EIN AUTOMATISCHES VERFAHREN ZUR INTERPRETATION MAGNETISCHER ANOMALIEN NACH DER METHODE DER KLEINSTEN QUADRATE*

The interpretation of magnetic anomalies on the basis of model bodies is preferably done by making use of “trial and error” methods. These manual methods are tedious and time consuming but they can be transferred to the computer by making the required adjustments by way of the method of least squares. The general principles of the method are described. Essential presumptions are the following:

• 1 the assumption of definite model bodies
• 2 the existence of approximation values of the unknown quantities (position, dip, magnetization, etc.)
• 3 a sufficiently large number of measuring values, so that the process of adjustment can be carried out.

The advantages of the method are the following:

• 1 substantial automatization and a quick procedure by using computers
• 2 determination of the errors of the unknown quantities.

The method was applied to the interpretation of two-dimensional ΔZ- and ΔT-anomalies. Three types of model bodies are taken as basis of the computer program, viz. the thin dyke, infinite resp. finite in its extension downward and the circular cylinder. Only the measuring values are given to the computer. The interpretation proceeds in the following steps:

• 1 calculation of approximation values
• 2 determination of the model body of best fit
• 3 iteration in the case of the model body of best fit.

The computer produces the end values of the unknown quantities, their mean errors, and the pertaining theoretical anomalies. These end results are given to a plotting machine, which draws the measured curve, the theoretical curve and the model bodies. Interpretation examples are given.     

IMPEDANCE OF A PLANE ELECTROMAGNETIC WAVE AT THE SURFACE OF A LAYERED CONDUCTING EARTH WITH DIPPING ANISOTROPY*

The problem of a plane wave incident on a non-isotropic dipping layer lying over an isotropic conducting substratum has been studied and some numerical results are presented to show the effects of

• 1) degree of anisotropy m,
• 2) conductivity contrast between the substratum to the upper layer b,
• 3) angle of inclination of the axis of anisotropy α,

on the variation of amplitude and phase difference of the wave impedance with the normalized skin-depth (d/δ₁).     

GEOPHYSICAL ANOMALY INTERPRETATION OF POTENTIAL FIELDS BY MEANS OF SINGULAR POINTS METHOD AND FILTERING*

The calculation of potential field anomalies on different levels below the measuring level permits to localize the singular points related to the sources of anomalies. It is possible to achieve considerable improvement of the resolution of this method

• 1) filtering of analytical downward continuation,
• 2) the use of the magnitude of the gravitational vector,
• 3) calculation of physe changes.

The numerical examples confirm these assumptions.     

Studies on the Toxicity of a few Pesticides on Colisa fasciatus and Notopterus notopterus with Reference to Histopathology and Histochemistry. Part 1: Bioassay Studies

An attempt has been made to study the toxicity of two commonly used pesticides aldrin (organochlorine) and ethyl-parathion (organophosphorus) to the fish Colisa fasciatus (Anabantidae) and Notopterus notopterus (Notopteridae). During bioassay studies, the behaviour of the fishes was recorded. The aldrin concentration used lies between 0.021 mg/1 and 0.042 mg/1 for C. fasciatus and 0.00056 mg/1 and 0.00135 mg/1 for N. notopterus. The ethyl-parathion concentration used lies between 1.8 mg/1 and 3.7 mg/1 for C. fasciatus and 0.49 mg/1 and 1.00 mg/1 for N. notopterus.

• – The effect of lethal aqueous concentrations of pesticides on the Fishes prior to death are usually manifested by excitation, erratic swimming ability, difficulty in respiration, increasing in ventilation rate, jerky movements of body and fin fast, up- and downward movements, convulsions, loss of equilibrium, loss of the original colour of the body skin and the excess secretion of mucus by the gills and the body wall.
• – the TL_m values for 24, 48 and 96 hours of exposition are determined for both species of fish and both pesticides at the following variables:

• ? three levels of temperature,
• ? three levels of dissolved oxygen,
• ? three levels of pH,
• ? three fish sizes.

• – statistical analysis of variance shows, that all variables have a significant effect on the TL_m values of both pesticides for both fish species;
• – Aldrin (chlorinated hydrocarbon) is more toxic than ethylparathion (organophosphate) at all variables;
• – Colisa fasciatus is the more resistant species than Notopterus notopterus.
• – the relationship between the total number of the fishes N₀, survival numbers N and time t can be expressed by a mathematical formula as:
• – the harmless concentration to C. fasciatus ranged from 0.0049 mg/1 to 0.0161 for aldrin, 0.54 mg/1 to 0.99 mg/1 for ethyl-parathion and to N. notopterus from 0.00012 mg/1 to 0.00045 mg/1 for aldrin, 0.10 mg/1 to 0.21 mg/1 for ethyl-parathion;
• – the aldrin should be diluted at least 4000 times and ethyl-parathion 320 times of its actual concentration.

