rock permeability are investigated within the Joe Lott Tuff Member of the Mount Belknap Volcanics in southwestern Utah. The study area is located along the southern flank of the Clear Creek downwarp in the Sevier Val...
Article
Full-text available
Deformation of sedimentary rocks is widespread within Valles Marineris, characterized by both plastic and brittle deformation identified in Candor, Melas, and Ius Chasmata. We identified four deformation styles using HiRISE and CTX images: kilometer-scale convolute folds, detached slabs, folded strata, and pull-apart structures. Convolute folds are...
Article
Full-text available
1] Determining the rock properties that permit or impede the growth of compaction bands in sedimentary sequences is a critical problem of importance to studies of strain local-ization and characterization of subsurface geologic reser-voirs. We determine the porosity and average grain size of a sequence of stratigraphic layers of Navajo Sandstone th...
Article
Structural geology is an integral part of planetary science. Planetary structures provide the framework for determining the character and sequence of crustal deformation while simultaneously establishing the observational basis required to test geodynamic hypotheses for the deformation of planetary and satellite lithospheres. The availability of da...
Article
The structural geology of an outcropping of layered sedimentary deposits in southwest Candor Chasma is mapped using two adjacent high-resolution (1 m/pixel) HiRISE digital elevation models and orthoimagery. Analysis of these structural data yields new insight into the depositional and deformational history of these deposits. Bedding in non-deformed...
Conference Paper
Full-text available
Utah has many ancient and modern examples of diverse terrestrial environments and geomorphic expressions. These examples are valuable resources for exploratory and robotic missions to Mars.
Article
We present quantitive geomorphic analyses of high resolution digital elevation models of gully systems on Mars. Our methods allowed good discrimination between processes on Earth, and on Mars debris flow is identified as the dominant process.
Article
The near-vertical walls of paterae on Io require that the upper crust be composed of material with significant cohesion, such as basalt or cold sulfur. We continue to investigate if low-density sulfur/sulfur dioxide snow is also an option.
Article
Morphological features on the western floor of Miyamoto crater in southwestern Meridiani Planum, Mars, are suggestive of past fluvial activity. Imagery from the High Resolution Imaging Science Experiment (HiRISE) gives a detailed view of raised curvilinear features that appear to represent inverted paleochannel deposits. The inverted terrain appear...
Article
The morphologies of some martian gullies appear similar to terrestrial features associated with debris flow initiation, erosion, and deposition. On Earth, debris flows are often triggered by shallow subsurface throughflow of liquid water in slope-mantling colluvium. This flow causes increased levels of pore pressure and thus decreased shear strengt...
Article
The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5–6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25...
Article
High Resolution Imaging Science Experiment (HiRISE) imagery and digital elevation models of the Candor Chasma region of Valles Marineris, Mars, reveal prominent and distinctive positive-relief knobs amidst light-toned layers. Three classifications of knobs, Types 1, 2, and 3, are distinguished from a combination of HiRISE and Thermal Emission Imagi...
Chapter
This book describes the tectonic landforms resulting from major internal and external forces acting on the outer layers of solid bodies throughout the Solar System. It presents a detailed survey of tectonic structures at a range of length scales found on Mercury, Venus, the Moon, Mars, the outer planet satellites, and asteroids. A diverse range of...
Article
[1] The SHARAD instrument on the Mars Reconnaissance Orbiter detects subsurface interfaces beneath lava flow fields northwest of Ascraeus Mons. The interfaces occur in two locations; a northern flow that originates south of Alba Patera, and a southern flow that originates at the rift zone between Ascraeus and Pavonis Montes. The northern flow has p...
Article
Spacecraft continue to send back extraordinary amounts of data from Mars leaving scientists with the considerable task of analyzing an ever-increasing wealth of information. There are abundant uses for coregistered topography and images, but coregistering various datasets can be time-consuming and labor-intensive. We have developed a set of C-shell...
Article
Deformation of sedimentary rocks is widespread within Valles Marineris with many occurrences of both brittle and plastic deformation identified in Melas, Candor and Ius Chasmata. Using HiRISE and CTX images, we identify four styles of deformation, contorted beds, blocky deposits, folded strata and fragmented strata. Contorted beds are detached roun...
Article
There have been numerous observations of long, relatively sinuous, positive relief landforms on Mars that appear morphologically similar to inverted channel deposits (ICDs) on Earth that represent exhumed fluvial sediments. ICDs initially form as bed sediments within active stream channels that subsequently become cemented, commonly by carbonates,...
Conference Paper
We present an inventory of geomorphic analogues for Lake Bonneville and Mars, with focus on potential standing-water features. The goal is to understand water as a geomorphic agent at a variety of temporal and spatial scales.
Article
SHARAD detects subsurface interfaces associated with the distal parts of smooth flows northwest of Ascraeus Mons. The dielectric properties of these flows are consistent with basaltic lavas.
Article
We compare morphometric characteristics of terrestrial gullies associated with debris flows with a subset of martian gullies to test the hypothesis that these martian gullies are formed by saturation and failure of the regolith.
Article
Curvilinear ridges on the western floor of Miyamoto crater have similar characteristics to positive relief channel deposits seen on Earth near Green River, UT that are interpreted as exhumed, inverted, fluvial paleochannel deposits.
Article
Full-text available
High-resolution imagery reveals unprec- edented lines of evidence for the presence of deformation band clusters in layered sedi- mentary deposits in the equatorial region of Mars. Deformation bands are a class of geologic structural discontinuity that is a precursor to faults in clastic rocks and soils. Clusters of deformation bands, consisting of...
Article
The SHARAD (shallow radar) sounding radar on the Mars Reconnaissance Orbiter detects subsurface reflections in the eastern and western parts of the Medusae Fossae Formation (MFF). The radar waves penetrate up to 580 m of the MFF and detect clear subsurface interfaces in two locations: west MFF between 150 and 155° E and east MFF between 209 and 213...
Article
High Resolution Imaging Science Experiment (HiRISE) imagery and digital elevation models of the Candor Chasma region of Valles Marineris, Mars, reveal prominent and distinctive positive-relief knobs amidst light-toned layers. Three classifications of knobs, Types 1, 2, and 3, are distinguished from a combination of HiRISE and Thermal Emission Imagi...
Article
Full-text available
North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiting Mars has discovered new, dramatic examples that Mars' CO2-dominated seasonal volatile cycle is not limited to quiet deposition and sublimation of frost. In early northern martian spring, 2008, HiRISE captured several cases of CO2 frost and dust casca...
Article
Full-text available
High-resolution topography generated from stereo HiRISE (High-Resolution Imaging Science Experiment) imagery reveals the meter-scale structure of interior layered deposits (ILD) in southwest Candor Chasma. This study seeks to determine the age of the local ILD relative to any normal faults that can be attributed to chasma formation. The study area...
Article
Displacement–length data from faults, joints, veins, igneous dikes, shear deformation bands, and compaction bands define two groups. The first group, having a power-law scaling relation with a slope of n = 1 and therefore a linear dependence of maximum displacement and discontinuity length (Dmax = γL), comprises faults and shear (non-compactional o...