GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    acoustic emission due to water infusion into loaded sample as a possible model of swarm seismicity (2007)
    Details
    Publication Date: 2017-04-04
    Description: see Abstract Volume
    Description: Istituto Nazionale di Geofisica e Vulcanologia, Italy (INGV) Centre National de la Recherche Scientifique (CNRS) ExxonMobil Upstream Research Company
    Description: Unpublished
    Description: Erice, Italy
    Description: open
    Keywords: rock physics, geomechanics, thermo-hydro-mechanical coupling, natural hazards ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    An integrated study of physical precursors of failure in relation to earthquake prediction, using large scale rock blocks (2006)
    Details
    Publication Date: 2019-11-04
    Description: This paper is multi-analysis approach to rock failure using metric size rock samples. The use of large-scale models permits simulation of the seismic process (including internal rupture on several scales) and utilization of a dense network for observation of the spatial variations of several physical parameters. The experiments were performed both on solid rock blocks and on concrete blocks with artificial defects, which enabled simulation of internal shear fracture. The number of various precursors appears to rise up to failure, all of them clearly manifest at the stage of a rapid drop in the applied stress (unstable deformation). The experiment suggests that rocks under strain and prior to failure must be characterized by a heterogeneous field of strains. This means that the strain is distributed mosaically, dilatancy does not generate uniformly and areas where it occurs are likely to be structurally mosaic themselves. To reinforce the prediction of micro- and macrofailure, we have realized simultaneous processing of the obtained data, using sophisticated multidimensional orthogonal functions to represent the different precursors. The possibility to identify the early stages of microfailures and to predict the macrofailure by means of statistical complex parameters derived from data on local deformations, acoustic emissions, elastic waves velocities, electric resistivity and self electric potentials is shown. Despite a considerable dissimilarity in mechanical properties of granite basalt and concrete, the complex parameter proves morphologically identical. Parameter S1 reveals exponential rise up to failure in all cases, and parameter S2 is bay-shaped in form, which makes it more promising in terms of prognosis.
    Description: JCR Journal
    Description: open
    Keywords: precursors ; simulation ; failure ; complex parameter ; prediction ; earthquake ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 5010385 bytes
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    Electronic Resource
    Electronic Resource
    Absorption of strain waves in porous media at seismic frequencies (1996)
    Springer
    Pure and applied geophysics 147 (1996), S. 25-55 
    Details
    ISSN: 1420-9136
    Keywords: Dissipation ; strain waves ; poroelasticity ; surface energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An understanding of strain wave propagation in fluid containing porous rocks is important in reservoir geophysics and in the monitoring in underground water in the vicinity of nuclear and toxic waste sites, earthquake prediction, etc. Both experimental and theoretical research are far from providing a complete explanation of dissipation mechanisms, especially the observation of an unexpectedly strong dependence of attenuationQ −1 on the chemistry of the solid and liquid phase involved. Traditional theories of proelasticity do not take these effects into account. In this paper the bulk of existing experimental data and theoretical models is reviewed briefly in order to elecidate the effect of environmental factors on the attenuation of seismic waves. Low fluid concentrations are emphasized. Thermodynamical analysis shows that changes in surface energy caused by weak mechanical disturbances can explain observed values of attenuation in real rocks. Experimental dissipation isotherms are interpreted in terms of monolayered surface adsorption of liquid films as described by Langmuir's equation. In order to describe surface dissipation in consolidated rocks, a surface tension term is added to the pore pressure term in the O'Connell-Budiansky proelastic equation for effective moduli of porous and fractured rocks. Theoretical calculations by this modified model, using reasonable values for elastic parameters, surface energy, crack density and their geometry, lead to results which qualitatively agree with experimental data obtained at low fluid contents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876435
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Simulation of triggered earthquakes in the laboratory (1996)
    Springer
    Pure and applied geophysics 147 (1996), S. 345-355 
    Details
    ISSN: 1420-9136