     

A COMPARISON BETWEEN WIENER FILTERING,KALMAN FILTERING,AND DETERMINISTIC LEAST SQUARES ESTIMATION*

The least squares estimation procedures used in different disciplines can be classified in four categories:

• a. Wiener filtering,
• b. b. Autoregressive estimation,
• c. c. Kalman filtering,
• d. d. Recursive least squares estimation.

The recursive least squares estimator is the time average form of the Kalman filter. Likewise, the autoregressive estimator is the time average form of the Wiener filter. Both the Kalman and the Wiener filters use ensemble averages and can basically be constructed without having a particular measurement realisation available. It follows that seismic deconvolution should be based either on autoregression theory or on recursive least squares estimation theory rather than on the normally used Wiener or Kalman theory. A consequence of this change is the need to apply significance tests on the filter coefficients. The recursive least squares estimation theory is particularly suitable for solving the time variant deconvolution problem.     

Antiplane dynamic soil-bridge interaction for incident plane SH-waves

The analysis of dynamic soil-bridge interaction has been performed in three steps. These are:

• 1. The analysis of input motions.
• 2. The force-displacement relationships for the foundations.
• 3. The dynamic analysis of the structure itself, i.e. the bridge.

Based on the exact solution of the first two steps, the dynamic interaction of a simple two-dimensional bridge model erected on an elastic half-space has been investigated for a single span case. The two-dimensional model under study consists of an elastic shear girder bridge supported by two rigid abutments and rigid foundations which have a circular cross-section and are welded to the half-space. It has been shown that the dynamic interaction depends on:

• 1. The incidence angle of plane SH-waves.
• 2. The ratio of the rigidity of the girder and the soil.
• 3. The ratio of the girder mass to the mass of the rigid abutment-foundation system.
• 4. The span of the bridge.

The dynamic response of the girder and the effect of the radiative damping in the half-space on the interaction of the girder have been studied.     

DEVELOPMENT OF MORE EFFICIENT AIRGUN ARRAYS: THEORY AND EXPERIMENT*

Source strength of an airgun array may be increased by:

• — utilizing higher pressure,
• — increasing total array volume,
• — employing more guns,
• — improving gun efficiency.

One measure of gun efficiency is “specific source strength”, P_a*, defined as source strength per unit quantity of air used. Typical units are MPa m/l. Most developments are directed toward increasing gun pressure and/or gun volume to increase source strength of the array. These efforts require that more air compressors be installed onboard the ship. Consequently, a larger ship may be needed for the additional compressors, guns, and auxiliary equipment. A development program was initiated in 1976 to increase source strength of the array without using a larger ship. New guns were designed and built—one for 41.4 MPa and 7.37 liter (6000 p.s.i./450 in³) operation and another with 13.8 MPa and 4.92 liter (2000 p.s.i./300 in³) capability. Experiments were conducted with these new guns (and existing guns) over a range of pressures from 13.8 to 41.4 MPa (2000 to 6000 p.s.i.). Design of the new guns was aided by a mathematical model. The model relates physical dimensions of the airgun to acoustic pressure in the water. It consists of four nonlinear differential equations relating

• — shuttle motion,
• — bubble pressure,
• — chamber pressure,
• — bubble radius.

The last equation is the “free-bubble-oscillation equation” and represents the ideal case of a pressurized bubble released instantaneously in water. The three other equations modify this ideal case; the four equations together model an airgun of the type manufactured by Bolt Associates, Inc.     

Conference listing

• World Water and Environmental Resources Congress
• Salt Lake City, USA
• 27 June–1 July 2004
• Website: http://www.asce.org/conferences/ewri2004

• DEFRA Flood and Coastal Management Conference
• York, UK
• 29 June–1 July 2004
• Email: rceg@defra.gsi.gov.uk

• 2nd Asia Pacific Association of Hydrology and Water Resources (APHW) Conference
• Singapore
• 5–8 July 2004

• Watershed 2004
• Michigan, USA
• 11–14 July 2004
• Website: http://www.wef.org/conferences

• BHS International Conference on ‘Hydrology: Science and Practise for the 21^st Century’
• Imperial College, London
• 12–16 July 2004
• Contact: Dr Adrian Butler
• Tel: 020 7954 6122 Fax: 020 7594 6124
• E‐mail: a.butler@ic.ac.uk
• Website: http://www.hydrology.org.uk/index.html

• XXIII Nordic Hydrological Conference
• Tallinn, Estonia
• 8–12 August 2004
• Website: http://www.emhi.ee/english.English_Hydr_Inter‐new.php3

