Authors / CoAuthors
Wilkie, J. | Gibson, G. | Wesson, V.
Abstract
A new expression with superior consistency in the calculation of magnitude from earthquake coda duration has been developed. The need to take into consideration the site, the seismograph characteristics and the source has been investigated. The expression is valid for distances up to 1000 km in southeast Australia except where the source is located on some other major geological foundation, for example the Australian shield or the Tasman Sea. The expression takes the form: MD = p1 + p2(log(SDD))P3 + p4Re-p5R . MD is duration magnitude, and the parameters in the above expression are determined by regression based on local magnitude ML. Duration, D, is in seconds, R is the hypocentral distance in kilometres, and pn are parameters. Parameter p1 zeroes the function to give values similar to ML and accounts for the definition of duration; p2 and p3 give the shape of the variation with duration; and p4 and p5 give the variation with distance. SD is the duration site correction factor , which varies from site to site and can be easily determined by comparing particular site durations with average durations. If the network data are electronically recorded, the value of SD for all sites can be continually monitored and updated. Because of the different methods of estimating D for the analogue and digital seismographs, a value of the parameter p1 for each seismograph type is necessary. analogue MD = - 0.46 + 0.45(log(SDD))2.4 + 0.0045Re-0.002R . digital MD = - 0.20 + 0.45(log(SDD))2.4 + 0.0045Re-0.002R . The above expressions present the relationship between MD, D (measured to double the background level) and R in southeast Australia for magnitudes between MD 0 and 5 and for distances from a few km to 1000 km.
Product Type
document
eCat Id
81411
Contact for the resource
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Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GA PublicationJournal
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- VIC
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1995-01-01T00:00:00
Creation Date
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unknown
Topic Category
geoscientificInformation
Series Information
AGSO Journal of Australian Geology and Geophysics 15:4:469-474
Lineage
Unknown
Parent Information
Extents
[-40.0, -34.0, 140.5, 150.0]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Source data not available.