Implementation of an Automatic Polarization S‐Wave Picker for Local Earthquake Relocation and Tomography in South‐Central Tibet

2017 ◽  
Vol 107 (5) ◽  
pp. 2501-2510
Author(s):  
Evan Riddle ◽  
John Nabelek ◽  
Jochen Braunmiller
Keyword(s):  
S Wave ◽  
Earthquake Relocation ◽  
South Central ◽  
Local Earthquake ◽  
Central Tibet

scholarly journals Compilation of a recent seismicity data base of the greater Alpine region from several seismological networks and preliminary 3D tomographic results

1997 ◽  
Vol 40 (1) ◽  
Author(s):  
S. Solarino ◽  
E. Kissling ◽  
S. Sellami ◽  
G. Smriglio ◽  
F. Thouvenot ◽  
...  
Keyword(s):  
Travel Time ◽  
Central Europe ◽  
Alpine Region ◽  
Data Sets ◽  
S Wave ◽  
Data Set ◽  
South Central ◽  
Local Earthquake ◽  
Phase Data ◽  
Master Station

Local earthquake data collected by seven national and regional seismic networks have been compiled into a travel time catalog of 32341 earthquakes for the period 1980 to 1995 in South-Central Europe. As a prerequisite, a complete and corrected station list (master station list) has been prepared according to updated information provided by every network. By simultaneous inversion of some 600 well-locatable events we obtained one-dimensional (1D) velocity propagation models for each network. Consequently, these velocity models with appropriate station corrections have been used to obtain high-quality hypocenter locations for events inside and among the station networks. For better control, merging of phase data from several networks was performed as an iterative process where at each iteration two data sets of neighbouring networks or groups of networks were merged. Particular care was taken to detect and correctly identify phase data from events common to data sets from two different networks. In case of reports of the same phase data from more than one network, the phase data from the network owning and servicing the station were used according to the master station list. The merging yielded a data set of 278007 P and 191074 S-wave travel time observations from 32341 events in the greater Alpine region. Restrictive selection (number of P-wave observations >7; gap <160 degrees) yielded a data set of about 10000 events with a total of more than 128000 P and 87000 S-wave observations well suited for local earthquake seismic tomography study. Preliminary tomographic results for South-Central Europe clearly show the topography of the crust-mantle boundary in the greater Alpine region and outline the 3D structure of the seismic Ivrea body.

Velocity Models for the Crust Hosting the Main Aftershock Cluster of the 2011 Mineral, Virginia, Earthquake

2021 ◽  
Author(s):  
S. M. Ariful Islam ◽  
Christine A. Powell ◽  
Martin C. Chapman
Keyword(s):  
Three Dimensional ◽  
Passive Margin ◽  
Depth Range ◽  
Good Resolution ◽  
S Wave ◽  
Velocity Models ◽  
Taconic Orogeny ◽  
Thrust Sheets ◽  
Local Earthquake ◽  
Virginia Earthquake

Abstract Three-dimensional P- and S-wave velocity (VP and VS) models are determined for the crust containing the main aftershock cluster of the 2011 Mineral, Virginia, earthquake using local earthquake tomography. The inversion uses a total of 5125 arrivals (2465 P- and 2660 S-wave arrivals) for 324 aftershocks recorded by 12 stations. The inversion volume (22 × 20 × 16 km) is completely contained within the Piedmont Chopawamsic metavolcanic terrane. The models are well resolved in the central portion of the inversion volume in the depth range 1–5 km; good resolution does not extend to the hypocenter depth of the mainshock. Most aftershocks are located within a northeast-trending, southeast-dipping region containing negative VP anomalies, positive VS anomalies, and VP/VS ratios as low as 1.53. These velocity results strongly argue for the presence of quartz-rich rocks, which we attribute to either the presence of a giant quartz vein system or metamorphosed orthoquarzite sandstones originally deposited on the Laurentian passive margin and subsequently incorporated into the Chopawamsic thrust sheets during island arc collision in the Taconic orogeny.

scholarly journals The Local Earthquake Tomography of Erzurum (Turkey) Geothermal Area

2019 ◽  
Vol 23 (3) ◽  
pp. 209-223 ◽  
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.

Toward Simultaneous Determination of Bulk Crustal Properties Using Virtual Deep Seismic Sounding

2020 ◽  
Vol 110 (3) ◽  
pp. 1387-1392 ◽  
Author(s):  
Qing Chen ◽  
Wang-Ping Chen
Keyword(s):  
Wave Train ◽  
Silica Content ◽  
P Wave ◽  
Deep Seismic Sounding ◽  
Wide Angle ◽  
Virtual Source ◽  
S Wave ◽  
Large Signal ◽  
Seismic Sounding ◽  
Central Tibet

ABSTRACT We augment the method of virtual deep seismic sounding (VDSS) by adding the phases Sp, the SV-P conversion across the Moho, to determine the average speed of the S wave (VS) in the crust. VDSS uses the strong SV-P conversion below the free surface from teleseismic earthquakes as a virtual source for wide-angle reflections of the P wave. The large signal generated by the virtual source is the strongest aspect of VDSS in which no stacking is necessary to build up the signal. Previous work used the large moveout of the wide-angle reflection, phase SsPmp, relative to the direct S-wave arrival, phase Ss, to minimize the trade-off between bulk P-wave speed (VP) and thickness of the crust (H). It is then straightforward to use the timing of the phase Sp to constrain VS. As examples, we show that this method works for data from both temporary and permanent seismic deployments in contrasting tectonic settings. Specifically, VS under station FORT in western Australia and H1620 in central Tibet are 3.77±0.08 and 3.42±0.11  km/s, respectively. This development complements the undertaking of using information from only the S-wave train to extract all three seismic parameters of the bulk crust, VP, VS, and H. These parameters are important for constraining overall silica content of the crust.

Hydrological and geomorphological basin and catchment characteristics of Lake Nam Co, South-Central Tibet

2010 ◽  
Vol 218 (1-2) ◽  
pp. 118-130 ◽  
Author(s):  
A. Keil ◽  
J. Berking ◽  
I. Mügler ◽  
B. Schütt ◽  
A. Schwalb ◽  
...  
Keyword(s):  
Nam Co ◽  
Catchment Characteristics ◽  
South Central ◽  
Lake Nam Co ◽  
Central Tibet

scholarly journals Out-of-sequence deformation and expansion of the Himalayan orogenic wedge: insight from the Changgo culmination, south-central Tibet

1970 ◽  
Vol 5 (7) ◽  
pp. 84
Author(s):  
Kyle P Larson ◽  
Laurent Godin
Keyword(s):  
Special Issue ◽  
South Central ◽  
Orogenic Wedge ◽  
Central Tibet

DOI = 10.3126/hjs.v5i7.1279 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.84

scholarly journals Out-of-sequence deformation and expansion of the Himalayan orogenic wedge: insight from the Changgo culmination, south central Tibet

Tectonics ◽  
2010 ◽  
Vol 29 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Kyle P. Larson ◽  
Laurent Godin ◽  
William J. Davis ◽  
Don W. Davis
Keyword(s):  
South Central ◽  
Orogenic Wedge ◽  
Central Tibet
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