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NASA NTRS1982

Sources of lunar magnetic anomalies and their bulk directions of magnetization - Additional evidence from Apollo orbital data

A relatively high-amplitude magnetic anomaly directly detected with the Apollo 15 subsatellite magnetometer and centered near the crater Gerasimovich on the southeastern lunar far side is found to correlate with the location of a conspicuous Reiner Gamma-type swirl marking visible on a Zond 8 photograph. Examinations of available direct and indirect orbital magnetics measurements demonstrate that most strong anomalies occur in areas where morphologically similar markings are concentrated. Even though photogeologic studies indicate an impact-related origin for the swirls, both the swirls and their associated strong anomalies tend to exist preferentially in or near areas that have been seismically modified. Modeling of improved vector magnetic anomaly maps is used to infer 28 independent bulk directions of magnetization for relatively strong and isolated lunar magnetic anomaly sources.

Hood, L. L.↗

NASA NTRS1995

GPS detection of ionospheric perturbations following the January 17, 1994, northridge earthquake

Sources such as atmospheric or buried explosions and shallow earthquakes producing strong vertical ground displacements produce pressure waves that propagate at infrasonic speeds in the atmosphere. At ionospheric altitudes low frequency acoustic waves are coupled to ionispheric gravity waves and induce variations in the ionoispheric electron density. Global Positioning System (GPS) data recorded in Southern California were used to compute ionospheric electron content time series for several days preceding and following the January 17, 1994, M(sub w) = 6.7 Northridge earthquake. An anomalous signal beginning several minutes after the earthquake with time delays that increase with distance from the epicenter was observed. The signal frequency and phase velocity are consistent with results from numerical models of atmospheric-ionospheric acoustic-gravity waves excited by seismic sources as well as previous electromagnetic sounding results. It is believed that these perturbations are caused by the ionospheric response to the strong ground displacement associated with the Northridge earthquake.

Calais, Eric↗

NASA NTRS2005

Crustal Deformation and the Seismic Cycle Across the Kodiak Islands, Alaska

The Kodiak Islands are located approximately 120 to 250 km from the Alaska-Aleutian Trench - and are within the southern extent of the 1964 Prince William Sound (M(sub w) = 9.2) earthquake rupture zone. Here we report new campaign GPS results (1993-2001) from northern Kodiak Island. The rate and orientation of the horizontal velocities, relative to a fixed North America, range from 25.3 plus or minus 1.4 mm/yr at N32.9 deg. W plus or minus 2.5 to 8.5 plus or minus 1.0 mm/yr at N59.7 deg. W plus or minus 6.5 deg. In addition to the northern Kodiak data, we analyzed data from three southern Kodiak Island stations. The inland stations from both the northern and southern networks indicate a counterclockwise rotation of the velocity vectors. These results are consistent with the hypothesis that the difference between the Pacific-North American plate motion and the orientation of the down going slab would lead to 4-8 mm/yr of left-lateral slip above the unlocked, down-dip portion of the main thrust zone. The northern and southern Kodiak geodetic data are consistent with a model that includes the viscoelastic response to (1) a downgoing Pacific plate interface that is locked at shallow depths, (2) local coseismic slip in the 1964 earthquake, and (3) interseismic creep down dip from the seismogenic zone. Based on the pre-1964 and post-1944 earthquake history, as well as the pattern of interseismic earthquakes across the plate boundary zone, we hypothesize that in southern Kodiak some strain is released in moderate to large earthquakes between the occurrences of great earthquakes like the 1964 event.

Sauber, Jeanne↗

NASA NTRS1985

Geometric and chronologic evolution of the Verde and Payson Basins of Central Arizona and possible relationships to detachment faulting

The Transition Zone of Arizona and the structural basins therein have been poorly understood features from a structural standpoint. This is true both of their overall geometry as well as their formation. Yet these basins have developed within the last 13 million years and thus represent perhaps the most recent phase of development related to the extensional tectonics of the Basin and Range province. Recent work (Smith, 1984; Vance, 1983) as well as some older studies (Anderson and Creasy, 1985; Pedersen and Royce, 1970) provide data on the geometry of the Verde and Payson basins which can be used to constrain some hypotheses related to the development of these basins. The work of Cloos (1868), Anderson et. al. (1983), Wernicke and Burchfiel (1982) and Davis et. al. (l980) suggest a spatial and chronologic relation exists between planar high angle normal faults and low angle detachment faults. Perhaps one of the clearest examples from the Basin and Range area appears to be from seismic reflection profiles of the Sevier Desert Basin area of Utah (Fig. 1). These profiles suggest the existence fault-controlled extension basin development above it. Faults that appear either listric or planar intersect it from above.

