Passive lunar seismic experiment
Design of three-axes seismographic system for Apollo lunar landing mission
APOLLO PROJECT↗
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With Swedish geophysicists
Research projects and seismic and gravimetric instrumentation at Swedish university and geophysical observatory
SEISMOLOGY↗
Seismic Holography of Solar Activity
The basic goal of the project was to extend holographic seismic imaging techniques developed under a previous NASA contract, and to incorporate phase diagnostics. Phase-sensitive imaging gives us a powerful probe of local thermal and Doppler perturbations in active region subphotospheres, allowing us to map thermal structure and flows associated with "acoustic moats" and "acoustic glories". These remarkable features were discovered during our work, by applying simple acoustic power holography to active regions. Included in the original project statement was an effort to obtain the first seismic images of active regions on the Sun's far surface.
Lindsey, Charles↗
High-Quality Seismic Observations of Sonic Booms
The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on Earthquake Warning Systems in order to prevent such systems from experiencing false alarms due to sonic booms. The airspace above the Antelope Valley, California includes the High Altitude Supersonic Corridor and the Black Mountain Supersonic Corridor. These corridors are among the few places in the US where supersonic flight is permitted, and sonic booms are commonplace in the Antelope Valley. One result of this project is a rich dataset of high-quality accelerometer records of sonic booms which can shed light on the interaction between these atmospheric phenomena and the solid earth. Nearly 100 sonic booms were recorded with low-noise triaxial MEMS accelerometers recording 1000 samples per second. The sonic booms had peak overpressures ranging up to approximately 10 psf and were recorded in three flight series in 2010 and 2011. Each boom was recorded with up to four accelerometers in various array configurations up to 100 meter baseline lengths, both in the built environment and the free field. All sonic booms were also recorded by nearby microphones. We present the results of the project in terms of the potential for sonic-boom-induced false alarms in Earthquake Warning Systems, and highlight some of the interesting features of the dataset.
Wurman, Gilead↗
New Inquiry into Distribution and Mechanism of Deep Moonquakes with Recently Identified Seismic Events
The objectives of the project were (1) to complete our preceding effort, supported by NASA grant NAGS-1 1619, of searching for deep moonquakes in the far hemisphere of the Moon among the seismic events detected by the Apollo seismic array; and (2) to re-examine the distribution and mechanism of deep moonquakes in the light of the newly identified deep moonquakes. The project was originally planned for completion in three years, of which only the first year, covered by this report, was funded. As a result, we were able to address only the first objective during the period, and the major part of the second objective was left for the future.
Nakamura, Yosio↗
Comment on the letter 'On the influx of small comets into the earth's upper atmosphere. II - Interpretation'
A critical comment is made on the proposal by Frank et al. (1986) that a flux of small comets constantly impacts the earth's atmosphere. It is argued that the interpretation of the 'atmospheric holes' in terms of such an influx is difficult to reconcile with the fact that the lunar seismic network set up during the Apollo project did not detect such an influx. Frank et al. reply that this discrepancy may be traced to the insensitivity of the lunar seismic stations for the detection of the impacts of tenuous, weakly bound comets relative to those of dense, stony meteoroids.
Nakamura, Yosio↗
Acoustic Holography of the Solar Convection Zone with SOHO-MDI Observations
The original grant with the title stated above was NAG5-10984, awarded to the Solar Physics Research Corporation (SPRC) in July, 2001, and was to be a three-year project. The basic theme of the project was the development and application of computational seismic holography for imaging, diagnostics, and monitoring of magnetic anomalies beneath active regions, in the deep solar interior, and on the Sun's far surface. The project was roughly separated into the following five tasks: (1) A holographic survey of active regions. (2) p-Mode absorption diagnostics of magnetic regions. (3) Acoustic modeling of the shallow subphotospheres of active regions and the quiet-Sun supergranulation based on phase-correlation seismic holography. (4) Seismic holography of the deep convection zone. (5) Improvements in holographic imaging of the far surface of the Sun. Following the death of Karen Harvey, President of SPRC, during the first year, the grant was transferred to Northwest Research Associates as NAG5-12901. Substantial but progress had been made on most of the above tasks in the first year under NAG5-10984, but none were completed. This work was continued under NAG5-12901.
Lindsey, Charles↗
A look at Alaskan resources with Landsat data
Landsat data remains a vital tool for the management of resources in Alaska. Utilization of these data by many agencies in Alaska trends toward the solution to operational problems in a wide spectrum of disciplinary applications. Four examples of current applications are reviewed briefly: mapping of coastal sediment plumes, mapping of coastal zone ecosystems, mapping of landform and ground cover for proposed national parks and forests, and evaluation of seismic risks for a proposed hydroelectric project.
