The relationship between degassing and ground deformation at Soufriere Hills Volcano, Montserrat     

I. M. Watson  C. Oppenheimer  B. Voight  P. W. Francis  A. Clarke  J. Stix  A. Miller  D. M. Pyle  M. R. Burton  S. R. Young  G. Norton  S. Loughlin  B. Darroux  MVO Staff   《Journal of Volcanology and Geothermal Research》2000,98(1-4)

We examine the correlations between SO₂ emission rate, seismicity and ground deformation in the month prior to the 25 June 1997 dome collapse of the Soufriere Hills Volcano, Montserrat. During this period, the volcano exhibited a pattern of cyclic inflation and deflation with an 8–14 h period. We find that SO₂ emission rates, measured by COSPEC, correlate with the amplitude of these tilt cycles, and that higher rates of SO₂ emission were associated with stronger ground deformation and enhanced hybrid seismicity. Within tilt cycles, degassing peaks coincide with maximum deformation gradients. Increases in the amount of gas in the magma conduit feeding the dome, probably due to increases in volatile content of ascending magma volume can account for the observed increases in tilt amplitude, hybrid seismicity and SO₂ emission rate.  相似文献   

A simple model for H₂ line profiles in bow shocks     

A. S. B. Schultz  M. G. Burton  P. W. J. L. Brand 《Monthly notices of the Royal Astronomical Society》2005,358(4):1195-1214

We present a model for empirically reproducing line profiles of molecular hydrogen emission in bow shocks. The model takes into account bow velocity, dissociation limit, a cooling function, viewing angle, bow shape and a limited form of extinction. Our results show that both geometrical factors and shock physics can significantly affect the profile morphology. In a companion paper we will apply this model to Fabry–Perot observations of bow shocks in the Orion BN–KL outflow.  相似文献   

Perceptible earthquakes in the United Kingdom   总被引：1，自引：0，他引：1  

Paul W. Burton 《Geophysical Journal International》1978,54(2):475-479

Summary. Earthquake occurrence in the United Kingdom is analysed using Gumbel's third type asymptotic distribution of extreme values. Uncertainties in both the parameters and predictions derived from the Gumbel distribution are obtained and it is shown that an earthquake with body-wave magnitude slightly over five is the one most likely to be perceived at any point in the United Kingdom.  相似文献   

EXPERIMENTS ON THE STABILITY OF FeOOH ON THE SURFACE OF THE MOON     

Lawrence A. Taylor  Jacqueline C. Burton 《Meteoritics & planetary science》1976,11(3):225-230

The FeOOH phase in Apollo 16 rocks is akaganéite. Other polymorphs of FeOOH, i.e. geothite and lepidocrocite, may exist but have not been identified by X-ray diffraction. Experiments performed during this study using akaganéite, geothite, and lepidocrocite placed at 135°C and under a pumping vacuum of 10^?2 torr, demonstrate that these forms of FeOOH are not stable on the surface of the Moon, where daytime temperatures are about 140°C and pressures are about 10^?7 torr. The effect of the vacuum is to strip off the water, and the temperature speeds up this dehydration process. These data lend support to the contention of Taylor et al. (1973) that the FeOOH in lunar rocks formed by the oxyhydration of lawrencite, FeCl₂, due to contamination by terrestrial water vapor.  相似文献   

Observations of shocked H2 and [FeII] line profiles in orion bullet wakes     

Jonathan A. Tedds  Peter W. J. L. Brand  Michael G. Burton  Antonio Chrysostomou  Amadeu J. L. Fernandes 《Astrophysics and Space Science》1995,233(1-2):39-44

New observations of H₂ velocity profiles in the Orion bullet wakes are extremely difficult to reconcile with existing steady-state shock models. We have observed [FeII] 1.644µm velocity profiles of selected bullets and H₂ 1-0 S(1) 2.122µm velocity profiles for a series of positions along and across the corresponding bow-shock wakes. Integrated [FeII] velocity profiles of the brightest bullets are consistent with theoretical bow shock predictions. Observations of broad, singly-peaked H₂ 1-0 S(1) profiles in the most clearly resolved bullet wakes challenge our understanding of molecular shocks. It may be necessary to model the effects of instabilities and turbulence in the Orion bullet wakes in order to fit our observations.  相似文献   

Upper crustal shear velocity models from higher mode Rayleigh wave dispersion in Scotland   总被引：1，自引：0，他引：1  

Colin D. MacBeth  Paul W. Burton 《Geophysical Journal International》1985,83(2):519-539

Summary. Group velocities for first and second higher mode Rayleigh waves, in the frequency range 0.8–4.8 Hz, generated from a local earthquake of magnitude 3.7 M _L in western Scotland, are measured at stations along the 1974 LISPB line. These provide detailed information about the crustal structure west of the line. The data divide the region into seven apparently homogeneous provinces. Averaged higher mode velocity dispersion curves for each province are analysed simultaneously using a linearized inversion technique, yielding regionalized shear velocity profiles down to a depth of 17 km into the upper crust. Shear wave velocity is between 3.0 and 3.4 km s⁻¹ in the upper 2 km, with a slow increase to around 3.8 km s⁻¹. P -wave models computed using these results agree with profiles from the LISPB and LUST refraction experiments.  相似文献   

