Conversion of Source Parameters

• The MCMTpy provides a series of scripts for source parameter calculation and conversion. The MomentTensor script refers to some theories and codes of Obspy MoPaD and Introduction to Seismology (Yongge Wan), mainly including:

• We do not recommend using relative paths because of the possibility of errors. Absolute paths are preferred.

The installation

• jupyter notebook:

  # import MomentTensor
  from MCMTpy import MomentTensor as MTpy
  
  # get __doc__
  MTpy.__doc__.strip().split("\n")
  

str_dip_rake to mt

• jupyter notebook:

  # function: str_dip_rake2MT
  MTpy.str_dip_rake2MT.__doc__.strip().split("\n")
  
  # input
  strike = 50
  dip = 50
  rake = 100
  
  A = MTpy.str_dip_rake2MT(strike,dip,rake)
  A.mt
  

The conversion between str_dip_rake and A/N vector

• jupyter notebook:

  #-----------------------------------------------#
  # function: str_dip_rake2AN
  MTpy.str_dip_rake2AN.__doc__.strip().split("\n")
  
  # str_dip_rake to A/N vector
  # input
  strike = 50
  dip = 50
  rake = 100
  
  A,N = MTpy.str_dip_rake2AN(strike,dip,rake)
  print('A = ', A)
  print('N = ', N)
  
  #-----------------------------------------------#
  # function AN2str_dip_rake
  MTpy.AN2str_dip_rake.__doc__.strip().split("\n")
  
  # A/N vector to str_dip_rake
  # input
  A = np.array([0.37330426, -0.53992106, -0.75440651])
  N = np.array([-0.58682409,  0.49240388, -0.64278761])
  
  DD = MTpy.AN2str_dip_rake(A,N)
  print('strike = ', DD.strike)
  print('dip = ', DD.dip)
  print('rake = ', DD.rake)
  

The conversion between A/N vector and P/T/N vector

• jupyter notebook:

  #-----------------------------------------------#
  # function AN2TPN
  MTpy.AN2TPN.__doc__.strip().split("\n")
  
  # Calculate the T-axis, P-axis and N-axis according to the slip vector (A) and fault plane direction vector (N)
  # input
  A = np.array([0.37330426, -0.53992106, -0.75440651])
  N = np.array([-0.58682409,  0.49240388, -0.64278761])
  
  T,P,Null = MTpy.AN2TPN(A,N)
  print('T = ', T)
  print('P = ', P)
  print('Null = ', Null)
  
  #-----------------------------------------------#
  # function TP2AN
  MTpy.TP2AN.__doc__.strip().split("\n")
  
  # Calculate the slip vector (A) and fault plane direction vector (N) according to the T-axis and P-axis
  # input
  T = np.array([-0.15098132, -0.03359972, -0.98796544])
  P = np.array([0.67891327, -0.72996397, -0.07892648])
  
  A,N = MTpy.TP2AN(T,P)
  print('A = ', A)
  print('N = ', N)
  

mt to P/T/N vector

• jupyter notebook:

  # function MT2TPN
  MTpy.MT2TPN.__doc__.strip().split("\n")
  
  # input
  strike = 50
  dip = 50
  rake = 100
  
  A = MTpy.str_dip_rake2MT(strike,dip,rake)
  T, P, Null = MTpy.MT2TPN(A)
  print('T = ', T)
  print('P = ', P)
  print('Null = ', Null)
  

P/T/N vector to P/T/N vector’s stirke and dip

• jupyter notebook:

  # function vector2str_dip
  MTpy.vector2str_dip.__doc__.strip().split("\n")
  
  # input
  A = np.array([0.37330426, -0.53992106, -0.75440651])
  
  CC = MTpy.vector2str_dip(A)
  print('A.strike = ', CC.strike)
  print('A.dip = ', CC.dip)
  

Describe_fault_plane with two str_dip_rake

• jupyter notebook:

  # function describe_fault_plane
  MTpy.describe_fault_plane.__doc__.strip().split("\n")
  
  # input
  strike = 50
  dip = 50
  rake = 100
  
  A = MTpy.str_dip_rake2MT(strike,dip,rake)
  CC = MTpy.describe_fault_plane(A.mt)
  print('FM_1 = ', CC[0,:])
  print('FM_2 = ', CC[1,:])