Three Dimensional Crustal P‐wave Structure beneath the Central South Segment of the Tanlu Fault Zone Determined by Local Earthquake Travel‐time Tomography

Three-dimensional P wave velocity models under the Zipingpu reservoir in Longmenshan fault zone are obtained with a resolution of 2 km in the horizontal direction and 1 km in depth. We used a total of 8589 P wave arrival times from 1014 local earthquakes recorded by both the Zipingpu reservoir network and temporary stations deployed in the area. The 3-D velocity images at shallow depth show the low-velocity regions have strong correlation with the surface trace of the Zipingpu reservoir. According to the extension of those low-velocity regions, the infiltration depth directly from the Zipingpu reservoir itself is limited to 3.5 km depth, while the infiltration depth downwards along the Beichuan-Yingxiu fault in the study area is about 5.5 km depth. Results show the low-velocity region in the east part of the study area is related to the Proterozoic sedimentary rocks. The Guanxian-Anxian fault is well delineated by obvious velocity contrast and may mark the border between the Tibetan Plateau in the west and the Sichuan basin in the east.

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Three-Dimensional Acoustic Travel-Time Tomography of the Atmosphere

Acta Acustica united with Acustica ◽

10.3813/aaa.918042 ◽

2008 ◽

Vol 94 (3) ◽

pp. 349-358 ◽

Cited By ~ 13

Author(s):

Sergey N. Vecherin ◽

Vladimir E. Ostashev ◽

Keith D. Wilson

Keyword(s):

Travel Time ◽

Three Dimensional ◽

Travel Time Tomography ◽

Acoustic Travel Time

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Full waveform inversion of short-offset, band-limited seismic data inthe Alboran basin (SE Iberia)

10.5194/se-2019-46 ◽

2019 ◽

Author(s):

Clàudia Gras ◽

Valentí Sallarès ◽

Daniel Dagnino ◽

C. Estela Jiménez ◽

Adrià Meléndez ◽

...

Keyword(s):

Travel Time ◽

Seismic Data ◽

Waveform Inversion ◽

Velocity Model ◽

P Wave ◽

Full Waveform Inversion ◽

Time Inversion ◽

Full Waveform ◽

Travel Time Tomography ◽

Band Limited

Abstract. We present a high-resolution P-wave velocity model of the sedimentary cover and the uppermost basement until ~ 3 km depth obtained by full-waveform inversion of multichannel seismic data acquired with a 6 km-long streamer in the Alboran Sea (SE Iberia). The inherent non-linearity of the method, especially for short-offset, band-limited seismic data as this one, is circumvented by applying a data processing/modeling sequence consisting of three steps: (1) data re-datuming by back-propagation of the recorded seismograms to the seafloor; (2) joint refraction and reflection travel-time tomography combining the original and the re-datumed shot gathers; and (3) FWI of the original shot gathers using the model obtained by travel-time tomography as initial reference. The final velocity model shows a number of geological structures that cannot be identified in the travel-time tomography models or easily interpreted from seismic reflection images alone. A sharp strong velocity contrast accurately defines the geometry of the top of the basement. Several low-velocity zones that may correspond to the abrupt velocity change across steeply dipping normal faults are observed at the flanks of the basin. A 200–300 m thick, high-velocity layer embedded within lower velocity sediment may correspond to evaporites deposited during the Messinian crisis. The results confirm that the combination of data re-datuming and joint refraction and reflection travel-time inversion provides reference models that are accurate enough to apply full-waveform inversion to relatively short offset streamer data in deep water settings starting at field-data standard low frequency content of 6 Hz.

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The Local Earthquake Tomography of Erzurum (Turkey) Geothermal Area

Earth Sciences Research Journal ◽

10.15446/esrj.v23n3.74921 ◽

2019 ◽

Vol 23 (3) ◽

pp. 209-223 ◽

Cited By ~ 2

Author(s):

Caglar Ozer ◽

Mehmet Ozyazicioglu

Keyword(s):

Wave Velocity ◽

Seismic Velocity ◽

Three Dimensional ◽

P Wave ◽

Geothermal Area ◽

S Wave ◽

Velocity Models ◽

Local Earthquake Tomography ◽

P Wave Velocity ◽

Local Earthquake

Erzurum and its surroundings are one of the seismically active and hydrothermal areas in the Eastern part of Turkey. This study is the first approach to characterize the crust by seismic features by using the local earthquake tomography method. The earthquake source location and the three dimensional seismic velocity structures are solved simultaneously by an iterative tomographic algorithm, LOTOS-12. Data from a combined permanent network comprising comprises of 59 seismometers which was installed by Ataturk University-Earthquake Research Center and Earthquake Department of the Disaster and Emergency Management Authority to monitor the seismic activity in the Eastern Anatolia, In this paper, three-dimensional Vp and Vp/Vs characteristics of Erzurum geothermal area were investigated down to 30 km by using 1685 well-located earthquakes with 29.894 arrival times, consisting of 17.298 P- wave and 12.596 S- wave arrivals. We develop new high-resolution depth-cross sections through Erzurum and its surroundings to provide the subsurface geological structure of seismogenic layers and geothermal areas. We applied various size horizontal and vertical checkerboard resolution tests to determine the quality of our inversion process. The basin models are traceable down to 3 km depth, in terms of P-wave velocity models. The higher P-wave velocity areas in surface layers are related to the metamorphic and magmatic compact materials. We report that the low Vp and high Vp/Vs values are observed in Yedisu, Kaynarpinar, Askale, Cimenozu, Kaplica, Ovacik, Yigitler, E part of Icmeler, Koprukoy, Uzunahmet, Budakli, Soylemez, Koprukoy, Gunduzu, Karayazi, Icmesu, E part of Horasan and Kaynak regions indicated geothermal reservoir.

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