On the CTBT Monitoring Potential of Using LG-Phase Arrival Times at Local and Regional Distance Ranges

• Main Authors: Pinsky, Vladimir I., Husebye, Eystein S., Matveeva, Tatiana S., Fedorenko, Yury V.
• Other Authors: GEOPHYSICAL INST OF ISRAEL HOLON (ISRAEL)
• Format: Text
• Language: English
• Published: 2008
• Subjects: Test Facilities; Equipment and Methods; Target Direction; Range and Position Finding; *MONITORING; *ARRIVAL; *RANGE(DISTANCE); *PHASE; SYMPOSIA; SURFACE WAVES; PROBABILITY; TIME; GROUP VELOCITY; BEAM FORMING; GROUND BASED; EQUATIONS; EPICENTERS; HILBERT SPACE; PROPAGATION; NUCLEAR EXPLOSIONS; BALTIC SEA; ALGORITHMS; ISRAEL; *ARRIVAL TIME; FOREIGN REPORTS; Apatity; Bergen; Norway; Fennoscandia
• Online Access: http://www.dtic.mil/docs/citations/ADA516244; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA516244

The prominent Lg wave is nearly always observed at local and regional distances. It is a surface wave propagating with almost constant group velocity around 3.5 km/s over a vast distance range of hundreds to thousands of kilometers. Thus, Lg propagation should in principle simplify epicenter location schemes, based on relative travel time equations. In our ongoing efforts to accomplish this we computed Hilbert or STA-envelopes and showed that in many recordings from Fennoscandia and Central Europe the Lg group velocities measured using the envelope peak arrival times are remarkably consistent. However, they tightly concentrate around 3.4 km/sec for the Baltic shield of Fennoscandia and around 3.2 km/sec for the much younger crust of Central Europe. These Lg picks were subsequently used in the Pinsky (2008) relative time location algorithms of "group beamforming" and "probabilistic beamforming" for refined epicenter locations in Balticum. Presented at the Conference on Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies (30th), held in Portsmouth, VA, on 23-25 Sep 2008. Published in the proceedings of the conference, p435-444, 2008. Prepared in collaboration with Bergen Center of Computational Science, UNIFOB/UoBergen, Norway, and the Polar Geophysical Institute, Apatity, Russia. Sponsored in part by the National Nuclear Security Administration (NNSA) and the Bergen Center of Computational Science. The original document contains color images.