Brumbaugh, D. S.↗

NASA NTRS1987

Consequences of experimental transient rheology

Recent analyses of transient creep data for lower crustal and upper mantle substances are used to constrain the viscosity contrast across the 670 km discontinuity, and a 4-layer earth model in which both upper and lower mantles are described by a Burgers body rheology is assumed. Results indicate that the previously inferred viscosity variations would be reduced by a factor of ten using the new transient models. This result is in agreement with a revised viscosity estimate based on long-wavelength geoid anomalies and seismic tomography. Time-dependent perturbations to the gravity field from recent ice movements are shown to be significant.

Sabadini, Roberto↗

NASA NTRS2022

Insights from the Topographic Characteristics of a Large Global Catalog of Rainfall-Induced Landslide Event Inventories

Landslides are a key hazard in high-relief areas around the world and pose a risk to population and infrastructure. It is important to understand where landslides are likely to occur in the landscape to inform local analyses of exposure and potential impacts. Large triggering events such as earthquakes or major rain storms often cause hundreds or thousands of landslides, and mapping the landslide populations generated by these events can provide extensive datasets of landslide locations. Previous work has explored the characteristic locations of landslides triggered by seismic shaking, but rainfall induced landslides are likely to occur in different parts of a given landscape when compared to seismically induced failures. Here we show measurements of a range of topographic parameters associated with rainfall-induced landslides inventories, including a number of previously unpublished inventories which we also present here. We find that average upstream angle and compound topographic index are strong predictors of landslide scar location, while local relief and topographic position index provide a stronger sense of where landslide material may end up (and thus where hazard may be highest). By providing a large compilation of inventory data for open use by the landslide community, we suggest that this work could be useful for other regional and global landslide modelling studies and local calibration of landslide susceptibility assessment, as well as hazard mitigation studies.

Robert Emberson↗

NASA NTRS2001

Seismic Study of the Dynamics of the Solar Subsurface from SoHO Observations

In collaboration with Dr. Baudin, we have developed and refined the new observational methodology for local helioseismology known as time-distance analysis. Global helioseismology study the solar oscillations as a superposition of resonant modes, whose properties (mode frequencies) reflect the global structure of the sun (sound speed stratification, rotation rate, etc). In contrast, local helioseismology look at the solar oscillations as wave packets whose propagation will be affected by perturbations of the media sampled. These local perturbations (sound speed or velocity flows) will modify the propagation time, that in turn can be used as a diagnostic tool for a given region. From a data reduction perspective, the processing of solar dopplergrams that result in time-distance maps, i.e. propagation times as a function of distance between bounces at the surface, is radically different from the methodology used for global mode analysis. We have, in a first step, further develop the programs needed to carry out such analysis. We have then applied them to NMI data set, and explore the trade-off between various averaging and filtering approaches - steps required to improve the signal-to-noise ratio of correlation maps - and the resulting stability and precision of the fitted propagation times. While excessive averaging (whether over space, propagation distance, or time) will reduce the diagnostic potential of the method, insufficient averaging lead to unstable fits, or uncertainties so large as to hide the information we seek. In a second phase, we have developed the analysis methodology required to infer local properties from perturbation in time propagation. Namely, we have developed time-distance inversion techniques, with an emphasis on inferences of velocity flows from time anomalies. Note also that during the period covered by this grant, all the investigators on this proposal (i.e., Drs. Baudin, Eff-Darwich, Korzennik, and Noyes) took part in the organization of the SOHO 6 /GONG 99 Workshop: Structure and Dynamics of the Interior of the Sun and Sunlike Stars, held on June 1-4 1999 at the Boston Park Plaza Hotel in Boston, Massachusetts, USA. it was very well attended by more than 160 participants from 26 countries from all over the world. The proceedings were published in two volumes as ESA SP-418, with Sessions I-III in Volume 1, and Sessions IV-VI in Volume 2 (1,000 pages in total). The complete contents are also included in digital form on a CD-ROM included with Volume 1. This CD-ROM also contains additional multi-media material that complements some of the contributions.

