ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • GEOPHYSICS  (7)
Collection
Keywords
  • 1
    Publication Date: 2013-08-31
    Description: The depths, vertical extents, and lateral extents of magma chambers and their formation are discussed. The depth to the center of a magma chamber is most probably determined by the density structure of the lithosphere; this process is explained. It is commonly assumed that magma chambers grow until the stress on the roof, floor, and side-wall boundaries exceed the strength of the wall rocks. Attempts to grow further lead to dike propagation events which reduce the stresses below the critical values of rock failure. The tensile or compressive failure of the walls is discussed with respect to magma migration. The later growth of magma chambers is accomplished by lateral dike injection into the country rocks. The factors controlling the patterns of growth and cooling of such dikes are briefly mentioned.
    Keywords: GEOPHYSICS
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 579-580
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2014-10-08
    Description: As part of an analysis program to better understand the diversity of volcanic processes on the terrestrial planets, an investigation of the volcanic landforms which exist on the Earth's ocean floor was initiated. In part, this analysis is focused toward gaining a better understanding of submarine volcanic landforms in their own right, but also it is hoped that these features may show similarities to volcanic landforms on Venus, due to the high ambient water (Earth) and atmospheric (Venus) pressures. A series of numerical modelling experiments was performed to investigate the relative importance of such attributes as water pressure and temperature on the eruption process, and to determine the rate of cooling and emplacement of lava flows in the submarine environment. Investigations to date show that the confining water pressure and the buoyancy effects of the surrounding water significantly affect the styles of volcanism on the ocean floor. In the case of Venusian volcanism, confining pressures will not be as great as that found at the ocean's abyssal plains, but nevertheless the general trend toward reducing magma vesiculation will hold true for Venus as well as the ocean floor. Furthermore, other analogs may also be found between submarine volcanism and Venusian activity.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Repts. of Planetary Geol. and Geophys. Program; p 277-279
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2019-01-25
    Description: Analysis of the processes controlling the advance of lava flows shows that, if no other factors intervene, thermal constraints will act to limit the maximum length of a flow being fed at a given volume or mass effusion rate from a vent. These constraints can be characterized through the Gratz number, which takes on a large value at the vent and decreases down flow. Early application of this principle showed that, despite the many subtleties of modes of heat loss from flows, motion apparently ceases when the Gratz number has decreased to a value close to 300. Recent analyses of flow units from the 1983-86 Pu'u 'O'o eruption of Kilauea and of other, more silicic lava flow units confirm this finding.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1527-1528
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2019-01-25
    Description: Perched lava ponds are infrequent but distinctive topographic features formed during some basaltic eruptions. Two such ponds, each approximately 150 m in diameter, formed during the 1968 eruption at Napau Crater and the 1974 eruption of Mauna Ulu, both on Kilauea Volcano, Hawaii. Each one formed where a channelized, high volume flux lava flow encountered a sharp reduction of slope: the flow spread out radially and stalled, forming a well-defined terminal levee enclosing a nearly circular lava pond. We describe a model of how cooling limits the motion of lava spreading radially into a pond and compare this with the case of a channelized flow. The difference in geometry has a major effect, such that the size of a pond is a good indicator of the volume flux of the lava forming it. Lateral spreading on distal shallow slopes is a major factor limiting the lengths of lava flows.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1525-1526
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2019-01-25
    Description: Long-lived eruptions from basaltic volcanoes involving episodic or steady activity indicate that a delicate balance has been struck between the rate of magma cooling in the dike system feeding the vent and the rate of magma supply to the dike system from a reservoir. We describe some key factors, involving the relationships between magma temperature, magma rheology, and dike geometry that control the nature of such eruptions.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1115-1116
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2019-06-27
    Description: Photographic records of 10 vulcanian eruption clouds produced during the 1978 eruption of Fuego Volcano in Guatemala have been analyzed to determine cloud velocity and acceleration at successive stages of expansion. Cloud motion is controlled by air drag (dominant during early, high-speed motion) and buoyancy (dominant during late motion when the cloud is convecting slowly). Cloud densities in the range 0.6 to 1.2 times that of the surrounding atmosphere were obtained by fitting equations of motion for two common cloud shapes (spheres and vertical cylinders) to the observed motions. Analysis of the heat budget of a cloud permits an estimate of cloud temperature and particle weight fraction to be made from the density. Model results suggest that clouds generally reached temperatures within 10 K of that of the surrounding air within 10 seconds of formation and that dense particle weight fractions were less than 2% by this time. The maximum sizes of dense particles supported by motion in the convecting clouds range from 140 to 1700 microns.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 85; May 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-27
    Description: Volcanological observations of explosive eruptions show that previous estimates of pre-explosion gas pressures may be overestimated by an order of magnitude.
    Keywords: GEOPHYSICS
    Type: NASA-CR-157063
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...