init

BIN/fpsol.py

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+#function to determine the strike, rake and dip from a dc moment tensor
+#(full and deviatoric moment tenors need to be decomposed first
+
+import math
+import numpy as np
+
+def fpsol(nu,u):
+
+    """
+    reads the vector normal and slip vector returning strike, rake, dip
+    """
+
+
+    dip=np.arccos(-1*nu[2])
+    if nu[0] ==0. and nu[1] == 0.:
+        str=0.
+    else:
+        str=np.arctan2(-1*nu[0],nu[1])
+
+
+
+    sstr=np.sin(str)
+    cstr=np.cos(str)
+    sdip=np.sin(dip)
+    cdip=np.cos(dip)
+
+
+    if abs(sdip) > 0.:
+        rake=np.arcsin(-1*u[2]/np.sin(dip));
+    else:
+        arg1=1.
+        arg2=u[2]
+        arg=np.sign(arg2)
+        if arg < 0.:
+            rake=np.pi
+        else:
+            rake=0.
+
+    slambda=np.sin(rake)
+    cdsl=cdip*slambda
+
+    if abs(sstr) > abs(cstr):
+        clambda=(u[1]+cdsl*cstr)/sstr
+    else:
+        clambda=(u[0]-cdsl*sstr)/cstr
+
+    if slambda == 0. and clambda == 0.:
+        slip=0.
+    else:
+        slip=np.arctan2(slambda,clambda)
+
+
+    if dip > np.pi/2:
+        dip=np.pi-dip
+        str=str+np.pi
+        slip=2*np.pi-slip
+
+    if str < 0.: 
+        str=str+2*np.pi
+
+    if slip >= np.pi: 
+        slip=slip-2*np.pi;
+
+
+    str=str*180/np.pi
+    rake=slip*180/np.pi
+    dip=dip*180/np.pi
+
+    return str, rake, dip