• Hydro Vision 2004 Best Practices, New Ideas, Opportunities
• Montreal, Canada
• 16–20 August 2004
• Website: http://www.hcipub.com/hydrovision/index.asp

• World Water Week and Symposium
• Stockholm, Sweden
• 16–20 August 2004
• Website: http://www.siwi.org

• Italia 2004 32^nd International Geological Congress “From the Mediterranean Area Toward a Global Geological Renaissance” Geology, Natural Hazards and Cultural Heritage
• Florence
• 20–28 August 2004
• Contact: Chiara Manetti, Dipartimento di Scienze della Terra, Via La Pira, 4‐50121 Firenze, Italy
• Tel/Fax: +39 055 2382146
• Email: casaitalia@geo.unifi.it

• Good Water Governance for People & Nature: What Roles for Law, Institutions, Science & Finance
• Dundee, Scotland
• 29 August–1 September 2004
• Website: http://www.awra.org/meetings/Dundee2004/index.html

• XXII Conference of the Danubian Countries on the Hydrological Forecasting and Hydrological Bases of Water Management
• Brno, Czech Republic
• 30 August–2 September 2004
• Email: michelot@geol.u‐psud.fr

• International Conference on Hydrology of Mountain Environments
• Berchtesgaden, Germany
• 27 September–1 October 2004
• Email: schroeder@bafg.de

• XXXIII Congress of IAH—Conference on Groundwater Flow Understanding: From Local to Regional Scale. Joint Conference IAH/ALHSUD
• Mexico
• 11–15 October 2004
• E‐mail: aih@igris.igeograf.unam.mx
• Website: www.igeograf.unam.mx/aih

• Hydro4
• Galway, Ireland
• 2–4 November 2004
• Contact: Susan Haley, Hydro4, 74 Callington Road, Saltash, Cornwall, PL12 6DY, UK
• E‐mail: hydro4@hydrographicsociety.org

• International Association of Hydrological Sciences Scientific Assembly
• Foz do lguaçu, Brazil
• 3–9 April 2005
• Website: www.cig.ensmp.fr/～iahs

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

• 10th International Symposium on the Interactions between Sediments and Water
• Lake Bled, Slovenia
• 28th August–2nd September 2005
• Website: http://www.wsc.monash.edu.au/iasws/2005symposium.htm

• EnvironmexAsia2
• Singapore
• 29th November–2nd December 2005
• Website: http://www.environmexasia.com

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

Conference listing

• World Water and Environmental Resources Congress
• Salt Lake City, USA
• 27 June–1 July 2004
• Website: http://www.asce.org/conferences/ewri2004

• DEFRA Flood and Coastal Management Conference
• York, UK
• 29 June–1 July 2004
• Email: rceg@defra.gsi.gov.uk

• 2nd Asia Pacific Association of Hydrology and Water Resources (APHW) Conference
• Singapore
• 5–8 July 2004

• Watershed 2004
• Michigan, USA
• 11–14 July 2004
• Website: http://www.wef.org/conferences

• BHS International Conference on ‘Hydrology: Science and Practise for the 21^st Century’
• Imperial College, London
• 12–16 July 2004
• Contact: Dr Adrian Butler
• Tel: 020 7954 6122 Fax: 020 7594 6124
• E‐mail: a.butler@ic.ac.uk
• Website: http://www.hydrology.org.uk/index.html

• XXIII Nordic Hydrological Conference
• Tallinn, Estonia
• 8–12 August 2004
• Website: http://www.emhi.ee/english.English_Hydr_Inter‐new.php3

• Hydro Vision 2004 Best Practices, New Ideas, Opportunities
• Montreal, Canada
• 16–20 August 2004
• Website: http://www.hcipub.com/hydrovision/index.asp

• World Water Week and Symposium
• Stockholm, Sweden
• 16–20 August 2004
• Website: http://www.siwi.org

• Italia 2004 32^nd International Geological Congress “From the Mediterranean Area Toward a Global Geological Renaissance” Geology, Natural Hazards and Cultural Heritage
• Florence
• 20–28 August 2004
• Contact: Chiara Manetti, Dipartimento di Scienze della Terra, Via La Pira, 4‐50121 Firenze, Italy
• Tel/Fax: +39 055 2382146
• Email: casaitalia@geo.unifi.it

• Good Water Governance for People & Nature: What Roles for Law, Institutions, Science & Finance
• Dundee, Scotland
• 29 August–1 September 2004
• Website: http://www.awra.org/meetings/Dundee2004/index.html

• XXII Conference of the Danubian Countries on the Hydrological Forecasting and Hydrological Bases of Water Management
• Brno, Czech Republic
• 30 August–2 September 2004
• Email: michelot@geol.u‐psud.fr