Miller, J. M.↗
The Effect of Sonic Booms on Earthquake Warning Systems
Several aerospace companies are designing quiet supersonic business jets for service over the United States. These aircraft have the potential to increase the occurrence of mild sonic booms across the country. This leads to interest among earthquake warning (EQW) developers and the general seismological community in characterizing the effect of sonic booms on seismic sensors in the field, their potential impact on EQW systems, and means of discriminating their signatures from those of earthquakes. The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. (SWS) and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on EQW sensors. The study consists of exposing high-sample-rate (1000 sps) triaxial accelerometers to sonic booms with overpressures ranging from 10 to 600 Pa in the free field and the built environment. The accelerometers record the coupling of the sonic boom to the ground and surrounding structures, while microphones record the acoustic wave above ground near the sensor. Sonic booms are broadband signals with more high-frequency content than earthquakes. Even a 1000 sps accelerometer will produce a significantly aliased record. Thus the observed peak ground velocity is strongly dependent on the sampling rate, and increases as the sampling rate is reduced. At 1000 sps we observe ground velocities that exceed those of P-waves from M L 3 earthquakes at local distances, suggesting that sonic booms are not negligible for EQW applications. We present the results of several experiments conducted under SonicBREWS showing the effects of typical-case low amplitude sonic booms and worst-case high amplitude booms. We show the effects of various sensor placements and sensor array geometries. Finally, we suggest possible avenues for discriminating sonic booms from earthquakes for the purposes of EQW.
Wurman, Gilead↗
A Geophysical Atlas for Interpretation of Satellite-derived Data
A compilation of maps of global geophysical and geological data plotted on a common scale and projection is presented. The maps include satellite gravity, magnetic, seismic, volcanic, tectonic activity, and mantle velocity anomaly data. The Bibliographic references for all maps are included.
Lowman, P. D., Jr.↗
Satellite Geodetic Constraints On Earthquake Processes: Implications of the 1999 Turkish Earthquakes for Fault Mechanics and Seismic Hazards on the San Andreas Fault
Our principal activities during the initial phase of this project include: 1) Continued monitoring of postseismic deformation for the 1999 Izmit and Duzce, Turkey earthquakes from repeated GPS survey measurements and expansion of the Marmara Continuous GPS Network (MAGNET), 2) Establishing three North Anatolian fault crossing profiles (10 sitedprofile) at locations that experienced major surface-fault earthquakes at different times in the past to examine strain accumulation as a function of time in the earthquake cycle (2004), 3) Repeat observations of selected sites in the fault-crossing profiles (2005), 4) Repeat surveys of the Marmara GPS network to continue to monitor postseismic deformation, 5) Refining block models for the Marmara Sea seismic gap area to better understand earthquake hazards in the Greater Istanbul area, 6) Continuing development of models for afterslip and distributed viscoelastic deformation for the earthquake cycle. We are keeping close contact with MIT colleagues (Brad Hager, and Eric Hetland) who are developing models for S. California and for the earthquake cycle in general (Hetland, 2006). In addition, our Turkish partners at the Marmara Research Center have undertaken repeat, micro-gravity measurements at the MAGNET sites and have provided us estimates of gravity change during the period 2003 - 2005.
Reilinger, Robert↗
Deformation of Alaskan Volcanoes, Measured by Satellite Radar Inferometry
The purpose of this project was to determine the suitability of measuring active deformation of volcanoes in Alaska using Interferometric Synthetic Aperture Radar (INSAR) techniques. Work sponsored by this grant supported one graduate student (for almost 2 years) and one postdoc (for several months), and has resulted in two published peer-reviewed papers and a front-page article in EOS. An additional paper is in review and a fourth is in preparation. An additional paper in preparation was based in part on research supported by this grant and in part by a successor grant from NASA's Solid Earth Natural Hazards program. Over the course of this research, we documented measurable uplift of Trident volcano in the Katmai group, conducted a systematic study of the change in phase coherence over time on volcanic surfaces, and measured and modeled the spectacular 1.5 m deflation of Okmok caldera associated with its 1997 eruption. We also generated initial interferograms spanning the 1996 seismic swarm of Akutan volcano; however, during the period covered by this project we were not able to remove topography. That has been done under the subsequent funding and a paper is now in preparation. This report summarizes work done under two separate contracts because both were based on the same proposal to NASA's ADRO (Application Development and Research Opportunity) program. The first year was funded out of a grant from NASA Headquarters and the second and third years out of a grant through Goddard. The work, however, was a continuous three year effort.
Freymueller, Jeff↗
Seismic study of the solar subsurface based on robust time-distance inferences
Progress on this project has been constrained by the unexpected death of my long time collaborator, Peter Nisenson. I worked on several other projects as a collaborator of Pete, who became seriously ill in November 2003. He continued to work as much as his condition allowed him, but his condition worsened, and Pete died on June 21 2004. I ended up a year ago with an expected substantial workload increase. I had no choice but to re-prioritize my efforts, and one other project in which Pete would have taken a substantial role, has in the past year taken an unexpected large fraction of my time.
