Simple function to attach available moment-tensor information to a given catalogue by downloading and integrating John Ristau's mt solutions.

attach_geonet_mt.py

def get_geonet_moment_tensor(catalog):
    """
    Get the moment tensor info for a given set of events, and add them to the
    events.

    Use John Ristau's MT catalog here:
        `https://raw.githubusercontent.com/GeoNet/data/master/moment-tensor/GeoNet_CMT_solutions.csv`
    which does not include all events, if events are not in the database they
    will warn that they are not found.

    :param catalog: obspy.core.event.Event to get moment tensor for.

    .. Note::
        Works in-place on given event.
    """
    import urllib.request
    import csv

    from obspy.core.event import (
        FocalMechanism, MomentTensor, Origin, CreationInfo, ResourceIdentifier,
        NodalPlane, NodalPlanes, PrincipalAxes, Axis, Magnitude, Tensor)
    from obspy import UTCDateTime

    # Build local database
    response = urllib.request.urlopen(
        "https://raw.githubusercontent.com/GeoNet/data/master/moment-tensor/"
        "GeoNet_CMT_solutions.csv")
    reader = csv.DictReader(response.read().decode('utf-8').splitlines())

    moment_tensors = [line for line in reader]
    for event in catalog:
        mt = [_mt for _mt in moment_tensors
              if _mt['PublicID'] == event.resource_id.id.split('/')[-1]]
        if len(mt) == 0:
            print("Event %s not found in database, skipping" %
                  event.resource_id.id.split('/')[-1])
            continue
        mt = mt[0]
        fm_origin = Origin(
            latitude=float(mt['Latitude']), longitude=float(mt['Longitude']),
            depth=float(mt['CD']) * 1000,
            time=UTCDateTime.strptime(mt['Date'], "%Y%m%d%H%M%S"),
            origin_type="centroid", evaluation_mode="automatic",
            creation_info=CreationInfo(agency_id="GNS", author="John Ristau"),
            method_id=ResourceIdentifier("GNS_MT_solution"))
        local_mag = Magnitude(mag=float(mt['ML']), magnitude_type="ML",
                              origin_id=fm_origin.resource_id)
        moment_mag = Magnitude(mag=float(mt['Mw']), magnitude_type="MW",
                               origin_id=fm_origin.resource_id)
        event.origins.append(fm_origin)
        event.magnitudes.append(local_mag)
        event.magnitudes.append(moment_mag)

        fm = FocalMechanism(
            triggering_origin_id=fm_origin.resource_id,
            nodal_planes=NodalPlanes(
                nodal_plane_1=NodalPlane(strike=float(mt['strike1']),
                                         dip=float(mt['dip1']),
                                         rake=float(mt['rake1'])),
                nodal_plane_2=NodalPlane(strike=float(mt['strike2']),
                                         dip=float(mt['dip2']),
                                         rake=float(mt['rake2'])),
                preferred_plane=1),
            principal_axes=PrincipalAxes(
                t_axis=Axis(azimuth=float(mt['Taz']), plunge=float(mt['Tpl']),
                            length=mt['Tva']),
                p_axis=Axis(azimuth=float(mt['Paz']), plunge=float(mt['Ppl']),
                            length=mt['Pva']),
                n_axis=Axis(azimuth=float(mt['Naz']), plunge=float(mt['Npl']),
                            length=mt['Nva'])),
            station_polarity_count=int(mt['NS']),
            method_id=ResourceIdentifier("GNS_MT_solution"),
            moment_tensor=MomentTensor(
                derived_origin_id=fm_origin.resource_id,
                moment_magnitude_id=moment_mag.resource_id,
                scalar_moment=_dyne_cm_to_nm(float(mt['Mo'])),
                variance_reduction=float(mt['VR']),
                double_couple=float(mt['DC']) / 100,
                tensor=Tensor(
                    m_rr=_dyne_cm_to_nm(float(mt['Mxx']) * 1e20),
                    m_tt=_dyne_cm_to_nm(float(mt['Myy']) * 1e20),
                    m_pp=_dyne_cm_to_nm(float(mt['Mzz']) * 1e20),
                    m_rt=_dyne_cm_to_nm(float(mt['Mxy']) * 1e20),
                    m_rp=_dyne_cm_to_nm(float(mt['Mxz']) * 1e20),
                    m_tp=_dyne_cm_to_nm(float(mt['Myz']) * 1e20)),
                creation_info=CreationInfo(agency_id="GNS",
                                           author="John Ristau")))
        event.focal_mechanisms.append(fm)
    return catalog