| Autor: |
T. M. Hopson, Paul A. Johnson, T. J. Shankland |
| Rok vydání: |
1993 |
| Předmět: |
|
| Zdroj: |
Geophysical Research Letters. 20:391-394 |
| ISSN: |
0094-8276 |
| DOI: |
10.1029/92gl02758 |
| Popis: |
Using measurements in the frequency domain the authors have measured quality factor Q and travel times of direct and side-reflected elastic waves in a 1.8 m long sample of Berea sandstone. The frequency domain travel rime (FDTT) method produces the continuous-wave (cw) response of a propagating wave by stepwise sweeping frequency of a driving source and detecting amplitude and phase of the received signal in reference to the source. Each separate travel path yields a characteristic repetition cycle in frequency space as its wave vector-distance product is stepped; an inverse fast Fourier transform (IFFT) reveals the corresponding travel time at the group velocity. Because arrival times of direct and reflected elastic waves appear as spikes along the time axis, travel times can be obtained precisely, and different arrivals can be clearly separated. Q can be determined from the amplitude vs. frequency response of each peak as obtained from a moving window IFFT of the frequency-domain signal. In this sample at ambient conditions compressional velocity V[sub P] is 2380 m/s and Q[sub P] is 55. 15 refs., 4 figs. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
Plný text