FOIA: Uppermost Mantle Structure in Southern Eurasia

UPPERMOST_MANTLE_STRUCTURE.pdf
Uppermost Mantle Structure in Southern Eurasia
Uppermost Mantle Structure in Southern Eurasia From Pn Tomography and Sn Attenuation
Document date: 1996-06-01
Department: Dept. of Physics, New Mexico State Univ.
Author: Thomas M. Hearne, James F. Ni
Document type: report
pages: 60


Archivist's Notes: Fair quality document on 10 hole punched forms. Form 298 cover page. Many graphs. Unlimited distribution.

This report was sponsored by the Air Force Office of Scientific Research.
It was written by Hearn, Thomas and Ni of the Department of Physics at University of New Mexico in 1996.
Title: Uppermost Mantle Structure in Southern Eurasia from PN Tomography and SN Attenuation – 60 pages.

This research was conducted to find the most appropriate monitoring system for nuclear events by assessing the earth’s structure in Southern Eurasia. It was viewed with reference to Pn travel time tomography and regional mapping of Lg and Sn waves.

The conclusion is on Pdf pge 35
In the Middle East, the Turkish-Iranian Plateau has a similar seismic structure to that of the western United States and so nuclear discrimination methods developed for the western U.S. would be suitable for the Turkish-Iranian Plateau.
Sn can be used for nuclear monitoring only in Arabian Shield, Russian Platform and southern Tibet.

Lg can be used for nuclear monitoring in areas where the Sn wave cannot, if stations are situated within geologic provinces. Lg barriers are the Black Sea and the Caspian Sea, the Caucasus Mountains, Zagros Mountains, the Indus-Tangpo suture, and the Himalayas

This document is related to the Vela incident:
FOIA: Characteristics of seismic sources and structures in Iran and the Caucasus

Storming Media charges $8.95 for the same document - ATS made it availabe for free

Abstract: This project has investigated the seismic characteristics of southern Eurasia through Pn travel time tomography and the regional mapping of attenuation for high frequency Sn and Lg waves. Pn tomography results indicate that much of the uppermost mantle beneath southern Eurasia has low P-wave velocity and a small amount of melt. Mapping of Sn propagation efficiency confirms that regions with low Pn velocity generally do not propagate Sn waves efficiently. This is especially true for the Turkish-Iranian Plateau and the northern Tibetan Plateau. In contrast to Sn waves, Lg waves propagate within the crust and are insensitive to mantle properties, but are affected by changes in crustal structure. Lg is weakened or completely absent when propagation paths obliquely cross major tectonic boundaries such as the Himalaya Mountains, the Tarim Basin, the Caucasus Mountains, or the oceanic crust of the Black and Caspian Seas. The high attenuation of Sn in many parts of southern Eurasia limits its use in regional nuclear monitoring; however, Lg can be observed provided data is available from stations sited within each geologic province.

In addition to the information that frozen snowman has given, the introduction stated the objectives of the report.

Regional studies serve a twofold purpose: (1) regional data can provide stable yield estimates for underground nuclear explosions, and (2) regional data can discriminate between explosions and earthquakes. For both these goals, understanding the timing and strength of regional seismic phases is critical.

Obviously this report is related to enforcing the nuclear test ban treaty by being able to detect any nuclear explosions in this region.

I have to commend frozen snowman for the previous explanation on this document because it leaves without much more to add.