Korzennik, Sylvain G.↗
Cluster Analysis of Thermal Icequakes Using the Seismometer to Investigate Ice and Ocean Structure (SIIOS): Implications for Ocean World Seismology
Ocean Worlds are of high interest to the planetary community due to the potential habitability of their subsurface oceans. Over the next few decades several missions will be sent to ocean worlds including the Europa Clipper, Dragonfly, and possibly a Europa lander. The Dragonfly and Europa lander missions will carry seismic payloads tasked with detecting and locating seismic sources. The Seismometer to Investigate Ice and Ocean Structure (SIIOS) is a NASA PSTAR funded project that investigates ocean world seismology using terrestrial analogs. The goals of the SIIOS experiment include quantitatively comparing flight-candidate seismometers to traditional instruments, comparing single-station approaches to a small-aperture array, and characterizing the local seismic environment of our field sites. Here we present an analysis of detected local events at our field sites at Gulkana Glacier in Alaska and in Northwest Greenland approximately 80 km North of Qaanaaq, Greenland. Both field sites passively recorded data for about two weeks. We deployed our experiment on Gulkana Glacier in September 2017 and in Greenland in June 2018. At Gulkana there was a nearby USGS weather station which recorded wind data. Temperature data was collected using the MERRA satellite. In Greenland we deployed our own weather station to collect temperature and wind data. Gulkana represents a noisier and more active environment. Temperatures fluctuated around 0°C, allowing for surface runoff to occur during the day. The glacier had several moulins, and during deployment we heard several rockfalls from nearby mountains. In addition to the local environment, Gulkana is located close to an active plate boundary (relative to Greenland). This meant that there were more regional events recorded over two weeks, than in Greenland. Greenland’s local environment was also quieter, and less active. Temperatures remained below freezing. The Greenland ice was much thicker than Gulkana (~850 m versus ~100 m) and our stations were above a subglacial lake. Both conditions can reduce event detections from basal motion. Lastly, we encased our Greenland array in an aluminum vault and buried it beneath the surface unlike our array in Gulkana where the instruments were at the surface and covered with plastic bins. The vault further insulated the array from thermal and atmospheric events.
Marusiak, A. G.↗
Mineral resources, geological structure, and landform surveys
Diagnostic ERTS imagery has been used to pinpoint surface conditions associated with known mining districts. These include enhancements which depict hitherto unrecognized surface alteration and allow analysis of ore-controlling fractures distribution in a regional context. ERTS has likewise provided observational data containing previously unrecognized surface anomalies in large oil-producing basins which correlate closely with known oil fields. These observational data offer promise of providing new and powerful techniques for oil exploration, especially if further work using more sophisticated enhancement-processing proves capable of emphasizing the anomalies. ERTS is showing a better-than-anticipated potential for producing accurate small-scale (large-area) geologic maps, often containing details that were previously not recorded on similar regional maps. The maps produced from ERTS imagery can be prepared more effectively than previously possible, mainly because of the synoptic, multispectral, and repetitive character of ERTS data. ERTS has also provided extensive information on possible geologic hazards. Many new fractures have been identified in several regions of the Pacific Coast seismic belt that have histories of recent earthquakes. This has obvious implications for engineering projects such as dams, aqueducts, and transportation routes. In the mid-continent area, ERTS data have been used to predict zones of rooffall danger in a working coal mine from newly discovered lineations (probably fractures) used as indicators of hazards.
Short, N. M.↗
Tectonic structure of Alaska as evidenced by ERTS imagery and ongoing seismicity
The author has identified the following significant results. At least three seismically active faults were identified which had not been previously mapped. One of these passes near the proposed site of a hydroelectric project on the Susitna River. Evidence of the state's past deformational history was obtained, indicating that right lateral offset has occurred sequentially from the northern part of the state to the southern. An apparent fault passes near Fairbanks, and is presumably the source of much seismic activity in the area.
Gedney, L. D.↗
Time-dependent gravity in Southern California, May 1974 to April 1979
The Southern California gravity survey, begun in May 1974 to obtain high spatial and temporal density gravity measurements to be coordinated with long-baseline three dimensional geodetic measurements of the Astronomical Radio Interferometric Earth Surveying project, is presented. Gravity data was obtained from 28 stations located in and near the seismically active San Gabriel section of the Southern California Transverse Ranges and adjoining San Andreas Fault at intervals of one to two months using gravity meters relative to a base station standard meter. A single-reading standard deviation of 11 microGal is obtained which leads to a relative deviation of 16 microGal between stations, with data averaging reducing the standard error to 2 to 3 microGal. The largest gravity variations observed are found to correlate with nearby well water variations and smoothed rainfall levels, indicating the importance of ground water variations to gravity measurements. The largest earthquake to occur during the survey, which extended to April, 1979, is found to be accompanied in the station closest to the earthquake by the largest measured gravity changes that cannot be related to factors other than tectonic distortion.
Whitcomb, J. H.↗
GeoSAR: A Radar Based Terrain Mapping Project
GeoSAR is a project to develop a commercial airborne, radar-based, terrain mapping system utilizing technology originally developed by NASA and ARPA for commercial and defense applications. GeoSAR has three primary goals: (1) validation of radar terrain mapping technology developed by NASA/JPL and ARPA. (2) application of this technology to seismic hazards and environmental mapping for the Department of Commerce and other governmental agencies, and (3) demonstration of commercial marketability via end-user projects using real world problems and applications.
Yoha, Robert↗