Time filter

Source Type

Shirzaei M.,University of California at Berkeley | Shirzaei M.,Arizona State University | Burgmann R.,University of California at Berkeley | Foster J.,Hawaii Institute of Geophysics and Planetology | And 2 more authors.
Earth and Planetary Science Letters | Year: 2013

The Hilina Fault System (HFS) is located on the south flank of Kilauea volcano and is thought to represent the surface expression of an unstable edifice sector that is active during seismic events such as the 1975 Kalapana earthquake. Despite its potential for hazardous landsliding and associated tsunamis, no fault activity has yet been detected by means of modern geodetic methods, since the 1975 earthquake. We present evidence from individual SAR interferograms, as well as cluster analysis and wavelet analysis of GPS and InSAR time series, which suggest an inferred differential motion at HFS. To investigate the effect of atmospheric delay on the observed differential motion, we implement a statistical approach using wavelet transforms. We jointly analyze InSAR and continuous GPS deformation data from 2003 to 2010, to estimate the likelihood that the subtle time-dependent deformation signal about the HFS scarps is not associated with the atmospheric delay. This integrated analysis reveals localized deformation components in the InSAR deformation time series that are superimposed on the coherent motion of Kilauea's south flank. The statistical test suggests that at 95% confidence level, the identified differential deformation at HFS is not due to atmospheric artifacts. Since no significant shallow seismicity is observed over the study period, we suggest that this deformation occurred aseismically. © 2013 Elsevier B.V.

Horozal S.,Korea Institute of Geoscience and Mineral Resources | Kim G.Y.,Korea Institute of Geoscience and Mineral Resources | Bahk J.J.,Korea Institute of Geoscience and Mineral Resources | Wilkens R.H.,Hawaii Institute of Geophysics and Planetology | And 3 more authors.
Marine and Petroleum Geology | Year: 2015

We analyzed the data consist of core digital images and X-rays, core-logs, LWD (logging-while-drilling), and sediment grain-size from the second Ulleung Basin Gas Hydrate Expedition (UBGH2) in the East Sea. Core digital images and X-rays were spliced as a complete composite core in meters below seafloor (mbsf) for five sites; UBGH2-1_1 (Hole D), 2_1 (B), 2_2 (B), 2-6 (B) and 2-10 (C-D), and were correlated with the core-log and LWD measurements showing that possible gas hydrate bearing layers are between the depths of about 60-180mbsf at these sites. Bulk densities generally increase with depth from 1.3 to 2.0g/cm3 in LWD data, and from 1.1 to 1.8g/cm3 onboard which measured lower than in-situ. Gas hydrate bearing sediments respond with an increase of LWD densities (1.4-1.6g/cm3) and a decrease in core-logs (1.1-1.4g/cm3). P-wave velocity values of LWD increase (1400 to 1700m/s) with depth for non-reservoirs, and are high (1500 and 2000m/s) within the gas hydrate bearing intervals depending on the hydrate saturations. Resistivity values logged onboard range from less than 1.0 to over 10.0Ω-m, while LWD records are around 1.0Ω-m and between 5.0 and 30.0Ω-m in background sediments and possible gas hydrate reservoirs, respectively. High resistivity values were observed (5.0-30.0Ω-m) within coarse-grained turbidites (mean grain-size between 2.9 and 5.1ϕ laminated sandy mud or muddy sands). Medium resistivities were observed (5.0Ω-m) within the silt-dominant hemi-pelagic and turbiditic sediments (5.1-7.4ϕ crudely laminated, bioturbated, homogeneous sand, and disintegrated sand and sandy mud facies) bearing pore-filling gas hydrates, or disseminated gas hydrates either formed in pores or small fractures of fine-grained sediments. Core-log measurements are highly fluctuating and sensitive but mostly lower (e.g., density and resistivity) than LWD records. © 2014 Elsevier Ltd.

