Q estimation based on the logarithmic spectral area double difference

The Q factor is an essential parameter describing the characteristics of medium absorption within a material during wave propagation. When a seismic wave propagates within the attenuating media, its amplitude decreases and frequency band narrows, resulting in a variation in its logarithmic spectral area. Based on these effects, we calculate the logarithmic spectral area difference (LSAD) before and after attenuation and set a division point to divide the LSAD into two parts. We then compute the difference between the two LSADs to derive a new Q-estimation formula based on computation of the logarithmic spectral area double difference (LSADD). To improve the noise robustness of the Q estimation, we select multiple different division points to calculate the Q factors and consider their average value as our final estimate. We then compare and analyze the noise robustness and bandwidth sensitivity of our technique with other commonly used methods. These results demonstrate that our approach is the most accurate and robust, and least sensitive to the frequency band when processing noisy synthetic seismograms. Finally, we apply our methodology to field vertical seismic profile (VSP) and seismic reflection data, further illustrating the effectiveness of this method to estimate the Q factor.

Download Full-text

Crustal models of the eastern Superior Province, Quebec, derived from new gravity data

Canadian Journal of Earth Sciences ◽

10.1139/e99-080 ◽

2000 ◽

Vol 37 (2-3) ◽

pp. 385-397 ◽

Cited By ~ 7

Author(s):

Hamid Telmat ◽

Jean-Claude Mareschal ◽

Clément Gariépy ◽

Jean David ◽

Caroline N Antonuk

Keyword(s):

Gravity Data ◽

Seismic Profile ◽

Density Variation ◽

Crustal Thickening ◽

Superior Province ◽

Seismic Line ◽

Seismic Reflection Data ◽

The North ◽

Reflection Data ◽

Field Evidence

New gravity data were collected in the Nemiscau and La Grande subprovinces of the Superior Province. This ~350 km gravity profile follows the Matagami-Radisson road and extends northward the gravity transect along the ~260 km long Lithoprobe seismic line 48, across the northern Abitibi and Opatica subprovinces. For the Abitibi-Opatica segment, the interpretation is consistent with the Lithoprobe seismic profile. It calls for crustal thickening near the boundary between the Abitibi and Opatica belts, where the Moho is ~5 km deeper than in the Abitibi subprovince and ~8 km deeper than in the northern Opatica subprovince. The gravity model complements the seismic reflection data and provides information on the uppermost supracrustal sequences poorly imaged in the seismic profile. Most of the intrusive rocks in the Opatica Belt appear as thin (<5 km) bodies. Across the Nemiscau and La Grande subprovinces, the Bouguer anomalies are of short wavelengths and their sources lie in the upper crust. The crustal thickness is constant from the northern Opatica Belt throughout the southern part of the Nemiscau subprovince. Density measurements indicate that the upper crustal density is higher in the Nemiscau and La Grande subprovinces than in the Abitibi and Opatica belts. There is some crustal thickening beneath the La Grande subprovince, and a gravity high at the northern end of the subprovince is related to the occurrence of mafic supracrustal sequences. The gravity anomaly signature associated with the lateral density variation and field evidence indicate that the main tectonic boundaries dip to the north.

Download Full-text

Seismic expression of shallow structures in active tectonic settings in New Zealand

Exploration Geophysics ◽

10.1071/eg989287 ◽

1989 ◽

Vol 20 (2) ◽

pp. 287

Author(s):

C.D. Cape ◽

R.M. O'Connor ◽

J.M. Ravens ◽

D.J. Woodward

Keyword(s):

New Zealand ◽

Plate Boundary ◽

Accretionary Prism ◽

Seismic Profile ◽

Thrust Fault ◽

Strike Slip ◽

Normal Faults ◽

Thrust Faults ◽

Seismic Reflection Data ◽

Reflection Data

Late Cenozoic deformation along the Australian/Pacific plate boundary is seen in onshore New Zealand as zones characterised by extension- or transcurrent- or contraction-related structures. High-resolution multichannel seismic reflection data were acquired in several of these tectonic zones and successfully reveal the shallow structures within them. Thirty kilometres of dynamite reflection data in the Rangitaiki Plains, eastern Bay of Plenty, define a series of NE-trending normal faults within this extensional back-arc volcanic region. The data cross surface ruptures activated during the 1987 Edgecumbe earthquake. In the southern North Island, a 20 km Mini-Sosie? seismic profile details the Quaternary sedimentation history and reveals the structure of the active strike-slip and thrust fault systems that form the western and eastern edges of the Wairarapa basin, respectively. This basin is considered to sit astride the boundary between a zone of distributed strike-slip faults and an active accretionary prism. In the Nelson area, northwestern South Island, previously unrecognised low-angle thrust faults of Neogene or Quaternary age are seen from Mini-Sosie data to occur at very shallow depths. Crustal shortening here was previously thought to arise from movement on high-angle reverse faults, and the identification of these low-angle faults has prompted a reassessment of that model. A grid of 18 km of Mini-Sosie seismic data from the central eastern South Island delineates Neogene or Quaternary thrust faults in Cenozoic sediments. The thrusts are interpreted as reactivated Early Eocene normal faults, and the thrust fault geometry is dominated by these older structures.

