class FocalMechanism(force_resource_id=True, *args, **kwargs)[source]

Bases: obspy.core.event.base.__FocalMechanism

This class describes the focal mechanism of an event. It includes different descriptions like nodal planes, principal axes, and a moment tensor. The moment tensor description is provided by objects of the class MomentTensor which can be specified as child elements of FocalMechanism.

  • resource_id (ResourceIdentifier) Resource identifier of FocalMechanism.
  • force_resource_id (bool, optional) If set to False, the automatic initialization of resource_id attribute in case it is not specified will be skipped.
  • triggering_origin_id (ResourceIdentifier, optional) Refers to the resource_id of the triggering origin.
  • nodal_planes (NodalPlanes, optional) Nodal planes of the focal mechanism.
  • principal_axes (PrincipalAxes, optional) Principal axes of the focal mechanism.
  • azimuthal_gap (float, optional) Largest azimuthal gap in distribution of stations used for determination of focal mechanism. Unit: deg
  • station_polarity_count (int, optional)
  • misfit (float, optional) Fraction of misfit polarities in a first-motion focal mechanism determination. Decimal fraction between 0 and 1.
  • station_distribution_ratio (float, optional) Station distribution ratio (STDR) parameter. Indicates how the stations are distributed about the focal sphere (Reasenberg and Oppenheimer 1985). Decimal fraction between 0 and 1.
  • method_id (ResourceIdentifier, optional) Resource identifier of the method used for determination of the focal mechanism.
  • waveform_id (list of WaveformStreamID, optional) Refers to a set of waveform streams from which the focal mechanism was derived.
  • evaluation_mode (str, optional) Evaluation mode of FocalMechanism. See EvaluationMode for allowed values.
  • evaluation_status (str, optional) Evaluation status of FocalMechanism. See EvaluationStatus for allowed values.
  • moment_tensor (MomentTensor, optional) Moment tensor description for this focal mechanism.
  • comments (list of Comment, optional) Additional comments.
  • creation_info (CreationInfo, optional) Creation information used to describe author, version, and creation time.


For handling additional information not covered by the QuakeML standard and how to output it to QuakeML see the ObsPy Tutorial.


__abstractmethods__ frozenset() -> empty frozenset object
__doc__ str(object=’‘) -> str
__module__ str(object=’‘) -> str
__slots__ tuple() -> empty tuple
__weakref__ list of weak references to the object (if defined)
defaults dict() -> new empty dictionary
do_not_warn_on list() -> new empty list
item tuple() -> empty tuple
key str(object=’‘) -> str
readonly list() -> new empty list
warn_on_non_default_key bool(x) -> bool

Public Methods

pop If key is not found, d is returned if given, otherwise KeyError is raised.
popitem as a 2-tuple; but raise KeyError if D is empty.

Private Methods


Private methods are mainly for internal/developer use and their API might change without notice.

_pretty_str Return better readable string representation of AttribDict object.

Special Methods

__dir__ default dir() implementation
__eq__ Two instances are considered equal if all attributes and all lists
__format__ default object formatter
__getattr__ Py3k hasattr() expects an AttributeError no KeyError to be
__new__ Create and return a new object.
__reduce__ helper for pickle
__reduce_ex__ helper for pickle
__setattr__ Custom property implementation that works if the class is
__sizeof__ size of object in memory, in bytes
__str__ Fairly extensive in an attempt to cover several use cases.