scholarly journals Three‐dimensional seismic structure of a Mid‐Atlantic Ridge segment characterized by active detachment faulting (Trans‐Atlantic Geotraverse, 25°55′N‐26°20′N)

2012 ◽  
Vol 13 (11) ◽  
Author(s):  
Minghui Zhao ◽  
Juan Pablo Canales ◽  
Robert A. Sohn
Keyword(s):  
Three Dimensional ◽  
Seismic Structure ◽  
Mid Atlantic Ridge ◽  
Detachment Faulting

scholarly journals Characteristics of relocated hypocenters of the 2018 M6.7 Hokkaido Eastern Iburi earthquake and its aftershocks with a three-dimensional seismic velocity structure

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Saeko Kita
Keyword(s):  
Seismic Velocity ◽  
Three Dimensional ◽  
Double Difference ◽  
Earthquake Catalog ◽  
Seismic Structure ◽  
Depth Limit ◽  
High Attenuation ◽  
South Central ◽  
Collision Zone ◽  
Hidaka Collision Zone

AbstractI relocated the hypocenters of the 2018 M6.7 Hokkaido Eastern Iburi earthquake and its surrounding area, using a three-dimensional seismic structure, the double-difference relocation method, and the JMA earthquake catalog. After relocation, the focal depth of the mainshock became 35.4 km. As previous studies show, in south-central Hokkaido, the Hidaka collision zone is formed, and anomalous deep and thickened forearc crust material is subducting at depths of less than 70 km. The mainshock and its aftershocks are located at depths of approximately 10 to 40 km within the lower crust of the anomalous deep and thickened curst near the uppermost mantle material intrusions in the northwestern edge of this Hidaka collision zone. Like the two previous large events, the aftershocks of this event incline steeply eastward and appear to be distributed in the deeper extension of the Ishikari-teichi-toen fault zone. The highly inclined fault in the present study is consistent with a fault model by a geodetic analysis with InSAR. The aftershocks at depths of 10 to 20 km are located at the western edge of the high-attenuation (low-Qp) zone. These kinds of relationships between hypocenters and materials are the same as the 1970 and 1982 events in the Hidaka collision zone. The anomalous large focal depths of these large events compared with the average depth limit of inland earthquakes in Japan could be caused by the locally lower temperature in south-central Hokkaido. This event is one of the approximately M7 large inland earthquakes that occurred repeatedly at a recurrence interval of approximately 40 years and is important in the collision process in the Hidaka collision zone.

scholarly journals Seismic Structure of Local Crustal Earthquakes beneath the Zipingpu Reservoir of Longmenshan Fault Zone

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Haiou Li ◽  
Xiwei Xu ◽  
Wentao Ma ◽  
Ronghua Xie ◽  
Jingli Yuan ◽  
...  
Keyword(s):  
Fault Zone ◽  
Three Dimensional ◽  
P Wave ◽  
The Tibetan Plateau ◽  
Seismic Structure ◽  
Infiltration Depth ◽  
Low Velocity ◽  
Longmenshan Fault Zone ◽  
Velocity Models ◽  
Longmenshan Fault

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.

Three-dimensional seismic structure of the lithosphere under Montana Lasa

1976 ◽  
Vol 66 (2) ◽  
pp. 501-524
Author(s):  
Keiiti Aki ◽  
Anders Christoffersson ◽  
Eystein S. Husebye
Keyword(s):  
Generalized Inverse ◽  
Random Medium ◽  
Three Dimensional ◽  
P Wave ◽  
Seismic Structure ◽  
Low Velocity ◽  
Medium Theory ◽  
Velocity Anomaly ◽  
Inversion Techniques ◽  
Teleseismic Events

abstract Using P-wave residuals for teleseismic events observed at the Montana Large Aperture Seismic Array (LASA), we have determined the three-dimensional seismic structure of the lithosphere under the array to a depth of 140 km. The root-mean-square velocity fluctuation was found to be at least 3.2 per cent which may be compared to estimate of ca. 2 per cent based on the Chernov random medium theory. The solutions are given by both the generalized inverse and stochastic inverse methods in order to demonstrate the relative merit of different inversion techniques. The most conspicuous feature of the lithosphere under LASA is a low-velocity anomaly in the central and northeast part of the array siting area with the N60°E trend and persisting from the upper crust to depths greater than 100 km. We interpret this low-velocity anomaly as a zone of weakness caused by faulting and shearing associated with the building of the Rocky Mountains.

scholarly journals Seismic structure of an oceanic core complex at the Mid-Atlantic Ridge, 22°19′N

2010 ◽  
Vol 115 (B7) ◽  
Author(s):  
Anke Dannowski ◽  
Ingo Grevemeyer ◽  
Cesar R. Ranero ◽  
Georges Ceuleneer ◽  
Marcia Maia ◽  
...  
Keyword(s):  
Seismic Structure ◽  
Core Complex ◽  
Oceanic Core Complex ◽  
Mid Atlantic Ridge

scholarly journals Three-dimensional geometry of axial magma chamber roof and faults at Lucky Strike volcano on the Mid-Atlantic Ridge

2015 ◽  
Vol 120 (8) ◽  
pp. 5379-5400 ◽  
Author(s):  
Violaine Combier ◽  
Tim Seher ◽  
Satish C. Singh ◽  
Wayne C. Crawford ◽  
Mathilde Cannat ◽  
...  
Keyword(s):  
Magma Chamber ◽  
Three Dimensional ◽  
Lucky Strike ◽  
Mid Atlantic Ridge ◽  
Axial Magma Chamber
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