Hi, Brad,<div><br></div><div>Thank you very much for your suggestions ! </div><div><br></div><div>I searched some papers about faulting, yes, you are right, most people use stress state to evaluate the stability of an fault, rather than force. </div>
<div><br></div><div>I find you replied most of questions in mailing list. A lot of people, I think, would like to shear your work, however, you have a better understanding of Pylith or the knowledge about earthquake.</div>
<div><br></div><div>Thanks again!</div><div><br></div><div>Best Regards!</div><div>Qian Gao</div><div><br></div><div><br><br><div class="gmail_quote">On Mon, Oct 24, 2011 at 12:02 PM, Brad Aagaard <span dir="ltr"><<a href="mailto:baagaard@usgs.gov">baagaard@usgs.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Qian,<br>
<br>
In PyLith the shear and normal tractions on a fault are available via the output. Most other finite-element codes that model faults also include this feature. These tractions are calculated using the fault implementation, not from calculating the stresses within the volume elements. Alternatively, you can calculate the stress tensor on the face of a volume element and use the face normal to get a traction. However, in lower order finite-elements the stresses are not continuous across element boundaries (the displacement field is continuous but the strains and stresses are not).<br>
<br>
In most studies that I am aware of the Mohr-Coulomb criterion is applied locally using the shear and normal tractions. This accounts for potential spatial variation of the tractions due to loading, heterogeneous material properties, etc that cause failure on a subset of the fault.<br>
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Regards,<br><font color="#888888">
Brad</font><div><div></div><div class="h5"><br></div></div></blockquote></div></div>