Download Full-text

Seismic-Reflection Identification of Susquehanna River Paleochannels on the Mid-Atlantic Coastal Plain

Quaternary Research ◽

10.1006/qres.1994.1066 ◽

1994 ◽

Vol 42 (2) ◽

pp. 166-175 ◽

Cited By ~ 5

Author(s):

Robert B. Genau ◽

John A. Madsen ◽

Susan McGeary ◽

John F. Wehmiller

Keyword(s):

High Resolution ◽

Coastal Plain ◽

Seismic Reflection ◽

River System ◽

High Amplitude ◽

Seismic Profile ◽

Atlantic Coastal Plain ◽

Seismic Reflection Data ◽

Susquehanna River ◽

Reflection Data

AbstractLand-based, high-resolution seismic-reflection methods were used to image Quaternary paleochannels of the Susquehanna River system. Using a portable, 12-channel signal-enhancing seismograph, 12 accelerometers as receivers, and a 4.54-kg sledge hammer struck against an aluminum plate as a source, a sixfold, multichannel seismic profile 2.5 km long was acquired at Taylors Island, Maryland. On the processed seismic profile, pronounced high-amplitude seismic reflections delineate the unconformity between Quaternary and underlying Tertiary sediments and the disconformable contact separating Miocene and Eocene deposits. Subsurface-seismic stratigraphic relationships that clearly indicate the presence of two paleochannels were observed, one believed to be the Exmore paleochannel, projected to underlie northern Taylors Island based on marine seismic data. An overlapping sequence of fill sediments was observed on the eastern margin of the Exmore paleochannel. The second paleochannel may be a tributary of the Exmore or possibly the western edge of the younger Eastville paleochannel. Results from this study indicate that land-based, shallow, high-resolution seismic-reflection data can be used to delineate subsurface geomorphology successfully in coastal plain environments. This technique of defining erosional surfaces and depositional units beneath present land areas, when integrated with chronostratigraphic data, is a powerful tool for developing a better understanding of the Quaternary record.

Download Full-text

Comparison between reprocessed seismic profiles: Seismologic and geologic data — A case study of the Colfiorito earthquake area

Geophysics ◽

10.1190/1.2187709 ◽

2006 ◽

Vol 71 (2) ◽

pp. B29-B40 ◽

Cited By ~ 2

Author(s):

Eusebio Stucchi ◽

Francesco Mirabella ◽

Maria Grazia Ciaccio

Keyword(s):

Seismic Profile ◽

Hydrocarbon Exploration ◽

Normal Faults ◽

Seismic Profiles ◽

Epicentral Area ◽

Seismic Reflection Data ◽

Reflection Data ◽

Marche Region ◽

History Of

Seismic reflection data are used to reconstruct the subsurface geologic structures below the Umbria-Marche region in Italy, a highly seismogenic area with a recent history of seismic activity (the 1997–1998 Colfiorito sequence). We reprocess three vibroseis seismic profiles (acquired in the early 1980s for hydrocarbon exploration) whose stacked sections were optimized for relatively deep oil targets. On the reprocessed seismic profile closest to the epicentral area, we construct the main reflectors to a depth of about 4 s (two-way time) and compare this interpretation with the available hypocenters of the 1997 earthquakes. The improvements in visualizing the shallow and deep reflections provide a better correlation between the reflectors and the observed surface structures as well as a better delineation of the basement-rock geometry. We find that part of the Colfiorito sequence is localized around some of the reflectors in the reflection profile, which we interpret as related to the active normal faults that outcrop at the surface.

Download Full-text

Double-difference elastic-waveform inversion with prior information for time-lapse monitoring

Geophysics ◽

10.1190/geo2012-0527.1 ◽

2013 ◽

Vol 78 (6) ◽

pp. R259-R273 ◽

Cited By ~ 25

Author(s):

Zhigang Zhang ◽

Lianjie Huang

Keyword(s):

Oil Recovery ◽

Prior Information ◽

Waveform Inversion ◽

Time Lapse ◽

Double Difference ◽

Enhanced Geothermal Systems ◽

Geothermal Systems ◽

Reservoir Properties ◽

Seismic Reflection Data ◽

Reflection Data

Quantitative time-lapse seismic monitoring can provide crucial information for enhanced oil recovery, geologic carbon storage, and enhanced geothermal systems. Recently developed double-difference elastic-waveform inversion has the potential to quantitatively monitor reservoirs using seismic reflection data. Because the approximate location of a reservoir or a target monitoring region is usually known, we incorporated this knowledge as prior information into double-difference elastic-waveform inversion. Using numerical examples of synthetic time-lapse models, we found that our new method can quantitatively monitor the changes of elastic properties within reservoirs. Therefore, the double-difference elastic-waveform inversion with prior information on the location of a monitoring region is a promising tool for quantitatively monitoring reservoir properties’ changes.

Download Full-text