Rudraswami N.G.,National Institute of Oceanography of India | Prasad M.S.,National Institute of Oceanography of India | Nagashima K.,Hawaii Institute of Geophysics and Planetology | Jones R.H.,University of New Mexico
Geochimica et Cosmochimica Acta | Year: 2015

Most olivine relict grains in cosmic spherules selected for the present study are pristine and have not been disturbed during their atmospheric entry, thereby preserving their chemical, mineralogical and isotopic compositions. In order to understand the origin of the particles, oxygen isotope compositions of relict olivine grains in twelve cosmic spherules collected from deep sea sediments of the Indian Ocean were studied using secondary ion mass spectrometry. Most of the data lie close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line, with δ17O ranging from -5‰ to 0‰. The data overlap oxygen isotopic compositions of chondrules from carbonaceous chondrites such as CV, CK, CR and CM, which suggests that chondrules from carbonaceous chondrites are the source of relict grains in cosmic spherules. Chemical compositions of olivine in cosmic spherules are also very similar to chondrule olivine from carbonaceous chondrites. Several olivine relict grains in three cosmic spherules are 16O-rich (δ17O -21.9‰ to -18.7‰), similar to oxygen isotopic compositions observed in calcium aluminum rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and some porphyritic chondrules from carbonaceous chondrites. These grains appear to have recorded the initial oxygen isotopic composition of the inner solar nebula. Three olivine grains from two cosmic spherules have δ18O values >+20‰, which could be interpreted as mixing with stratospheric oxygen during atmospheric entry. © 2015 Elsevier Ltd.

Wheat C.G.,University of Alaska Fairbanks | Jannasch H.W.,Monterey Bay Aquarium Research Institute | Fisher A.T.,University of California at Santa Cruz | Becker K.,University of Miami | And 2 more authors.
Geochemistry, Geophysics, Geosystems | Year: 2010

Integrated Ocean Drilling Program (IODP) Hole 1301A was drilled, cased, and instrumented with a long-term, subseafloor observatory (CORK) on the eastern flank of the Juan de Fuca Ridge in summer 2004. This borehole is located 1 km south of ODP Hole 1026B and 5 km north of Baby Bare outcrop. Hole 1301A penetrates 262 m of sediment and 108 m of the uppermost 3.5 Ma basaltic basement in an area of warm (64C) hydrothermal circulation. The borehole was instrumented, and those instruments were recovered 4 years later. Here we report chemical data from two continuous fluid samplers (OsmoSamplers) and temperature recording tools that monitored changes in the state of borehole (formation) fluids. These changes document the effects of drilling, fluid overpressure and flow, seawater-basalt interactions, and microbial metababolic activity. Initially, bottom seawater flowed into the borehole through a leak between concentric CORK casing strings. Eventually, the direction of flow reversed, and warm, altered formation fluid flowed into the borehole and discharged at the seafloor. This reversal occurred during 1 week in September 2007, 3 years after drilling operations ceased. The composition of the formation fluid around Hole 1301A generally lies within bounds defined by springs on Baby Bare outcrop (to the south) and fluids that discharged from Hole 1026B (to the north); deviations likely result from reactions with drilling products. Simple conservative mixing of two end-member fluids reveals reactions occurring within the crust, including nitrate reduction presumably by denitrifying microbes. The observed changes in borehole fluid composition provide the foundation for a conceptual model of chemical and microbial change during recharge of a warm ridge-flank hydrothermal system. This model can be tested through future scientific ocean drilling experiments. Copyright 2010 by the American Geophysical Union.

Wright R.,Hawaii Institute of Geophysics and Planetology | Garbeil H.,Hawaii Institute of Geophysics and Planetology | Davies A.G.,Jet Propulsion Laboratory
Journal of Geophysical Research: Solid Earth | Year: 2010

The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing-1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4-2.5 μm region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wave bands available allows for the assumption of more complex flow surface temperature distributions in the radiance-to-temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well-characterized calibration target, a time series of three Hyperion images of an active lava flow acquired during a 4 day period at Mount Etna, Sicily, as well as a lava flow erupted at Nyamuragira, Democratic Republic of Congo. The results provide insights into the temperature-radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission. Copyright © 2010 by the American Geophysical Union.

