Seismic Velocities From Surface Measurements

Dix, C. H.

doi:10.1190/1.1438126

Cited by 1,206 publications

(646 citation statements)

References 2 publications

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“…As the profiling offset (distance between antenna centres) is usually much smaller than the ice thickness, the NMO correction will typically affect only the shallowest parts of the profiles. Thus, the use of a flat reflector NMO correction should be sufficient (Dix, 1955;Yilmaz, 2001):…”

Section: Error In the Value Of Ice Thicknessmentioning

confidence: 99%

On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

et al. 2016

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ABSTRACT. This is the first (Paper I) of three companion papers focused respectively, on the estimates of the errors in ice thickness retrieved from pulsed ground-penetrating radar (GPR) data, on how to estimate the errors at the grid points of an ice-thickness DEM, and on how the latter errors, plus the boundary delineation errors, affect the ice-volume estimates. We here present a comprehensive analysis of the various errors involved in the computation of ice thickness from pulsed GPR data, assuming they have been properly migrated. We split the ice-thickness error into independent components that can be estimated separately. We consider, among others, the effects of the errors in radio-wave velocity and timing. A novel aspect is the estimate of the error in thickness due to the uncertainty in horizontal positioning of the GPR measurements, based on the local thickness gradient. Another novel contribution is the estimate of the horizontal positioning error of the GPR measurements due to the velocity of the GPR system while profiling, and the periods of GPS refreshing and GPR triggering. Their effects are particularly important for airborne profiling. We illustrate our methodology through a case study of Werenskioldbreen, Svalbard.

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Section: Error In the Value Of Ice Thicknessmentioning

confidence: 99%

On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

et al. 2016

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“…Os tempos de percurso das reflexões registradas dentro da janela de afastamentos fonte-receptor utilizada estão fora da validade da aproximação hiperbólica (Dix, 1955), convencionalmente empregada para a análise de velocidades. Além disso, o sinal refletido apresenta uma defasagem na sua forma de onda, devidoà reflexão ocorrer acima doângulo crítico de incidência, o que também afeta o processo de análise de velocidades.…”

Section: Reflexão Rasaunclassified

Investigações geofísicas de superfície e de poço no sítio controlado de geofísica rasa do IAG-USP

Porsani

Borges²,

Elis³

et al. 2004

Rev. Bras. Geof.

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ABSTRACT. This paper presents the results obtained from surface and borehole geophysical investigations carried out at the Shallow Geophysical Test Site of IAG-USP. The main objective was to characterize the sediments and the top of basement. The area is constituted by sandy-clay sediments of São Paulo Basin (São Paulo and Resend Formations) on the granite-gneiss basement with different degrees of weathering. In the area of studies, three boreholes were drilled for geological and geophysical research purposes (pioneer in Brazil). These boreholes were used to verify the stratigraphy, to collect the sample for laboratory measurements, to calibrate the results of surface geophysics and to carry out well logging. The surface methods used were: seismic (reflection and refraction), electric-resistivity (profiling and RESUMO. Este trabalho sintetiza os resultados de investigações geofísicas de superfície e de poço realizadas no Sítio Controlado de Geofísica Rasa do IAG-USP,visando caracterizar os sedimentos e o topo do embasamento. Aáreaé constituída por sedimentos areno-argilosos da Bacia de São Paulo (Formações São Paulo e Resende) sobrepostos ao embasamento granito-gnáissico com diferentes graus de intemperização. Naárea de estudos, também denominada de campo de provas do IAG, foram perfurados três poços para pesquisas geológicas e geofísicas (pioneiros no Brasil), visando verificar a litoestratigrafia, coleta de amostras de calha, calibrar os resultados e realizar as perfilagens geofísicas. Foram utilizados os seguintes métodos: sísmica rasa (reflexão e refração), eletrorresistividade (caminhamento elétrico e sondagem elétrica vertical) e GPR-Ground Penetrating Radar. A integração dos resultados mostrou uma excelente concordância e permitiu elaborar um modelo geológico-geofísico para este ponto da Bacia Sedimentar de São Paulo, bem como testar, em condições controladas de campo, os diversos métodos geofísicos usados rotineiramente em estudos geológicos, geotécnicos e ambientais.

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“…Meritve je izvedel Geološki zavod Ljubljana v letih 1952-1955(Urh, 1956. Osi antiformnih oblik na karti se dobro ujemajo z maksimumi Bouguerjevih anomalij, osi sinformnih oblik pa kažejo odstopanje od njihovih minimumov (si.…”

Section: Struktura Predterciame Podlageunclassified

Modelling of seismic reflection data for underground gas storage in the Pečarovci and Dankovci structures - Mura Depression

Gosar¹

1995

Geologija

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Kratka vsebinaAntiformni strukturi Pečarovci in Dankovci v Murski depresiji sta bili izbrani kot najprimernejši v Sloveniji za gradnjo podzemnega skladišča plina v vodonosniku. Da bi dokazali velikost in zaprtost struktur, je bilo posnetih 17 refleksijskih seizmičnih profilov v skupni dolžini 157km in izvrtane so bile tri vrtine. S programom Sierra Mimic je bil izdelan strukturni model dveh interpretiranih horizontov (mezozojska podlaga terciarnih kamnin in meja badenij-sarmatij). Vrednotenje različnih hitrostnih podatkov (analiza hitrosti, akustična karotaža, meritve seizmičnih hitrosti v vrtinah in laboratorijsko na jedrih) je omogočilo natančno spremembo časa v globino ter ugotovitev bočnih sprememb hitrosti. Primerjava ročno in računalniško konstruiranih kart je pokazala dobro ujemanje, z nekoliko večjim odstopanjem le na SE strani strukture Pečarovci. Porozno plast predstavlja v tej strukturi 70m debela plast dolomita v globini 1900m, neprepustno krovnino pa več sto metrov debele plasti laporja. Struktura Dankovci v globini 1200m, kjer predstavljajo ustrezne porozne kamnine tanke plasti konglomerata in pešče-njaka, je bila zaradi prelomov ocenjena za manj primerno. Z ID sintetičnimi seizmogrami je bila opravljena korelacija geoloških in seizmičnih podatkov v vrtinah, posebno na intervalih s tankimi plastmi. Metoda sledenja žarkov na 2D modelih (programski paket Sierra Quik) je bila uporabljena za ugotavljanje zveznosti nekaterih horizontov in za ugotavljanje obstoja prelomov, ki so pomemben dejavnik za skladiščenje plina. AbstractTwo antiform structures in the Mura Depression were selected as the most promising in Slovenia for the construction of an underground gas storage facility in an aquifer. Seventeen reflection lines with a total length of 157km were recorded, and three boreholes were drilled. Structural models corresponding to two different horizons (the pre-Tertiary basement and the Badenian-Sarmatian boundary) were constructed using the Sierra Mimic program. Evaluation of different velocity data (velocity analysis, sonic log, the down-hole method, and laboratory measurements on cores) was carried out in order to perform correct timeto-depth conversion and to estabUsh lateral velocity variations. The porous rock

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Seismic Velocities From Surface Measurements

Cited by 1,206 publications

References 2 publications

On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

Investigações geofísicas de superfície e de poço no sítio controlado de geofísica rasa do IAG-USP

Modelling of seismic reflection data for underground gas storage in the Pečarovci and Dankovci structures - Mura Depression

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