• International Conference on Hydrology of Mountain Environments
• Berchtesgaden, Germany
• 27 September–1 October 2004
• Email: schroeder@bafg.de

• XXXIII Congress of IAH—Conference on Groundwater Flow Understanding: From Local to Regional Scale. Joint Conference IAH/ALHSUD
• Mexico
• 11–15 October 2004
• E‐mail: aih@igris.igeograf.unam.mx
• Website: www.igeograf.unam.mx/aih

• Hydro4
• Galway, Ireland
• 2–4 November 2004
• Contact: Susan Haley, Hydro4, 74 Callington Road, Saltash, Cornwall, PL12 6DY, UK
• E‐mail: hydro4@hydrographicsociety.org

• International Association of Hydrological Sciences Scientific Assembly
• Foz do lguaçu, Brazil
• 3–9 April 2005
• Website: www.cig.ensmp.fr/～iahs

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

• 10th International Symposium on the Interactions between Sediments and Water
• Lake Bled, Slovenia
• 28th August–2nd September 2005
• Website: http://www.wsc.monash.edu.au/iasws/2005symposium.htm

• EnvironmexAsia2
• Singapore
• 29th November–2nd December 2005
• Website: http://www.environmexasia.com

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

Analysis of riverbank instability due to toe scour and lateral erosion

This paper provides instruction in the use of the computer spreadsheet to undertake the calculations necessary to apply the Osman–Thorne bank stability analysis for steep, eroding riverbanks. The guide explains how to input the necessary parameters into the LOTUS 123 spreadsheet in order to:

• 1 find the initial factor of safety of the bank with respect to slab-type failure;
• 2 test the sensitivity of bank stability to changes in the engineering properties of the bank material;
• 3 analyse the response of bank stability to toe scour and/or lateral erosion and find the critical condition;
• 4 find the geometry of the failure surface and failure block;
• 5 analyse the response of bank stability to further toe scour and/or lateral erosion;
• 6 find the geometry of the failure surface and failure block in subsequent failures.

     

Conference listing

• WEFTEC 2000,73rd Annual Conference & Exposition
• Anaheim Convention Center, Anaheim, California, USA
• 14 ‐ 18 October 2000
• >Website: http://www.wef.org/Weftec/index.htm

• International Water Conference 2000
• Engineer's Society of W. PA, Pittsburgh, PA
• 22 ‐ 27 October 2000
• Tel: 412‐261‐0710; Fax: 412‐261‐1606

• ICID IEC meeting and joint International Micro Irrigation Congress
• Capetown, South Africa
• 22 ‐ 27 October 2000
• Website: http://www.icid.org/

• Association of Water Technologies, Annual Convention and Exposition
• Association of Water Technologies, Honolulu, HI
• 31 October ‐ 4 November 2000
• Tel: 800‐858‐6683; Fax: 703‐610‐9005

• International Irrigation Show
• Irrigation Association, Phoenix, AZ
• 12 ‐ 14 November 2000
• Tel: 703‐573‐3551; Fax: 703‐573‐1913

• Summit 2000—Annual Meeting & Exposition
• Geological Society of America, Reno, NV
• 12 ‐ 15 November 2000
• Tel: 303‐447‐2020; Fax: 303‐447‐0648

• National Irrigation Symposium
• ASAE, Phoenix, AZ
• 12 ‐ 16 November 2000
• Tel: 616‐428‐6327

• Hydro 2000, 3rd International Hydrology and Water Resources Symposium
• Perth, Western Australia
• 20 ‐ 23 November 2000
• Theme: Interactive hydrology: interactions between hydrology and climate, environment, economics and society. E‐mail: conwes@congresswest.com.au. Website: http://www.ieaust.org.au/hydro2000

• Fresh Perspectives—Limnology, Hydrology, Meteorology
• University of Canterbury, Christchurch, New Zealand
• 20 ‐ 24 November 2000
• Website: http://www.phys.canterbury.ac.nz/conf/fresh.html

• International Association of Hydrogeologists 30th International Congress 2000 Groundwater Division: Geological Society of South Africa
• Education Faculty, Universty of Cape Town
• 26 November ‐ 1 December 2000
• Theme: Groundwater: Past achievements and future challenges. Contact: IAH Secretariat, Deidre Cloete, Conference Secretariat: IAH Congress: Cape Town 2000, PO Box 452, Stellenbosch. Tel: 2721 886 4496; Fax: 2721 883 8177; E‐mail: deidre@iafrica.com

• 20th Australian Groundwater School
• Centre for Groundwater Studies, Melbourne, Australia
• 27 November ‐ 2 December 2000
• Tel: 61‐8‐8303‐8753; Fax: 61‐8‐8303‐8730

