Is it only the distance which matters or are there certain specific criteria qualifying them?
In General, It was said that, approximately records with less than 15 km have near-field effects and, more than 20 km have far-field effects.
However, if you want to be more accurate, you should consider earthquake record contents. You should look at velocity time history of the record to see whether it has great pulse or not, it can be seen from FFT and power spectra too.
I think,
Consideration the activity of faults, characteristics of hsitorical earthquake events on the location, i.e, Depth, magnitude, Impact Radius, ...can effect to classification of faults. Because, Some of far fults with high activitiy may effect on the your location more than near fults.
Thank you all for your apt reply! But I would like to go much deeper into these concepts . As in how are the specific characteristics of Near and far field earthquakes. Could you suggest me some basic/interesting papers which categorize these in detail. Would like to get more info about their earthquake contents
"identification of near-fault earthquake record characteristics"
I am not an expert in this field, but it might be helpful to consider "directivity":
Somerville, P. G., Smith, N. F., Graves, R. W., and Abrahamson, N. A. (1997). “Modification of empirical strong ground motion attenuation relations to include the amplitude and duration effects of rupture directivity.” Seismological Research Letters, 68(1), 199–222.
Near-field earthquakes have some characteristics that differ them from far-field ones. These earthquakes have higher accelerations and restricted frequency content in higher frequencies than far-field ones. Also their records have pulses in beginning of record with high period and high domain. These pulses are much considerable when the Forward directivity takes place, therefore the records change from Board-Band condition to Pulse-Like ones.These pulse-type ground motions often contain one or more distinct pulses in the acceleration-time, velocity-time, and displacement-time histories, and more frequently in the velocity. These pluses result in the occurrence of the amount of maximum of Fourier spectrum in limited periods unlike the amount of maximum of Fourier spectrum in far-field earthquakes that occur in wide-ranging of periods.
where can i get the near and far field earthquake data in .dat or excel or .txt format, can you please suggest the sites please.
Well it depends in reality on the distance from the epicenter
in experimentation, the larger intensity shorter period is the near-fault and the larger period is the far-field
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