#28 Why is PGV jumping largely along the surface?

[hanjianbin]

Dear ,I study the influence of difference of the media in the basin! The wave velocity rate in and out of the basin is 1:1.25,1:2 ,1:3 .Then I chose the PGV as the parameter. But I found them jumping largely ! Is it right? The graphic and the par are fallowing.

[Jean-Paul Ampuero]

Dear user,
If you send me the matlab script you wrote to plot the figure PGV*.png I can try to reproduce your problem.

[hanjianbin]

I use the Origin to plot the figure .and use matlab to extraction data.

[Jean-Paul Ampuero]

Please send me the matlab script you used to extract the data.

(As a general guideline, when requesting software support, please always provide all the information needed to reproduce your problem.)

[hanjianbin]

they are like following! thank you for your help!

[Jean-Paul Ampuero]

Apparently you are extracting PGV from velocity snapshot outputs. This can cause an aliasing problem due to the coarse temporal sampling of the snapshots, i.e. the time between snapshots may be too long to accurately catch the velocity maxima. I recommend you to set more receivers and a high sampling rate in the &REC_LINE input block, and then extract the PGV from the seismograms.

[hanjianbin]

OK ,thank you very much ! I will try my best as you say.

[Jean-Paul Ampuero]

I attach an example Par.inp file and a figure made with the following matlab commands:

d=sem2d_read_seis();
uxm = max(d.ux);
plot(d.x/1e3,uxm)
xlabel('Horizontal distance (m)'); ylabel ('PGV (m/s)'); grid