• Water Resource and Reservoir Workshop
• 12 December 2000
• Contact: Hydrocomp, Inc., 3 Lagoon Drive, Suite 150, Redwood City, CA 94065. Tel: (415) 637 9060; Website: http://www.hydrocomp.com/ResRCInfo.html

• AGU, American Geophysical Union, San Francisco
• 15 ‐ 19 December 2000
• Website: http://earth.aqu.org

• International Conference On Integrated Water Resources. Management for Sustainable Development
• Roorkee, India
• 19 ‐ 21 December 2000
• Contact: Dr B Soni, Scientist F and Organising Secretary, National Institute of Hydrology, Roorkee‐24667 (U.P.), India. Fax: 0091 1332 72123; E‐mail: bsoni@cc.nih.ernet.in

• International Symposium on Preferential Flow (held in conjunction with the International Soil Erosion Symposium)
• Phoenix, Arizona
• 3 ‐ 5 January 2001
• E‐mail: shafer@asae.org Website: www.asae.org

• Symposium on the Role of Drought in Aquatic Ecosystems
• Albury, Australia
• February 2001
• Contact: The Organizing Committee, Symposium on the Role of Drought in Aquatic Ecosystems, Murray–Darling Freshwater Research Centre and The CRC for Freshwater Ecology, PO Box 921, Albury, NSW 2640, Australia. E‐mail: hump@mdfrc.canberra.edu.au (include the word ‘Symposium’ in the subject heading)

• ACWI, Advisory Committee on Water Information, Conference on TMDL Science Issues
• St Louis, MO
• 4 ‐ 7 March 2001
• Website: http://water.usgs.gov/wicp/upcom.html

• Groundwater Quality 2001. 3rd International Conference
• University of Sheffield,UK
• 18 ‐ 21 June 2001
• Contact: GQ2001 Conference Secretariat, GPRG, Department of Civil and Structural Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK. E‐mail: gq2001@sheffield.ac.uk; Website: http://www.shef.ac.uk/∽gq2001/

• The First International Conference on Saltwater Intrusion and Coastal Aquifers‐Monitoring, Modelling and Management
• Essaouira, Morocco
• 18 ‐ 25 April 2001
• Contact: Alexander H‐D Cheng, Department of Civil & Environmental Engineering, University of Delaware, Newark, Delaware 19716, USA. Tel: 302 831 6787; Fax: 302 831 3640; E‐mail: cheng@ce.udel.edu; Website: http://www.uwin.siu.edu/dir_announce/event/2001/event0418.html

• Changing Wetlands: new developments in wetland science
• 11 ‐ 13 September 2001
• Contact: Conference Secretary, Changing Wetlands Conference, Sheffield Wetlands Research Centre (SWeRC) Department of Geography, University of Sheffield, Sheffield S10 2TN, UK. Fax: +44 (0)114 279 7912; E‐mail: wetlands@sheffield.ac.uk; Website: http://www.shef.ac.uk/∽g/wetlands/index.html

• XXXI Congress, International Association of Hydrogeologists
• Munich, Germany
• 10 ‐ 14 September 2001
• Website: http://agh.iaag.geo.uni‐muenchen.de

If you would like your conference included please E‐mail details to Stephen Henning. E‐mail: shenning@wiley.co.uk     

THE USE OF SEISMIC SHEAR WAVES AND COMPRESSIONAL WAVES FOR LITHOLOGICAL PROBLEMS OF SHALLOW SEDIMENTS*

From a great variety of in situ shear wave experiments, i.e., reflection, refraction and borehole surveys in the shallow sediments of the north German plains, several specific properties have been derived. Shear waves (S) differ from compressional waves (P) in that:

• 1 they are not affected by the degree of water saturation. Thus, they provide a better correlation between the velocity V_s and (solid) lithology;
• 2 they generally have lower frequencies, but shorter wavelength and, hence, a better resolution of thin layers;
• 3 they have lower absorption Q_s^?1 and hence a better penetration in partially saturated and gas-containing sediments than P-waves.

Correlations have been established between V_s and the confining pressure and between reduced V_s values and several lithological parameters like the grain size of sandy material. More lithological and hydrological information is obtained by using S- and P-wave surveys along the same profile. The best information on a sedimentological structure is obtained by the simultaneous observation of V_s, V_p, Q_s and Q_p.     