    Keywords: Stick-slip ; rock ; instability ; model ; earthquake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The experiments were conducted for the study of stick-slip at the contact between two granite blocks. Three cases were studied under the following conditions: 1) the increase of load at a constant rate; 2) the additional application of sinusoidal oscillations in the frequency range from 1 to 30 Hz; 3) subjection to the impulse in the kilohertz frequency range. The imposition of sinusoidal oscillations with the amplitude of 15% of the maximal load caused the reduction of time by 10% for the discussed in terms of durability. The high frequency impulse influence increased this effect and also caused essential changes in the amplitude of elastic oscillations generating during the stick-slip. The trigger phenomena should be integrated in prediction models of the time and magnitude of earthquakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877487
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The spatial and temporal changes inV p /V s before strong earthquakes in Kamchatka (1977)
    Springer
    Pure and applied geophysics 115 (1977), S. 1047-1060 
    Details
    ISSN: 1420-9136
    Keywords: Earthquake ; Velocity ; Prediction ; Epicenter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A method was developed to obtain from a signal station the spatial and temporal distribution ofV p /V s ratios before earthquakes of magnitude〉6. It was shown thatV p /V s values strongly depend upon the relative positions of the stations, the future large earthquake and the foci of the smaller earthquakes used forV p /V s determination. The appearance of a zone of anomalousV p /V s values with linear dimensions of the order of 100 km was noted at least 4 years before a deep earthquake of magnitude 7. Similar size anomalous zones were detected one year before some magnitude 6 earthquakes. V p /V s values decreased by a small but distinct amount during this time. Additionally, local short term minima inV p /V s ratios were observed some months before the major event. The epicenters of the large earthquakes were located within the 100 km size zone where the gradients of theV p /V s field were largest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00881226
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    An experimental study of triggered stick-slip (1993)
    Springer
    Pure and applied geophysics 140 (1993), S. 79-94 
    Details
    ISSN: 1420-9136
    Keywords: Stick-slip ; rock friction ; instability ; precursor ; earthquake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Stick-slips have been studied in the laboratory on granite, labrodorite and sandstone samples of two different sizes. Different roughness was achieved on the sawcut surfaces by finishing them with different grinding compounds ranging from grit 40 to grit 1000. Stick-slips occurred as a result of 1) slowly increasing the shear and normal stresses, 2) superimposing a sinusoidal stress modulation (0.1 and 10 Hz) on the slowly increasing stresses, 3) triggering by a stress impulse when the shear stress was well below the levels where stick-slips occurred without the impulse, and 4) foreshocks. Stick-slips triggered by impulses or foreshocks occurred “long” after the beginning of the triggering events, i.e., long in comparison with elastic wave travel times through the sample. All triggered events were very rich in high frequencies (corner frequency of ∼100 kHz). The untriggered stick-slips did not contain much energy at the high frequencies (corner frequency of ∼10 kHz). The dynamic friction coefficients for the triggered stick-slips were smaller than for the untriggered events. The “long” delay between the onset of the trigger and the stick-slip, and the high frequencies may be a consequence of corrosion of asperities. The ultimate triggering and the rate of corrosion are likely related to the interplay of the normal and shear stresses as they load and unload the fault surface. The consistent shape of the high frequency spectra is probably due to sample resonances which are excited rather than being characteristic of the details of the stick-slips. If these laboratory observations are directly applicable to earthquake seismology, the spectra of earthquakes which were triggered by other earthquakes should be anomalously rich in high frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876872
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The study of barrier fracture in relation to earthquake and rockburst prediction (1986)
    Springer
    Pure and applied geophysics 124 (1986), S. 811-824 
    Details
    ISSN: 1420-9136