Korzennik, Sylvain G.↗

NASA NTRS2001

Seismic Study of the Solar Interior: Inferences from SOI/MDI Observations During Solar Activity

We have continued in collaboration with Dr. Eff-Darwich (University of La Laguna, Tenerife, Spain) the study of the structure, asphericity and dynamics of the solar interior from p-mode frequencies and frequency splittings. In March 2001, Dr. Eff-Darwich came for 3 weeks visit to CfA. During this visit we completed our work on the inversion of the internal solar rotation rate, and submitted a paper describing this work to the Astrophysical Journal. This paper has been recently revised in response to the referee comments and I expect that it will be accepted for publication very soon. We also have analyzed helioseismic data looking for temporal variations of the solar stratification near the base of the convection zone. We have expanded on the initial work that was presented at the SOHO-10/GONG-2000 meeting (October 2000, Tenerife), and are in the process of writing this up. Substantial progress towards the characterization of high-degree p-modes has been achieved. Indeed, in collaboration Dr. Rabello-Soares (Stanford University), we have gained a clear conceptual understanding of the various elements that affect the leakage matrix of the SOI/MDI instrument. This was presented in an invited talk at the SOHO-10/GONG-2000 meeting (October 2000, Tenerife). Once we will have successfully migrated from a qualitative to a quantitative assessment of these effects, we should be able to generate high-degree p-modes frequencies so crucial in the diagnostic of the layers just below solar surface.

Korzennik, Sylvain G.↗

NASA NTRS1985

Constraints on short-term mantle rheology from the J2 observation and the dispersion of the 18.6 y tidal Love number

Information derived from data recently acquired from the LAGEOS satellite is used to place some constraints on the rheological parameters of short-term mantle rheology. The validity of Lambeck and Nakiboglu's (1983) rheological model is assessed by formally developing an expression for the transformed shear modulus using a truncated retardation spectrum. This analytical formula is used to show that the parameters of the above mentioned model are not consistent at all with the amount of anelastic dispersion expected in the Chandler wobble and with the attenuation of seismic normal modes. The feasibility of a standard linear solid (SLS) rheology operating over intermediate timescales between 1 and 100 yr is investigated to determine whether the tidal dispersion at 18.6 yr can be explained by this model. An attempt is made to place some constraints on the parameters of the SLS model and the nature of short-term mantle rheology for timescales of less than 100 yr is discussed.

Sabadini, R.↗

NASA NTRS1974

Seismic scattering and shallow structure of the moon in Oceanus Procellarum

Scattering in a high-Q medium has been the best hypothesis to date for explaining the observation of a long, reverberating train of waves in lunar seismographs. To test this hypothesis qualitatively, two experiments were devised which simulated this scattering and reproduced actual lunar seismographs. Pulses were propagated across a plate with grooves cut half-way through, and then were propagated along the edge of a plate with holes drilled within a skin depth of the edge. The seismographs of near impacts and moonquakes recorded by the Apollo 12 station in two frequency bands were studied. The impacts were those of S4B Saturn boosters and LM ascent stages. Interpretation of these data suggests the existence of a scattering layer 25 km thick with a Q of 5000. The density of the scatterers decreases with depth, suggesting that they are associated with cratering, or that they consist of cracks which anneal with depth.

Dainty, A. M.↗

NASA NTRS1977

A search for gaseous emissions from the moon

A study of 19 months of data shows that relative variations in the dayside lunar ionosphere are predictable from solar-wind flux and solar extreme-ultraviolet variations. Discrepancies in the absolute magnitudes exist, however. One significant discrepancy in the predicted and observed ion-flux magnitudes probably arises from sputtered surface gases during and following an extended period of anomalously high solar-wind flux. A second minor enhancement of the observed flux over the predicted flux may be due to endogenous lunar gas associated with an interval of high lunar seismic activity. However, considerable restraint is necessary in this interpretation since the enhancement is not strong and the interval follows within a few months after the Apollo 17 mission.