FIRST EXPERIENCE AND RESULTS WITH A NEW SEISMIC INTERPRETATION METHOD*

At the EAEG meeting in Venice (May 1969) Linsser presented a new method for the interpretation of seismic measurements (“Transformation of Seismic Data into Geological Models by Digital Template Analysis”). First results were presented during the S.E.G. convention in Calgary (September 1969). Meanwhile some experience concerning the possibility of the application of this method is available. Starting from the fact that the computer is able to store several physical parameters (amplitude, wave-length, direction of the seismic event, coincidence with a template and the beginning and the end of each reflection), the importance of these data for the investigation of special geophysical questions will be discussed. This method has been tested with several examples on the following problems:

• 1 Proving and exact localisation of faults.
• 2 Investigation of velocities of interesting layers.
• 3 Additional information for the geological interpretation of seismic sections.
• 4 Picking of weak reflections in the “Pre-Zechsteinian” in Northern Germany.

Finally the possibilities of further applications and developments are discussed.     

THE KALMAN FILTER AS A PREDICTION ERROR FILTER*

In mathematical statistical filtering the deconvolution problem can be solved by two different methods:

• 1 by inverse filtering
• 2 by calculating the prediction error.

Both methods are well known in the theory of Wiener filters. If, however, the generating process of the signal is known and can be described by a set of linear first order differential equations, then the Kalman filter can also be used to solve the deconvolution problem. In the case of the inverse filtering method this was shown by Bayless and Brigham (1970). But, while their method can only be used if the original signal is a colored random process, this paper shows that in the case of a white process the prediction error filtering method is a more appropriate approach. The method is extremely efficient and simple. This can be demonstrated by an example which maybe of special interest for seismic exploration.     

Phylogenetic systematics of chelonioid sea turtles

Abstract Chelonioid sea turtles (Order Testudinata; Superfamily Chelonioidea) first appear in the early Cretaceous (Aptian-Albian). Their long fossil record is excellent compared to most marine tetrapods. Nonetheless, there has been no inclusive attempt to provide an analysis of cladistic relationships among this group. In this paper, the following chelonioid classification is proposed, based on 76 characters among 20 fossil and six living well- represented genera:

• 1 Family Cheloniidae (Coniacian to Recent); Toxochelys, Ctenochelys, Osteopygis, Erquelinnesia, Allopleuron, Argillochelys, Puppigerus, Eochelone, Syllomus, Natator, Eretmochelys, Chelonia, Caretta, Lepidochelys
• 2 Family Protostegidae (Aptian to Maastrichtian?); ‘Santana new protostegid’,Rhinochelys, Notochelone, Desmatochelys, Chelosphargis, Protostega, Archelon
• 3 Family Dermochelyidae (Santonian? to Recent); Corsochelys, ‘HMG new dermo-chelyid’, Eosphargis, Psephophorus, Dermochelys.

     

Conference listing

• European Geosciences Union, 1st General Assembly
• Nice, France
• 25–30 April 2004
• Website: http://www.copernicus.org/EGU/ga/egu/04

• Geographic Information Systems (GIS) and Water Resources III
• Nashville, TN
• 17–19 May 2004
• Website: http://www.awra.org/meetings/Nashville2004/index.html

• CGU/AGU/SEG
• Montreal, Quebec
• 17–21 May 2004
• Website: http://www.agu.org/meetings/sm04/

• North American Genthological Society Meeting
• Vancouver, BC
• 6–10 June 2004
• Website: http://benthos.org/index.cfm

• 61 Eastern Snow Conference
• Portland, Maine, USA
• 9–11 June 2004
• Website: http://www.easternsnow.org/

• International Conference on Groundwater Vulnerability Assessment and Mapping
• Sosnowiec, Poland
• 16–19 June 2004
• Contact: Dr Andrzej J. Witkowski, Secretariat of the Conference, University of Silesia, B?dzińska Str., 60, 41‐200 Sosnowiec, Poland
• Tel: +48 32 291 68 88
• Fax: +48 32 291 58 65
• E‐mail: switkows@us.edu.pl
• Website: http://khgi.wnoz.us.edu.pl/vulnerability.htm

• Riverflow 2004–Second International Conference on Fluvial Hydraulics
• Naples, Italy
• 23–25 June 2004
• Website: http://www.riverflow2004.unina.it

• Riparian Ecosystems and Buffers: Multi‐Scale Structure, Function and Management
• Olympic Valley, CA
• 28–30 June 2004
• Website: http://www.awra.org/Olympic2004/index.html

• BHS International Conference on ‘Hydrology: Science and Practise for the 21^st Century’
• Imperial College, London
• 12–16 July 2004
• Contact: Dr Adrian Butler
• Tel: 020 7954 6122 Fax: 020 7594 6124
• E‐mail: a.butler@ic.ac.uk
• Website: http://www.hydrology.org.uk/index.html

