esys.downunder.seismic Package¶
Classes¶
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class esys.downunder.seismic.HTIWave(domain, v_p, v_s, wavelet, source_tag, source_vector=[1.0, 0.0, 0.0], eps=0.0, gamma=0.0, delta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=None, absorption_cut=0.01, lumping=True, disable_fast_assemblers=False)¶
- Bases: - esys.downunder.seismic.WaveBase- Solving the HTI wave equation (along the x_0 axis) - Note: - In case of a two dimensional domain a horizontal domain is considered, i.e. the depth component is dropped. - 
__init__(domain, v_p, v_s, wavelet, source_tag, source_vector=[1.0, 0.0, 0.0], eps=0.0, gamma=0.0, delta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=None, absorption_cut=0.01, lumping=True, disable_fast_assemblers=False)¶
- initialize the VTI wave solver - Parameters: - domain (Domain) – domain of the problem
- v_p (escript.Scalar) – vertical p-velocity field
- v_s (escript.Scalar) – vertical s-velocity field
- wavelet (Wavelet) – wavelet to describe the time evolution of source term
- source_tag ('str' or 'int') – tag of the source location
- source_vector – source orientation vector
- eps – first Thompsen parameter
- delta – second Thompsen parameter
- gamma – third Thompsen parameter
- rho – density
- dt – time step size. If not present a suitable time step size is calculated.
- u0 – initial solution. If not present zero is used.
- v0 – initial solution change rate. If not present zero is used.
- absorption_zone – thickness of absorption zone
- absorption_cut – boundary value of absorption decay factor
- lumping – if True mass matrix lumping is being used. This is accelerates the computing but introduces some diffusion.
- disable_fast_assemblers – if True, forces use of slower and more general PDE assemblers
 
- domain (
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getTimeStepSize()¶
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setQ(q)¶
- sets the PDE q value - Parameters: - q – the value to set 
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update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
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class esys.downunder.seismic.Ricker(f_dom=40, t_dom=None)¶
- Bases: - esys.downunder.seismic.Wavelet- The Ricker Wavelet w=f(t) - 
__init__(f_dom=40, t_dom=None)¶
- Sets up a Ricker wavelet wih dominant frequence - f_domand center at time- t_dom. If- t_domis not given an estimate for suitable- t_domis calculated so f(0)~0.- Note: - maximum frequence is about 2 x the dominant frequence. 
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getAcceleration(t)¶
- get the acceleration f’‘(t) at time - t
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getCenter()¶
- Return value of wavelet center 
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getTimeScale()¶
- Returns the time scale which is the inverse of the largest frequence with a significant spectral component. 
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getValue(t)¶
- get value of wavelet at time - t
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getVelocity(t)¶
- get the velocity f’(t) at time - t
 
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class esys.downunder.seismic.SimpleSEGYWriter(receiver_group=None, source=0.0, sampling_interval=0.004, text='some seimic data')¶
- Bases: - object- A simple writer for 2D and 3D seismic lines, in particular for synthetic data - Typical usage: - from esys.escript import unitsSI as U sw=SimpleSEGYWriter([0.,100*U.m,200*U,m,300.], source=200*U.m, sampling_interval=4*U.msec) while n < 10: sw.addRecord([i*2., i*0.67, i**2, -i*7]) sw.write('example.segy') - Note: - the writer uses - obspy- 
__init__(receiver_group=None, source=0.0, sampling_interval=0.004, text='some seimic data')¶
- initalize writer - Parameters: - receiver_group – list of receiver coordinates (in meters). For the 2D case a list of floats is given, for the 3D case a list of coordinate tuples are given
- source – coordinates of the source (in meters). For the 2D case a single floats is given, for the 3D case a coordinate tuples
- sampling_interval – sample rate in seconds
- text – a text for the header file (e.g a description)
 
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COORDINATE_SCALE= 1000.0¶
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addRecord(record)¶
- Adds a record to the traces. A time difference of sample_interval between two records is assumed. The record mast be a list of as many values as given receivers or a float if a single receiver is used. - Parameters: - record – list of tracks to be added to the record. 
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getSamplingInterval()¶
- returns the sampling interval in seconds. 
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obspy_available()¶
- for checking if the obspy module is available 
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write(filename)¶
- writes to segy file - Parameters: - filename – file name - Note: - the function uses the - obspymodule.
 