Freeman, J. W.↗

NASA NTRS2001

Atmospheric Excitation of Planetary Normal Modes

The objectives of this study were to: (1) understand the phenomenon of continuous free oscillations of the Earth and (2) examine the idea of using this phenomenon for planetary seismology. We first describe the results on (1) and present our evaluations of the idea (2) in the final section. In 1997, after almost forty years since the initial attempt by Benioff et al, continuous free oscillations of the Earth were discovered. Spheroidal fundamental modes between 2 and 7 millihertz are excited continuously with acceleration amplitudes of about 0.3-0.5 nanogals. The signal is now commonly found in virtually all data recorded by STS-1 type broadband seismometers at quiet sites. Seasonal variation in amplitude and the existence of two coupled modes between the atmosphere and the solid Earth support that these oscillations are excited by the atmosphere. Stochastic excitation due to atmospheric turbulence is a favored mechanism, providing a good match between theory and data. The atmosphere has ample energy to support this theory because excitation of these modes require only 500-10000 W whereas the atmosphere contains about 117 W of kinetic energy. An application of this phenomenon includes planetary seismology, because other planets may be oscillating due to atmospheric excitation. The interior structure of planets could be learned by determining the eigenfrequencies in the continuous free oscillations. It is especially attractive to pursue this idea for tectonically quiet planets, since quakes may be too infrequent to be recorded by seismic instruments.

Tanimoto, Toshiro↗

NASA NTRS1977

Terrestrial environment (Climatic) criteria guidelines for use in aerospace vehicle development, 1977 revision

Guidelines are provided on terrestrial environment data specifically applicable for NASA aerospace vehicles and associated equipment development. Information is included on the general distribution of natural environment extremes in the conterminous United States that may be needed to specify design criteria in the transportation of space vehicle subsystems and components. Atmospheric attenuation was investigated since certain earth orbital experiment missions are influenced by the earth's atmosphere. A summary of climatic extremes for worldwide operational needs is also included. The latest available information on probable climatic extremes is presented with information on atmospheric chemistry, seismic criteria, and on a mathematical model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth. Cloud phenomena are also considered.

Kaufman, J. W.↗

NASA NTRS1993

Manson impact structure, Iowa: First geochemical results for drill core M-1

The Manson Impact Structure is a large complex impact crater centered ca. S km north of the town of Manson, Iowa. It is the largest intact impact structure recognized in the United States (35 km in diameter). Its Ar-40/Ar-39 age is indistinguishable from that of the Cretaceous-Tertiary (K-T) boundary. The Manson structure may be one element of the events at the K-T boundary. The crater is completely covered by Quaternary glacial sedimentary deposits that are normally underlain by Cretaceous clastic sediments and flat-lying carbonate sediments of Phanerozoic age, as well as Proterozoic red clastic, metamorphic, volcanic, and plutonic rock sequences. The study of a reflection seismic profile, provided by Amoco, was critical in interpreting the structure. In the 35 km diameter zone that marks the extension of the crater the normal rock sequence is disturbed due to the impact, and at the center of the structure granitic basement rocks are present that have been uplifted from about 4 km depth. Our studies consist of detailed petrological and geochemical characterization of all cores, with emphasis on a detailed description of all rock types found in the core samples and their relationship to target rocks. Geochemical data on samples from the Manson M-1 core are presented.