• Italia 2004 32^nd International Geological Congress “From the Mediterranean Area Toward a Global Geological Renaissance” Geology, Natural Hazards and Cultural Heritage
• Florence
• 20–28 August 2004
• Contact: Chiara Manetti, Dipartimento di Scienze della Terra, Via La Pira, 4‐50121 Firenze, Italy
• Tel/Fax: +39 055 2382146
• Email: casaitalia@geo.unifi.it

• Good Water Governance for People & Nature: What Roles for Law, Institutions, Science & Finance
• Dundee, Scotland
• 29 August–1 September 2004
• Website: http://www.awra.org/meetings/Dundee2004/index.html

• XXXIII Congress of IAH—Conference on Groundwater Flow Understanding: From Local to Regional Scale. Joint Conference IAH/ALHSUD
• Mexico
• 11–15 October 2004
• E‐mail: aih@igris.igeograf.unam.mx
• Website: www.igeograf.unam.mx/aih

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

Conference listing

• Geographic Information Systems (GIS) and Water Resources III
• Nashville, TN
• 17–19 May 2004
• Website: http://www.awra.org/meetings/Nashville2004/index.html

• CGU/AGU/SEG
• Montreal, Quebec
• 17–21 May 2004
• Website: http://www.agu.org/meetings/sm04/

• North American Genthological Society Meeting
• Vancouver, BC
• 6–10 June 2004
• Website: http://benthos.org/index.cfm

• 61 Eastern Snow Conference
• Portland, Maine, USA
• 9–11 June 2004
• Website: http://www.easternsnow.org/

• International Conference on Groundwater Vulnerability Assessment and Mapping
• Sosnowiec, Poland
• 16–19 June 2004
• Contact: Dr Andrzej J. Witkowski, Secretariat of the Conference, University of Silesia, B?dzińska Str., 60, 41‐200 Sosnowiec, Poland
• Tel: +48 32 291 68 88
• Fax: +48 32 291 58 65
• E‐mail: switkows@us.edu.pl
• Website: http://khgi.wnoz.us.edu.pl/vulnerability.htm

• Riverflow 2004–Second International Conference on Fluvial Hydraulics
• Naples, Italy
• 23–25 June 2004
• Website: http://www.riverflow2004.unina.it

• Riparian Ecosystems and Buffers: Multi‐Scale Structure, Function and Management
• Olympic Valley, CA
• 28–30 June 2004
• Website: http://www.awra.org/Olympic2004/index.html

• BHS International Conference on ‘Hydrology: Science and Practise for the 21^st Century’
• Imperial College, London
• 12–16 July 2004
• Contact: Dr Adrian Butler
• Tel: 020 7954 6122 Fax: 020 7594 6124
• E‐mail: a.butler@ic.ac.uk
• Website: http://www.hydrology.org.uk/index.html

• Italia 2004 32^nd International Geological Congress “From the Mediterranean Area Toward a Global Geological Renaissance” Geology, Natural Hazards and Cultural Heritage
• Florence
• 20–28 August 2004
• Contact: Chiara Manetti, Dipartimento di Scienze della Terra, Via La Pira, 4‐50121 Firenze, Italy
• Tel/Fax: +39 055 2382146
• Email: casaitalia@geo.unifi.it

• Good Water Governance for People & Nature: What Roles for Law, Institutions, Science & Finance
• Dundee, Scotland
• 29 August–1 September 2004
• Website: http://www.awra.org/meetings/Dundee2004/index.html

• XXXIII Congress of IAH—Conference on Groundwater Flow Understanding: From Local to Regional Scale. Joint Conference IAH/ALHSUD
• Mexico
• 11–15 October 2004
• E‐mail: aih@igris.igeograf.unam.mx
• Website: www.igeograf.unam.mx/aih

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

Conference listing

• AGI 2004 Ocean Sciences Meeting
• Portland, Oregon, USA
• 26–30 January 2004
• Sponsor: AGU
• Contact: A Singer, AGU, 2000 Florida Avenue, NW, Washington, DC 20009, USA
• Tel: +1 202 777 7340
• Fax: +1 202 328 0566
• E‐mail: asinger@agu.org
• Website: agu.org/meetings/

• European Geosciences Union, 1st General Assembly
• Nice, France
• 25–30 April 2004
• Website: http://www.copernicus.org/EGU/ga/egu/04

• Geographic Information Systems (GIS) and Water Resources III
• Nashville, TN
• 17–19 May 2004
• Website: http://www.awra.org/meetings/Nashville2004/index.html

• CGU/AGU/SEG
• Montreal, Quebec
• 17–21 May 2004
• Website: http://www.agu.org/meetings/sm04/

• North American Genthological Society Meeting
• Vancouver, BC
• 6–10 June 2004
• Website: http://benthos.org/index.cfm

