Regionalization and calibration of seismic discriminants, path effects and signal-to-noise for station ABKT (Alibek, Turkmenistan)
Conference
·
OSTI ID:574693
We report measurements and analysis of regional seismic phase amplitude ratios and signal-to-noise for earthquakes observed at the International Monitoring System primary station ABKT (Alibek, Turkmenistan). We measured noise and phase amplitudes of the regional phases Pn, Pg, Sn, and Lg in four frequency bands between 0.75-9.0 Hz. Measurements were made in both the time and frequency domains. The spatial variation of amplitude ratios (e.g., Pn/Lg, Pg/Lg, Pn/Sn, Pg/Sn) and signal-to-noise (phase/noise) reveal significant path effect differences between the Hindu Kush, Kazahk Platform, Iranian Plateau and Caspian Sea. In order to represent this behavior, we have investigated several techniques for characterizing the data. These techniques are: 1) correlation with along-path distance and waveguide properties; 2) sector analysis; and 3) spatial averaging. Along-path waveguide properties, such as mean elevation and rms topographic slope are found to be the strongest factors related to Pg/Lg amplitude ratios at the lowest frequencies (<3.0 Hz). Other path properties such as mean crustal thickness and basement depth are not strongly correlated with Pg/Lg ratios. For sector analysis we divided the data into four (4) azimuthal sectors and characterized the data within each sector by a distance trend. Sectors were chosen based on the behavior of Pn/Lg, Pg/Lg and Pn/Sn amplitude ratios as well as topographic and tectonic character. Results reveal significant reduction (up to a factor of two) in the scatter of the Pn/Lg and Pg/Lg amplitude ratios for the sectorized data compared to the entire data set from all azimuths. Spatial averaging involves smoothing and interpolation for the ratios projected at the event location. Methods such as cap averaging and kriging will be presented at the meeting. 7 refs., 6 figs.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 574693
- Report Number(s):
- UCRL-JC--127896; CONF-970967--; ON: DE98052178; BR: GC0402000
- Country of Publication:
- United States
- Language:
- English
Similar Records
Representing regional P/S discriminants for event indentification: a comparison of distance corrections, path parameter regressions, cap-averaging and kriging
Comparative study of regional phases from underground nuclear explosions at East Kazakh and Nevada Test Sites. Rept. for Mar 89-Feb 90
Source and Path Effects on Regional Phases in China
Conference
·
Thu Jun 18 00:00:00 EDT 1998
·
OSTI ID:2462
Comparative study of regional phases from underground nuclear explosions at East Kazakh and Nevada Test Sites. Rept. for Mar 89-Feb 90
Technical Report
·
Sat Sep 01 00:00:00 EDT 1990
·
OSTI ID:5806156
Source and Path Effects on Regional Phases in China
Conference
·
Tue Dec 30 23:00:00 EST 1997
·
OSTI ID:655254