Takigawa A.,University of Tokyo | Takigawa A.,Kyoto University | Tachibana S.,University of Tokyo | Tachibana S.,Hokkaido University | And 5 more authors.
Geochimica et Cosmochimica Acta | Year: 2014

Corundum, the thermodynamically stable phase of alumina (Al2O3), is one of the most refractory dust species to condense around evolved stars. Presolar alumina in primitive chondrites has survived various kinds of processing in circumstellar environments, the interstellar medium (ISM), the Sun's parent molecular cloud, and the protosolar disk. The morphology and crystal structure of presolar alumina grains may reflect their formation and evolution processes, but the relative importance of these two types of processes is poorly understood. In this study, we performed detailed morphological observations of 185 alumina grains extracted from unequilibrated ordinary chondrites (Semarkona, Bishunpur, and RC075). We also performed electron back-scattered diffraction analyses of 122 grains and oxygen isotopic analyses of 107 grains. Dissolution experiments on corundum and transition alumina phases were carried out to examine the possibility of the alteration of surface structures of alumina grains by the chemical separation procedures of chondrites. The average size of the alumina grains was 1μm, and neither whiskers nor extremely flat grains were observed. About one-third of the grains had smooth surfaces, while ~60% of the grains had rough surfaces with 10-100nm-sized fine structures. The rough-surface grains have varieties of morphology and crystallinity, suggesting that the rough surface structures are secondary in origin. Electron back-scattered diffraction patterns from 95% of alumina grains matched with α-Al2O3 (corundum), and more than 75% of the alumina grains are single crystals of corundum. Nine presolar alumina grains with anomalous oxygen isotopic compositions were found among 107 alumina grains, and most of them were characterized by rough surface structures. While most of the presolar alumina grains were corundum, the relative abundance of amorphous or low-crystallinity grains is higher in presolar alumina grains than in solar alumina grains. The dissolution experiments showed that all phases except for corundum dissolved during the acid treatments of chondrites. This suggests that smooth surface structures of corundum grains were originally formed in space, and that original surfaces of alumina that had been damaged by energetic particle irradiation in the ISM or the protosolar disk were lost during chemical separations to form the rough surface structures, and that amorphous or low-crystallinity alumina grains in chondrites have acid-resistant structures different from sol-gel-synthesized amorphous alumina. The present results also imply the possible presence of acid-soluble alumina phases, undiscovered by chemical separations, in chondrites. © 2013 Elsevier Ltd.

Wright R.,Hawaii Institute of Geophysics and Planetology | Blackett M.,Coventry University | Hill-Butler C.,Coventry University
Geophysical Research Letters | Year: 2015

We present satellite measurements of the thermal flux observed from 95 active volcanoes, based on observations made daily over the past 15 years by NASA's Terra and Aqua Moderate Resolution Imaging Spectroradiometer sensors. Excursions from an apparent baseline level of thermal emission are attributable to episodic lava-flow-forming eruptions. Highest average intensity was associated with the July 2001 eruption of Etna, Italy, which radiated an average of 2.5 × 109 W over 23 days. However, recent fissure eruptions in the Afar Rift have attained higher average intensities of 2.4-4.4 × 109 W, albeit for days, not weeks. The largest magnitude eruption was the ongoing eruption of Bardarbunga, Iceland, which radiated 2.6 × 1016 J. Ki¯lauea, Hawai'i, has radiated the most energy since 2000, although the lava lake at Nyiragongo, Democratic Republic of Congo, comes a close second. Time series analysis reveals evidence for periodicity in radiant flux at some volcanoes but not at others. © 2015. American Geophysical Union. All Rights Reserved.

Wright R.,Hawaii Institute of Geophysics and Planetology | Lucey P.,Hawaii Institute of Geophysics and Planetology | Crites S.,Hawaii Institute of Geophysics and Planetology | Horton K.,Hawaii Institute of Geophysics and Planetology | And 2 more authors.
Acta Astronautica | Year: 2013

