Papers on Seismology
Anomalous surface waves from Lop Nor nuclear explosions: Observations and numerical modeling
Article first published online: 20 SEP 2012
Copyright 1998 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 103, Issue B7, pages 15051–15068, 10 July 1998
How to Cite
1998), Anomalous surface waves from Lop Nor nuclear explosions: Observations and numerical modeling, J. Geophys. Res., 103(B7), 15051–15068, doi:10.1029/98JB00027., , and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 26 DEC 1997
- Manuscript Received: 14 MAR 1997
Surface waves from the Chinese test site of Lop Nor are analyzed using long-period and broadband stations located at regional and teleseismic distances and at different azimuths. For most azimuths, strong Love waves between 0.02 and 0.045 Hz are observed with an amplitude of up to 10 times that of the Rayleigh waves. In addition, an anomalous early Rayleigh wave train is observed at some stations in western Europe. Due to a particularly favorable station and source configuration, it is possible to isolate the areas where the anomalies are created. The high-amplitude Love waves must be attributed to either source effects or path effects immediately north of Lop Nor. The early wave train is shown to be due to a partial energy conversion between Love and Rayleigh waves, probably at the Tornquist Zone. To estimate the possible contribution from surface wave conversions to the observed anomalies, numerical simulations are carried out with the indirect boundary element method. The simulations show that a relatively small variation of crustal thickness can induce Rayleigh to Love wave conversions between 0.02 and 0.1 Hz frequency. The calculated amplitudes of the Love waves are significant (up to 35% of the amplitude of the incoming Rayleigh waves), but they are too small to fit the observed amplitude anomaly. The observed converted waves and the numerical results nevertheless indicate that surface wave conversions can be significant across strong lateral crustal heterogeneities. In particular, the conversions due to changes in crustal thickness are located in the period interval which is routinely used for estimation of Ms.