    Keywords: Earthquake modelling ; fracturing process ; precursors of failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract One of the simplest models of earthquakes and rockbursts was studied in laboratory conditions in which the fracture was initiated in a barrier between two preexisting faults. The treated models were built of concrete; during the construction of the models, the stress concentrators were inserted inside the models. This arrangement enabled the shear displacement to occur during uniaxial loading of the model. The tests were made on the series of models, the sizes of which were mutually varying more than one order. In the process of the barrier fracture propagation, the following were investigated: the time and space changes of local deformations as well as the acoustic emission, velocities and amplitudes of elastic waves, electrical conductivity and proper electro-induction. The process of barrier fracturing can be understood in three fundamental stages. In the course of the first stage, the density of small tensile cracks increases considerably, while the volume in which they exist is gradually enlarged. In the second stage, as the result, of these cracks coupling, longer shear cracks are created. During the coupling, due to the development of numerous regions of unstable deformation, the zones of nonequal rigidity arise in the treated medium, distributed within it in a mosaic-like pattern. In the third stage, the main fracture is prepared and formed with simultaneous unloading of the surrounding medium. The process of crack forming is gradually localized into a more narrow zone. The second and third stages of fracture forming are reflected in variations of all the above-mentioned physical parameters which are therefore identified as the precursors of the main fracture. By means of the series of precursors it is possible to find the reliable prediction of a barrier fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879612
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Unstable steam-water convection as possible trigger to earthquakes (1995)
    Springer
    Pure and applied geophysics 145 (1995), S. 139-147 
    Details
    ISSN: 1420-9136
    Keywords: Convection ; triggered earthquakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Convection occurs when two water reservoirs, the overlying and the underlying, are connected by a narrow channel and the fluid in the lower reservoir is heated to the stage of phase transition into steam. The laboratory study of the properties of unstable steam-water convection showed that under favourabieP-T conditions the convection can be the triggering mechanism of seismicity. This type of convection causes a sudden fall of pressure in the lower reservoir and in the connecting channel, the impulsive mechanical disturbances, and cyclicity. The point of initiation of this phenomenon can be located at a depth of 5–7 km from the earth's surface with subsequent propagation of the process of instability to larger and smaller depths. This model of the natural terrestrial conditions can account for the earthquake cyclicity in the same focal zones, the rise of temperature and of the level of ground waters during earthquakes, the enhancement of seismicity while filling the water storage basins, the effect of “floating up” of hypocenters of aftershocks and the greater intervals between them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879489
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Two models for earthquake forerunners (1975)
    Springer
    Pure and applied geophysics 113 (1975), S. 169-181 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Similar precursory phenomena have been observed before earthquakes in the United States, the Soviet Union, Japan, and China. Two quite different physical models are used to explain these phenomena. According to a model developed by US seismologists, the so-called dilatancy diffusion model, the earthquake occurs near maximum stress, following a period of dilatant crack expansion. Diffusion of water in and out of the dilatant volume is required to explain the recovery of seismic velocity before the earthquake. According to a model developed by Soviet scientists growth of cracks is also involved but diffusion of water in and out of the focal region is not required. With this model, the earthquake is assumed to occur during a period of falling stress and recovery of velocity here is due to crack closure as stress relaxes. In general, the dilatancy diffusion model gives a peaked precursor form, whereas the dry model gives a bay form, in which recovery is well under way before the earthquake. A number of field observations should help to distinguish between the two models: study of post-earthquake recovery, time variation of stress and pore pressure in the focal region, the occurrence of pre-existing faults, and any changes in direction of precursory phenomena during the anomalous period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01592908
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Application of electric method to the tentative short-term forecast of Kamchatka earthquakes (1975)
    Springer
    Pure and applied geophysics 113 (1975), S. 229-235 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Tentative forecasts of strong earthquakes on Kamchatka have been carried out continuously since 1972 with scientific purpose. Three methods are being used: electric, ratioV p /V s and seismostatistical. The main scientific result of the two-year study is the statement that it is possible to predict earthquakes of magnitude ≥5.5 some days in advance; eight earthquakes had been predicted from a total number of twelve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01592913
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...