THE DETERMINATION OF CRUSTAL THICKNESS FROM THE SPECTRUM OF P WAVES

1965 ◽  
Author(s):  
Luis M. Fernandez
Keyword(s):  
Crustal Thickness ◽  
P Waves

An observational determination of the variation of the angle of incidence of P waves with epicentral distance

1961 ◽  
Vol 51 (2) ◽  
pp. 269-276
Author(s):  
Otto Nuttli ◽  
John D. Whitmore
Keyword(s):  
Epicentral Distance ◽  
Crustal Thickness ◽  
Earth’S Crust ◽  
P Wave ◽  
Angle Of Incidence ◽  
P Waves ◽  
Wave Data ◽  
Earth's Crust ◽  
Alaska Earthquake

Abstract Apparent angles of incidence of the P wave were obtained from the seismograms of the Galitzin-Wilip instruments at Florissant. The “half-periods” of these waves varied from 112 to 312 seconds, and the epicentral distances from 16.5° to 103.2°. The data indicate that the velocity of P waves at the earth's surface is approximately 8 km/sec. This suggests that these P waves do not see or are not affected by the earth's crust, although the crustal thickness is known to be approximately 35 km. P wave data from five other stations for the Alaska earthquake of July, 1958 support the conclusions obtained from the Florissant data.

Near earthquakes in Central California*

1939 ◽  
Vol 29 (3) ◽  
pp. 427-462 ◽  
Author(s):  
Perry Byerly
Keyword(s):  
Least Squares ◽  
Travel Time ◽  
Sierra Nevada ◽  
Accurate Determination ◽  
Depth Of Focus ◽  
Surface Layers ◽  
P Waves ◽  
Central California ◽  
The Waves

Summary Least-squares adjustments of observations of waves of the P groups at central and southern California stations are used to obtain the speeds of various waves. Only observations made to tenths of a second are used. It is assumed that the waves have a common velocity for all earthquakes. But the time intercepts of the travel-time curves are allowed to be different for different shocks. The speed of P̄ is found to be 5.61 km/sec.±0.05. The speed for S̄ (founded on fewer data) is 3.26 km/sec. ± 0.09. There are slight differences in the epicenters located by the use of P̄ and S̄ which may or may not be significant. It is suggested that P̄ and S̄ may be released from different foci. The speed of Pn, the wave in the top of the mantle, is 8.02 km/sec. ± 0.05. Intermediate P waves of speeds 6.72 km/sec. ± 0.02 and 7.24 km/sec. ± 0.04 are observed. Only the former has a time intercept which allows a consistent computation of structure when considered a layer wave. For the Berkeley earthquake of March 8, 1937, the accurate determination of depth of focus was possible. This enabled a determination of layering of the earth's crust. The result was about 9 km. of granite over 23 km. of a medium of speed 6.72 km/sec. Underneath these two layers is the mantle of speed 8.02 km/sec. The data from other shocks centering south of Berkeley would not fit this structure, but an assumption of the thickening of the granite southerly brought all into agreement. The earthquakes discussed show a lag of Pn as it passes under the Sierra Nevada. This has been observed before. A reconsideration of the Pn data of the Nevada earthquake of December 20, 1932, together with the data mentioned above, leads to the conclusion that the root of the mountain mass projects into the mantle beneath the surface layers by an amount between 6 and 41 km.

Seismic analysis of the 7 January 1998 Chemical plant explosion at Kean Canyon, Nevada

1999 ◽  
Vol 89 (4) ◽  
pp. 938-945 ◽  
Author(s):  
Gene A. Ichinose ◽  
Kenneth D. Smith ◽  
John G. Anderson
Keyword(s):  
Seismic Analysis ◽  
Correlation Method ◽  
Chemical Safety ◽  
P Waves ◽  
Arrival Times ◽  
Chemical Company ◽  
Optimal Separation ◽  
The Difference ◽  
Possible Cause

Abstract An accident at the Sierra Chemical Company Kean Canyon plant, 16 km east of Reno, Nevada, resulted in two explosions 3.52 sec apart that devastated the facility. An investigation into a possible cause for the accident required the determination of the chronological order of the explosions. We resolved the high-precision relative locations and chronology of the explosions using a cross-correlation method applied to both seismic and air waves. The difference in relative arrival times of air waves between the explosions indicated that the first explosion occurred at the northern site. We then determined two station centroid separations between explosions, which average about 73 m with uncertainties ranging from ± 17 to 41 m depending on the alignment of station pairs. We estimated a centroid separation of 80 m using P waves with a larger uncertainty of ± 340 m. We performed a grid search for an optimal separation and the azimuth by combining air-wave arrivals from three station pairs. The best solution for the relative location of the second explosion is 73.2 m S35°E from the first explosion. This estimate is well within the uncertainties of the survey by the U.S. Chemical Safety and Hazard Investigation Board (CSB). The CSB reported a separation of approximately 76.2 m S33°E. The spectral amplitudes of P waves are 3 to 4 times higher for the second explosion relative to the first explosion, but the air waves have similar spectral amplitudes. We suggest that this difference is due to the partitioning of energy between the ground and air caused by downward directivity at the southern explosion, and upward directivity at the northern explosion. This is consistent with the absence of a crater for the first explosion and a 1.8-m-deep crater for the second explosion.

Determination of crustal thickness and velocities by using receiver functions andPmPtravel times

2018 ◽  
Vol 216 (2) ◽  
pp. 1304-1312 ◽  
Author(s):  
Song Luo ◽  
Lupei Zhu ◽  
Rong Huang ◽  
Yinhe Luo ◽  
Xiaohuan Jiang ◽  
...  
Keyword(s):  
Crustal Thickness ◽  
Receiver Functions

Rapid Determination of Earthquake Magnitude Using Measurements of the Dominant Period of P-Waves Observed at Local Stations in North Sulawesi

2017 ◽  
Vol 23 (12) ◽  
pp. 12064-12067 ◽  
Author(s):  
Tjipto Prastowo ◽  
DyahAyu Puspitasari ◽  
La Ode Ngkoimani ◽  
La Ode Safiuddin
Keyword(s):  
Rapid Determination ◽  
Earthquake Magnitude ◽  
P Waves ◽  
North Sulawesi ◽  
Dominant Period

scholarly journals Determination of crustal thickness beneath Chiapas, Mexico usingSandSpwaves

2004 ◽  
Vol 157 (1) ◽  
pp. 215-228 ◽  
Author(s):  
C. Narcía-López ◽  
R. R. Castro ◽  
C. J. Rebollar
Keyword(s):  
Crustal Thickness

scholarly journals Determination of Temperature on Ice Caps by Seismic Methods

1968 ◽  
Vol 7 (50) ◽  
pp. 333-335 ◽  
Author(s):  
F. Thyssen
Keyword(s):  
Empirical Formula ◽  
Temperature Measurements ◽  
Seismic Velocities ◽  
P Waves ◽  
Ice Caps ◽  
Seismic Methods ◽  
The Mean

An empirical formula, derived by the author for the seismic velocities of P waves in glaciers and ice caps, is used to determine the temperatures which can be deduced from the maximum and the mean vertical velocities. With the aid of several examples from previous publications, these temperatures are discussed and, as far as they are available, direct temperature measurements are compared with the derived temperatures.

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