Tomographic Pn Velocity and Anisotropy Structure in Mongolia and the Adjacent Regions

2019 ◽  
Vol 124 (4) ◽  
pp. 3662-3679 ◽  
Author(s):  
Jing He ◽  
Yonghua Li ◽  
Eric Sandvol ◽  
Qingju Wu ◽  
Guangbao Du ◽  
...  
Keyword(s):  
Pn Velocity

Crustal structure of the southeast flank of Kilauea Volcano, Hawaii, from seismic refraction measurements

1980 ◽  
Vol 70 (4) ◽  
pp. 1149-1159
Author(s):  
John J. Zucca ◽  
David P. Hill
Keyword(s):  
Oceanic Crust ◽  
Crustal Structure ◽  
Seismic Refraction ◽  
Kilauea Volcano ◽  
Geological Survey ◽  
Pn Velocity ◽  
Kīlauea Volcano ◽  
Volcanic Pile ◽  
Rift Zones ◽  
The U.S

abstract In November 1976, the U.S. Geological Survey, in conjunction with the Hawaii Institute of Geophysics, established a 100-km-long seismic refraction line normal to the southeast coast of Hawaii across the submarine flank of Kilauea Volcano. Interpretation of the data suggests that the oceanic crust dips about 2° toward the island underneath the volcanic pile. The unreversed Pn velocity is 7.9 km/ sec with crustal velocities varying strongly along the profile. Profiles across the rift zones of Kilauea suggest that the velocity in the rifts is higher than the velocity in the surrounding extrusive rocks and that the velocity in the southwest rift (∼6.5 km/sec) is lower than the velocity in the east rift (∼7.0 km/sec). The rift boundaries seem to dip away from the rift such that a large part of the volcanic pile is composed of the higher velocity core of riftzone rock.

scholarly journals Effect of ambient wind velocity on Planetary Nebula morphology

1997 ◽  
Vol 180 ◽  
pp. 224-224
Author(s):  
Vikram V. Dwarkadas ◽  
Roger A. Chevalier ◽  
John M. Blondin
Keyword(s):  
Wind Velocity ◽  
Ambient Medium ◽  
Asymptotic Giant Branch ◽  
Density Contrast ◽  
Expansion Velocity ◽  
Ambient Wind ◽  
Pn Velocity ◽  
Fast Wind ◽  
Self Similar ◽  
Slow Wind

Planetary Nebulae (PNe) are formed by the interaction of the fast wind from a post-Asymptotic Giant Branch Star with the slow ambient wind from a previous epoch. If the two interacting winds have constant properties, the velocity of the PN shell tends towards a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNe in the self-similar stage (Dwarkadas et al. 1996). We have investigated the contribution of the ambient wind velocity to PN morphology, which has hitherto not received much attention since the work of Kahn & West (1985). We find that the nebular morphology is a consequence of the density contrast between pole and equator in the ambient medium, the steepness of the density profile and the velocity of the ambient wind; classification of PNe purely on the basis of the first two factors may be misleading. In particular, the ratio of ambient wind velocity to PN velocity is important in determining whether the nebula shows a bulge or a cusp at the equator. A high density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. As long as the external wind velocity is small compared to the expansion velocity of the nebula, the PNe tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, inclusion of an asymmetric velocity profile in the slow wind, with the velocity increasing towards the pole, can lead to a bipolar nebula if the equatorial velocity is sufficiently low. Preliminary results with a slow wind velocity increasing towards the equator (as is found in calculations of common envelope evolution) show that the nebulae tend to be more oblate, which is not often observed in nature. Representative results for shapes of PNe using various values of the relevant parameters are presented.

Pn Velocity in Kyushu Deduced from Travel Time Analysis of Local Earthquakes

1997 ◽  
Vol 50 (3) ◽  
pp. 353-356
Author(s):  
Shuichiro FUKUMITSU ◽  
Hiroki MIYAMACHI ◽  
Toshiki KAKUTA ◽  
Kazuhiko GOTO ◽  
Kodo UMAKOSHI ◽  
...  
Keyword(s):  
Travel Time ◽  
Time Analysis ◽  
Local Earthquakes ◽  
Pn Velocity

Pn Velocity Tomography in Xinjiang, China and Adjacent Regions

2002 ◽  
Vol 45 (2) ◽  
pp. 217-224 ◽  
Author(s):  
Shun-Ping PEI ◽  
Zhong-Huai XU ◽  
Su-Yun WANG ◽  
Thomas M. Hearn
Keyword(s):  
Pn Velocity ◽  
Velocity Tomography

Discussion on origin of Pn velocity variation in China and adjacent region

2004 ◽  
Vol 17 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Shun-ping Pei ◽  
Zhong-huai Xu ◽  
Su-yun Wang
Keyword(s):  
Velocity Variation ◽  
Adjacent Region ◽  
Pn Velocity
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