• 61 Eastern Snow Conference
• Portland, Maine, USA
• 9–11 June 2004
• Website: http://www.easternsnow.org/

• International Conference on Groundwater Vulnerability Assessment and Mapping
• Sosnowiec, Poland
• 16–19 June 2004
• Contact: Dr Andrzej J. Witkowski, Secretariat of the Conference, University of Silesia, B?dzińska Str., 60, 41‐200 Sosnowiec, Poland
• Tel: +48 32 291 68 88
• Fax: +48 32 291 58 65
• E‐mail: switkows@us.edu.pl
• Website: http://khgi.wnoz.us.edu.pl/vulnerability.htm

• Riverflow 2004–Second International Conference on Fluvial Hydraulics
• Naples, Italy
• 23–25 June 2004
• Website: http://www.riverflow2004.unina.it

• Riparian Ecosystems and Buffers: Multi‐Scale Structure, Function and Management
• Olympic Valley, CA
• 28–30 June 2004
• Website: http://www.awra.org/Olympic2004/index.html

• BHS International Conference on ‘Hydrology: Science and Practise for the 21^st Century’
• Imperial College, London
• 12–16 July 2004
• Contact: Dr Adrian Butler
• Tel: 020 7954 6122 Fax: 020 7594 6124
• E‐mail: a.butler@ic.ac.uk
• Website: http://www.hydrology.org.uk/index.html

• Italia 2004 32^nd International Geological Congress “From the Mediterranean Area Toward a Global Geological Renaissance” Geology, Natural Hazards and Cultural Heritage
• Florence
• 20–28 August 2004
• Contact: Chiara Manetti, Dipartimento di Scienze della Terra, Via La Pira, 4‐50121 Firenze, Italy
• Tel/Fax: +39 055 2382146
• Email: casaitalia@geo.unifi.it

• Good Water Governance for People & Nature: What Roles for Law, Institutions, Science & Finance
• Dundee, Scotland
• 29 August–1 September 2004
• Website: http://www.awra.org/meetings/Dundee2004/index.html

• XXXIII Congress of IAH—Conference on Groundwater Flow Understanding: From Local to Regional Scale. Joint Conference IAH/ALHSUD
• Mexico
• 11–15 October 2004
• E‐mail: aih@igris.igeograf.unam.mx
• Website: www.igeograf.unam.mx/aih

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

Conference listing

• Hydro4
• Galway, Ireland
• 2–4 November 2004
• Contact: Susan Haley, Hydro4, 74 Callington Road, Saltash, Cornwall, PL12 6DY, UK
• E‐mail: hydro4@hydrographicsociety.org

• 2nd IWA Leading‐Edge Conference on Sustainability in Water‐Limited Environments
• Sydney, Australia
• 8–10 November 2004
• Website: www.les2004.iwa‐conferences.org

• International Association of Hydrological Sciences Scientific Assembly
• Foz do lguaçu, Brazil
• 3–9 April 2005
• Website: www.cig.ensmp.fr/～iahs

• Acid Rain 2005 7th International Conference on Acid Deposition
• Prague, Czech Republic
• 12–17 June 2005
• Contact: Jaroslav Santroch Czech Hydrometeorological Institute, Na Sabatce 17, 14306 Prague 4, Czech Republic
• Tel: +420 24 1765803
• Fax: +420 24 1760689
• E‐mail: info@acidrain2005.cz
• Website: http://www.acidrain2005.cz

• 10th International Symposium on the Interactions between Sediments and Water
• Lake Bled, Slovenia
• 28th August–2nd September 2005
• Website: http://www.wsc.monash.edu.au/iasws/2005symposium.htm

• EnvironmexAsia2
• Singapore
• 29th November–2nd December 2005
• Website: http://www.environmexasia.com

If you would like your conference included please E‐mail details to Anne Flynn. E‐mail: aflynn@wiley.co.uk Copyright © 2004 John Wiley & Sons, Ltd.     

RADON DEPTH MIGRATION1

A depth migration method is presented that uses Radon-transformed common-source seismograms as input. It is shown that the Radon depth migration method can be extended to spatially varying velocity depth models by using asymptotic ray theory (ART) to construct wavefield continuation operators. These operators downward continue an incident receiver-array plane wave and an assumed point-source wavefield into the subsurface. The migration velocity model is constrained to have longer characteristic wavelengths than the dominant source wavelength such that the ART approximations for the continuation operators are valid. This method is used successfully to migrate two synthetic data examples:

• 1 a point diffractor, and
• 2 a dipping layer and syncline interface model.

It is shown that the Radon migration method has a computational advantage over the standard Kirchhoff migration method in that fewer rays are computed in a main memory implementation.