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class esys.downunder.seismic.SonicHTIWave(domain, v_p, wavelet, source_tag, source_vector=[1.0, 0.0], eps=0.0, delta=0.0, azimuth=0.0, dt=None, p0=None, v0=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- Bases: - esys.downunder.seismic.WaveBase- Solving the HTI wave equation (along the x_0 axis) with azimuth (rotation around verticle axis) under the assumption of zero shear wave velocities The unknowns are the transversal (along x_0) and vertial stress (Q, P) - Note: - In case of a two dimensional domain the second spatial dimenion is depth. - 
__init__(domain, v_p, wavelet, source_tag, source_vector=[1.0, 0.0], eps=0.0, delta=0.0, azimuth=0.0, dt=None, p0=None, v0=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- initialize the HTI wave solver - Parameters: - domain (Doamin) – domain of the problem
- v_p (escript.Scalar) – vertical p-velocity field
- v_s (escript.Scalar) – vertical s-velocity field
- wavelet (Wavelet) – wavelet to describe the time evolution of source term
- source_tag ('str' or 'int') – tag of the source location
- source_vector – source orientation vector
- eps – first Thompsen parameter
- azimuth – azimuth (rotation around verticle axis)
- gamma – third Thompsen parameter
- rho – density
- dt – time step size. If not present a suitable time step size is calculated.
- p0 – initial solution (Q(t=0), P(t=0)). If not present zero is used.
- v0 – initial solution change rate. If not present zero is used.
- absorption_zone – thickness of absorption zone
- absorption_cut – boundary value of absorption decay factor
- lumping – if True mass matrix lumping is being used. This is accelerates the computing but introduces some diffusion.
 
- domain (
 - 
getTimeStepSize()¶
 - 
update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
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class esys.downunder.seismic.SonicWave(domain, v_p, wavelet, source_tag, dt=None, p0=None, p0_t=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- Bases: - esys.downunder.seismic.WaveBase- Solving the sonic wave equation - p_tt = (v_p**2 * p_i)_i + f(t) * delta_swhere (p-) velocity v_p.- f(t) is wavelet acting at a point source term at positon s - 
__init__(domain, v_p, wavelet, source_tag, dt=None, p0=None, p0_t=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- initialize the sonic wave solver - Parameters: - domain (Domain) – domain of the problem
- v_p (escript.Scalar) – p-velocity field
- wavelet (Wavelet) – wavelet to describe the time evolution of source term
- source_tag ('str' or 'int') – tag of the source location
- dt – time step size. If not present a suitable time step size is calculated.
- p0 – initial solution. If not present zero is used.
- p0_t – initial solution change rate. If not present zero is used.
- absorption_zone – thickness of absorption zone
- absorption_cut – boundary value of absorption decay factor
- lumping – if True mass matrix lumping is being used. This is accelerates the computing but introduces some diffusion.
 
- domain (
 - 
getTimeStepSize()¶
 - 
update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
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class esys.downunder.seismic.TTIWave(domain, v_p, v_s, wavelet, source_tag, source_vector=[0.0, 1.0], eps=0.0, delta=0.0, theta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- Bases: - esys.downunder.seismic.WaveBase- Solving the 2D TTI wave equation with - sigma_xx= c11*e_xx + c13*e_zz + c15*e_xz- sigma_zz= c13*e_xx + c33*e_zz + c35*e_xz- sigma_xz= c15*e_xx + c35*e_zz + c55*e_xz- the coefficients - c11,- c13, etc are calculated from the tompsen parameters- eps,- deltaand the tilt- theta- Note: - currently only the 2D case is supported. - 
__init__(domain, v_p, v_s, wavelet, source_tag, source_vector=[0.0, 1.0], eps=0.0, delta=0.0, theta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=300.0, absorption_cut=0.01, lumping=True)¶
- initialize the TTI wave solver - Parameters: - domain (Domain) – domain of the problem
- v_p (escript.Scalar) – vertical p-velocity field
- v_s (escript.Scalar) – vertical s-velocity field
- wavelet (Wavelet) – wavelet to describe the time evolution of source term
- source_tag ('str' or 'int') – tag of the source location
- source_vector – source orientation vector
- eps – first Thompsen parameter
- delta – second Thompsen parameter
- theta – tilting (in Rad)
- rho – density
- dt – time step size. If not present a suitable time step size is calculated.
- u0 – initial solution. If not present zero is used.
- v0 – initial solution change rate. If not present zero is used.
- absorption_zone – thickness of absorption zone
- absorption_cut – boundary value of absorption decay factor
- lumping – if True mass matrix lumping is being used. This is accelerates the computing but introduces some diffusion.
 