The Thermal Hyperspectral Imager (THI) is a low cost, low mass, power efficient instrument designed to acquire hyperspectral remote sensing data in the long-wave infrared. The instrument has been designed to satisfy mass, volume, and power constraints necessary to allow for its accommodation in a 95 kg micro-satellite bus, designed by staff and students at the University of Hawai'i. THI acquires approximately 30 separate spectral bands in the 8-14 μm wavelength region, at 16 wavenumber resolution. Rather than using filtering or dispersion to generate the spectral information, THI uses an interferometric technique. Light from the scene is focused onto an uncooled microbolometer detector array through a stationary interferometer, causing the light incident at each detector at any instant in time to be phase shifted by an optical path difference which varies linearly across the array in the along-track dimension. As platform motion translates the detector array in the along-track direction at a rate of approximately one pixel per frame (the camera acquires data at 30 Hz) the radiance from each scene element can be sampled at each OPD, thus generating an interferogram. Spectral radiance as a function of wavelength is subsequently obtained for each scene element using standard Fourier transform techniques. Housed in a pressure vessel to shield COTS parts from the space environment, the total instrument has a mass of 15 kg. Peak power consumption, largely associated with the calibration procedure, is <90 W. From a nominal altitude of 550 km the resulting data would have a spatial resolution of approximately 300 m. Although an individual imaging event yields approximately 1 Gbit of raw uncompressed data, onboard processing (to convert the interferograms into a conventional spectral hypercube) can reduce this to tens of Mega bits per scene. In this presentation we will describe (a) the rationale for the project, (b) the instrument design, and (c) how the data are processed. Finally we will present data acquired by THI on a laboratory microscope stage to demonstrate the spectro-radiometric quality of the data that the instrument can provide. © 2013 Elsevier Ltd. All rights reserved.

Zinin P.,Hawaii Institute of Geophysics and Planetology | Tatsumi-Petrochilos L.,University of Hawaii at Manoa | Bonal L.,Hawaii Institute of Geophysics and Planetology | Acosta T.,Hawaii Institute of Geophysics and Planetology | And 3 more authors.
American Mineralogist | Year: 2011

A systematic study of the Raman spectra of the titanomagnetite solid-solution series (Fe3-xTixO4) for x = ̃0.0, 0.2, 0.4, and 0.6 has been conducted. The samples showed combinations of five previously predicted Raman peaks at ̃190, 310, 460, 540, and 670 cm-1 that correspond to vibrational modes with T2g(1), Eg, T2g(3), T2g(2), and A1g, respectively. The calibration of Raman spectra for titanomag-netite with known values of Ti concentrations reveals a strong dependence of relative intensity for the T2g(2) and T2g(3) modes on Ti concentration. The most prominent feature is the appearance and increase in the relative intensity of a T2g(3) peak above x = ̃0.2. On the other hand, the Raman peak for the T2g(2) mode gradually diminishes as Ti increases and nearly disappears at x = ̃0.6. Combining the two relative intensities potentially provides a sensitive indicator of Ti content. The technique was applied to study titanomagnetite in grains from Hana Volcanics and melatroctolite from Rhode Island. Keywords: Titanomagnetites, Raman spectroscopy, Fe-Ti oxides, spinel.

Lemelin M.,Hawaii Institute of Geophysics and Planetology | Blair D.M.,Purdue University | Roberts C.E.,State University of New York at Buffalo | Runyon K.D.,Johns Hopkins University | And 2 more authors.
Planetary and Space Science | Year: 2014

Our understanding of the Moon has advanced greatly over the last several decades thanks to analyses of Apollo samples and lunar meteorites, and recent lunar orbital missions. Notably, it is now thought that the lunar poles may be much more enriched in H2O and other volatile chemical species than the equatorial regions sampled during the Apollo missions. The equatorial regions sampled, themselves, contain more H2O than previously thought. A new lunar mission to a polar region is therefore of great interest; it could provide a measure of the sources and processes that deliver volatiles while also evaluating the potential in situ resource utilization value they may have for human exploration. In this study, we determine the optimal sites for studying lunar volatiles by conducting a quantitative GIS-based spatial analysis of multiple relevant datasets. The datasets include the locations of permanently shadowed regions, thermal analyses of the lunar surface, and hydrogen abundances. We provide maps of the lunar surface showing areas of high scientific interest, including five regions near the lunar north pole and seven regions near the lunar south pole that have the highest scientific potential according to rational search criteria. At two of these sites - a region we call the "Intercrater Polar Highlands" (IPH) near the north pole, and Amundsen crater near the south pole - we provide a more detailed assessment of landing sites, sample locations, and exploration strategies best suited for future human or robotic exploration missions. © 2014 Elsevier Ltd.

Loading Hawaii Institute of Geophysics and Planetology collaborators
Loading Hawaii Institute of Geophysics and Planetology collaborators