MicroRaman spectroscopy of diamond and graphite in Almahata Sitta and comparison with other ureilites     

Aidan J. ROSS  Andrew STEELE  Marc D. FRIES  Lukas KATER  Hilary DOWNES  Adrian P. JONES  Caroline L. SMITH  Peter M. JENNISKENS  Michael E. ZOLENSKY  Muawia H. SHADDAD 《Meteoritics & planetary science》2011,46(3):364-378

This work is the first detailed study of carbon phases in the ureilite Almahata Sitta (sample #7). We present microRaman data for diamond and graphite in Almahata Sitta, seven unbrecciated ureilites, and two brecciated ureilites. Diamond in Almahata Sitta was found to be distinct from that in unbrecciated and brecciated ureilites, although diamond in unbrecciated and brecciated ureilites is indistinguishable. Almahata Sitta diamond shows a peak center range of 1318.5–1330.2 cm^?1 and a full width at half maximum (FWHM) range of 6.6–17.4 cm^?1, representing a shock pressure of at least 60 kbar. The actual peak shock pressure may be higher than this due to postshock annealing, if shock synthesis is the source of ureilite diamonds. Diamond in unbrecciated and brecciated ureilites have peak center wave numbers closer to terrestrial kimberlite diamond, but show a wider range of FWHM than Almahata Sitta. The larger peak shift observed in Almahata Sitta may indicate the presence of lonsdaleite. Alternatively, the lower values in brecciated ureilites may be evidence of an annealing step either following the initial diamond‐generating shock or as a consequence of heating during reconsolidation of the breccia. Graphite in Almahata Sitta shows a G‐band peak center range of 1569.1–1577.1 cm^?1 and a G‐band FWHM range of 24.3–41.6 cm^?1 representing a formation temperature of 990 ± 120 °C. Amorphous carbon was also found. We examine the different theories for diamond formation in ureilites, such as chemical vapor deposition and shock origin from graphite, and explore explanations for the differences between Almahata Sitta and other ureilites.  相似文献   

A comment on: ‘TitaniQ under pressure: the effect of pressure and temperature on the solubility of Ti in quartz’, by Jay B. Thomas,E. Bruce Watson,Frank S. Spear,Philip T. Shemella,Saroj K. Nayak and Antonio Lanzirotti     

Colin J. N. Wilson  Terry M. Seward  Aidan S. R. Allan  Bruce L. A. Charlier  Léa Bello 《Contributions to Mineralogy and Petrology》2012,164(2):359-368

Trace concentrations of Ti in quartz are used to indicate the pressure and temperature conditions of crystallization in the ‘TitaniQ’ geothermobarometer of Thomas et al. (Contrib Miner Petrol 160:743–759, 2010). It utilises the partitioning of Ti into quartz as an indicator of the pressures and/or temperatures of crystal growth. For a given value of TiO₂ activity in the system, if temperatures are inferred to ±20 °C, pressure is constrained to ±1 kbar and vice versa. There are significant contrasts, however, between the conclusions from TitaniQ and those for natural quartz (as well as other mineral phases) in volcanic rocks. Application of the TitaniQ model to quartz from the 27 ka Oruanui and 760 ka Bishop high-silica rhyolites, where the values of T, P and TiO₂ activity are constrained by other means (Fe–Ti oxide equilibria, melt inclusion entrapment pressures in gas-saturated melts, melt and amphibole compositions), yields inconsistent results. If realistic values are given to any two of these three parameters, then the value of the third is wholly unrealistic. The model yields growth temperatures at or below the granite solidus, pressures in the lower crust or upper mantle, or TiO₂ activities inconsistent with the mineralogical and chemical compositions of the magmas. CL imagery and measurements of Ti (and other elements) in quartz are of great value in showing the growth histories and changes in conditions experienced by crystals, but direct linkages to P, T conditions during crystal growth cannot be achieved.  相似文献   

The solar limb emission spectrum between 300 Å and 2803 Å     

W. M. Burton  A. Ridgeley 《Solar physics》1970,14(1):3-28

The spectrum of the solar limb has been recorded in the wavelength region 300–2803 Å using instrumentation carried in Skylark rockets. More than 600 emission lines have been observed of which about 500 have firm identifications, while 50 lines remain unidentified. A complete list of observed emission lines is given together with estimated line intensities and comments on the identifications.  相似文献   

Reactive sulfide relationships with trace metal extractability in sediments from southern Moreton Bay, Australia   总被引：1，自引：0，他引：1  

Burton ED  Phillips IR  Hawker DW 《Marine pollution bulletin》2005,50(5):589-595

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