Koeberl, Christian↗

NASA NTRS2004

Cooperative Lander-Surface/Aerial Microflyer Missions for Mars Exploration

Concepts are being investigated for exploratory missions to Mars based on Bioinspired Engineering of Exploration Systems (BEES), which is a guiding principle of this effort to develop biomorphic explorers. The novelty lies in the use of a robust telecom architecture for mission data return, utilizing multiple local relays (including the lander itself as a local relay and the explorers in the dual role of a local relay) to enable ranges ~10 to 1,000 km and downlink of color imagery. As illustrated in Figure 1, multiple microflyers that can be both surface or aerially launched are envisioned in shepherding, metamorphic, and imaging roles. These microflyers imbibe key bio-inspired principles in their flight control, navigation, and visual search operations. Honey-bee inspired algorithms utilizing visual cues to perform autonomous navigation operations such as terrain following will be utilized. The instrument suite will consist of a panoramic imager and polarization imager specifically optimized to detect ice and water. For microflyers, particularly at small sizes, bio-inspired solutions appear to offer better alternate solutions than conventional engineered approaches. This investigation addresses a wide range of interrelated issues, including desired scientific data, sizes, rates, and communication ranges that can be accomplished in alternative mission scenarios. The mission illustrated in Figure 1 offers the most robust telecom architecture and the longest range for exploration with two landers being available as main local relays in addition to an ephemeral aerial probe local relay. The shepherding or metamorphic plane are in their dual role as local relays and image data collection/storage nodes. Appropriate placement of the landing site for the scout lander with respect to the main mission lander can allow coverage of extremely large ranges and enable exhaustive survey of the area of interest. In particular, this mission could help with the path planning and risk mitigation in the traverse of the long-distance surface explorer/rover. The basic requirements of design and operation of BEES to implement the scenarios are discussed. Terrestrial applications of such concepts include distributed aerial/surface measurements of meteorological events, i.e., storm watch, seismic monitoring, reconnaissance, biological chemical sensing, search and rescue, surveillance, autonomous security/ protection agents, and/or delivery and lateral distribution of agents (sensors, surface/subsurface crawlers, clean-up agents). Figure 2 illustrates an Earth demonstration that is in development, and its implementation will illustrate the value of these biomorphic mission concepts.

Thakoor, Sarita↗

NASA NTRS1994

Horizontal crustal motion in the central and eastern Mediterranean inferred from Satellite Laser Ranging measurements

Four campaigns to acquire Satellite Laser Ranging (SLR) measurements at sites in the Mediterranean region have been completed. These measurements to the LAGEOS satellite, made largely by mobile systems, cover a time span beginning in November 1985 and ending in June 1993. The range data from 18 sites in the central and eastern Mediterranean have been simultaneously analyzed with data acquired by the remainder of the global laser tracking network. Estimates of horizontal motion were placed into a regional, northern Europe-fixed, kinematic reference frame. Uncertainties are on the order of 5 mm/yr for sites having at least four occupations by mobile systems and approach 1 mm/yr for permanently located sites with long histories of tracking. The resulting relative motion between sites in the Aegean exhibit characteristics of broadly distributed pattern of radial extension, but at rates that are about 50% larger than those implied from studies of seismic strain rates based on seismicity of magnitude 6 or greater or across the region. The motion estimated for sites in Turkey exhibit velocity components associated with the westward motion of the Anatolian Block relative to Eurasia. These results provide a present-day 'snapshot' of ongoing deformational processes as experienced by the locations occupied by SLR systems.

Smith, David E.↗

NASA NTRS2019

The State of Remote Sensing Capabilities of Cascading Hazards over High Mountain Asia

Cascading hazard processes refer to a primary trigger such as heavy rainfall, seismic activity, or snow melt, followed by a chain or web of consequences that can cause subsequent hazards influenced by a complex array of preconditions and vulnerabilities. These interact in multiple ways and can have tremendous impacts on populations proximate to or downstream of these initial triggers. High Mountain Asia (HMA) is extremely vulnerable to cascading hazard processes given the tectonic, geomorphologic, and climatic setting of the region, particularly as it relates to glacial lakes. Given the limitations of in situ surveys in steep and often inaccessible terrain, remote sensing data are a valuable resource for better understanding and quantifying these processes. The present work provides a survey of cascading hazard processes impacting HMA and how these can be characterized using remote sensing sources. We discuss how remote sensing products can be used to address these process chains, citing several examples of cascading hazard scenarios across HMA. This work also provides a perspective on the current gaps and challenges, community needs, and view forward towards improved characterization of evolving hazards and risk across HMA.

Glacial lake outburst floods↗

NASA NTRS1989

1960 Chile - New estimate of polar motion excitation

A recent reanalysis of the International Latitude Serivce (ILS) polar motion data-day has been processed using Kalman filtering techniques to generate the polar motion excitation function over the time-span from 1960 to 1965. The resulting excitation function has been examined for the effects of 1960 Chile in an attempt to determine experimentally how large earthquake affect polar motion. The resulting upper bound of about 75 x 10 to the 22nd N-m for a 10-deg dip (about 36 x 10 to the 22nd N-m for 20-deg dip) is consistent with results obtained from previous seismic studies, including a recent normal mode excitation result. Following future great earthquakes, monitoring of polar motion by space-based techniques such as VLBI should continue at high temporal resolution for several weeks in order to directly measure the rheological parameters of the upper mantle.

Slade, M. A.↗