- domain (
 - 
getTimeStepSize()¶
 - 
update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
- 
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class esys.downunder.seismic.VTIWave(domain, v_p, v_s, wavelet, source_tag, source_vector=[0.0, 0.0, 1.0], eps=0.0, gamma=0.0, delta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=None, absorption_cut=0.01, lumping=True, disable_fast_assemblers=False)¶
- Bases: - esys.downunder.seismic.WaveBase- Solving the VTI wave equation - Note: - In case of a two dimensional domain the second spatial dimenion is depth. - 
__init__(domain, v_p, v_s, wavelet, source_tag, source_vector=[0.0, 0.0, 1.0], eps=0.0, gamma=0.0, delta=0.0, rho=1.0, dt=None, u0=None, v0=None, absorption_zone=None, absorption_cut=0.01, lumping=True, disable_fast_assemblers=False)¶
- initialize the VTI wave solver - Parameters: - domain (Domain) – domain of the problem
- v_p (escript.Scalar) – vertical p-velocity field
- v_s (escript.Scalar) – vertical s-velocity field
- wavelet (Wavelet) – wavelet to describe the time evolution of source term
- source_tag ('str' or 'int') – tag of the source location
- source_vector – source orientation vector
- eps – first Thompsen parameter
- delta – second Thompsen parameter
- gamma – third Thompsen parameter
- rho – density
- dt – time step size. If not present a suitable time step size is calculated.
- u0 – initial solution. If not present zero is used.
- v0 – initial solution change rate. If not present zero is used.
- absorption_zone – thickness of absorption zone
- absorption_cut – boundary value of absorption decay factor
- lumping – if True mass matrix lumping is being used. This is accelerates the computing but introduces some diffusion.
- disable_fast_assemblers (boolean) – if True, forces use of slower and more general PDE assemblers
 
- domain (
 - 
getTimeStepSize()¶
 - 
setQ(q)¶
- sets the PDE q value - Parameters: - q – the value to set 
 - 
update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
- 
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class esys.downunder.seismic.WaveBase(dt, u0, v0, t0=0.0)¶
- Bases: - object- Base for wave propagation using the Verlet scheme. - u_tt = A(t,u), u(t=t0)=u0, u_t(t=t0)=v0- with a given acceleration force as function of time. - a_n=A(t_{n-1}) v_n=v_{n-1} + dt * a_n u_n=u_{n-1} + dt * v_n - 
__init__(dt, u0, v0, t0=0.0)¶
- set up the wave base - Parameters: - dt – time step size (need to be sufficiently small)
- u0 – initial value
- v0 – initial velocity
- t0 – initial time
 
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getTimeStepSize()¶
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update(t)¶
- returns the solution for the next time marker t which needs to greater than the time marker from the previous call. 
 
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Functions¶
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esys.downunder.seismic.createAbsorptionLayerFunction(x, absorption_zone=300.0, absorption_cut=0.01, top_absorption=False)¶
- Creates a distribution which is one in the interior of the domain of - xand is falling down to the value ‘absorption_cut’ over a margin of thickness ‘absorption_zone’ toward each boundary except the top of the domain.- Parameters: - x (escript.Data) – location of points in the domain
- absorption_zone – thickness of the absorption zone
- absorption_cut – value of decay function on domain boundary
 - Returns: - function on ‘x’ which is one in the iterior and decays to almost zero over a margin toward the boundary. 
- x (
Others¶
- OBSPY_AVAILABLE