Teleseismic magnitude relations

Markus Båth Markus Båth

doi:10.4401/ag-4664

Abstract

Using available sets of magnitude determinations, primarily from Uppsala seismological bulletin, various extensions are made of the Zurich magnitude recommendations of 1967. Thus, body-wave magnitude (m) and surface-wave magnitudes (M) are related to each other for 12 different earthquake regions as well as world-wide. Depth corrections for M are derived for all focal depths. Formulas are developed which permit calculation of M also from vertical component long-period seismographs. Body-wave magnitudes from broad-band and narrow-band short-period seismographs are compared and relations deduced. Applications are made both to underground nuclear explosions and to earthquakes. The possibilities of explosion-earthquake discrimination on the basis of magnitudes are examined, as well as the determination of explosive yield from magnitudes. For earthquakes, relations between magnitudes of main earthquakes and largest aftershocks are investigated. A world-wide station network for more homogeneous magnitude determinations is suggested in order to provide the necessary reference system.

Highlights

Depth corrections for M are derived for all focal depths
At the assembly of the International Association of Seismology and Physics of the Earth's Interior (IASPEI) in Zurich in 1967, certain recommendations were adopted in order to create better homogeneity in seismic magnitude calculations
Numerous sets of magnitude determinations have been collected which call for more detailed study, both in order to revise earlier magnitude relations and to make any possible extensions

Summary

Introduction

At the assembly of the International Association of Seismology and Physics of the Earth's Interior (IASPEI) in Zurich in 1967, certain recommendations were adopted in order to create better homogeneity in seismic magnitude calculations. There are numerous applications of the magnitude concept which can be subjected to further investigation and possible refinement, such as for discrimination between explosions and earthquakes, for determination of explosive yield, and in the study of aftershock sequences. Problems as those just mentioned and related ones, together with the present existence of homogeneous sets of magnitude determinations, prompted the present study. Numerous valuable papers have appeared in the literature with close relations to one section or another in the following These papers would rather deserve a special detailed review than brief mentioning here. A.: 41 ̊00.4 ́ N, 73 ̊54.5 ́ W; Umeå (WWSSN), Sweden: 63 ̊48.9 ́ N, 20 ̊ 14.2 ́ E; Uppsala, Sweden: 59 ̊51.5 ́ N, 17 ̊37.6 ́ E

Methods

Findings

11. Conclusions