Accession Number:

ADA023949

Title:

Additional Investigation of Earthquakes with Low M sub s to m sub b Ratios in the Tibet-Himalaya Region

Descriptive Note:

Technical rept.

Corporate Author:

TELEDYNE GEOTECH ALEXANDRIA VA SEISMIC DATA ANALYSIS CENTER

Report Date:

1975-07-10

Pagination or Media Count:

69.0

Abstract:

Further analysis of the anomalous events in the eastern Himalaya region with an expanded set of stations shows that the M sub s values of these events are indeed low compared to m sub b. Other characteristics of these events indicate, however, that all these events are earthquakes rather than explosions. Dilatational first motion for P waves, long period S to Rayleigh, short period S to P wave amplitude ratios are characteristic of earthquakes. Readings of the pP phase where available as well as epicenter calculations indicate that the anomalous event hypocenter are shallow, i.e., less than 80 km. Data quality did not permit the refinement of epicenter locations. A search for additional anomalous events with respect to M sub s - m sub b in a wider area in the Himalayan-Tibet region indicated that there are no other contiguous areas containing anomalous events in this region beyond those already found.

Subject Categories:

  • Seismology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE