def afteran_decluster(
    catalogue_matrix, window_opt=TDW_GARDNERKNOPOFF, time_window=60.):
    '''AFTERAN declustering algorithm.
    ||(Musson, 1999, "Probabilistic Seismic Hazard Maps for the North Balkan
       region", Annali di Geofisica, 42(6), 1109 - 1124) ||
    :param catalog_matrix: eq catalog in a matrix format with these columns in
                            order: `year`, `month`, `day`, `longitude`,
                            `latitude`, `Mw`
    :type catalog_matrix: numpy.ndarray
    :keyword window_opt: method used in calculating distance and time windows
    :type window_opt: string
    :keyword time_window: Length (in days) of moving time window
    :type time_window: positive float
    :returns: **vcl vector** indicating cluster number, **vmain_shock catalog**
              containing non-clustered events, **flagvector** indicating
              which eq events belong to a cluster
    :rtype: numpy.ndarray
    '''

    #Convert time window from days to decimal years
    time_window = time_window / 365.

    # Pre-processing steps are the same as for Gardner & Knopoff
    # Get relevent parameters
    mag = catalogue_matrix[:, 5]

    neq = np.shape(catalogue_matrix)[0]  # Number of earthquakes
    # Get decimal year (needed for time windows)
    year_dec = decimal_year(catalogue_matrix[:, 0], catalogue_matrix[:, 1],
                            catalogue_matrix[:, 2])

    # Get space windows corresponding to each event
    sw_space = time_dist_windows[window_opt].calc(mag)[0]

    eqid = np.arange(0, neq, 1)  # Initial Position Identifier

    # Pre-allocate cluster index vectors
    vcl = np.zeros((neq, 1), dtype=int)
    flagvector = np.zeros((neq, 1), dtype=int)
    # Sort magnitudes into descending order
    id0 = np.flipud(np.argsort(mag, kind='heapsort'))
    mag = mag[id0]
    catalogue_matrix = catalogue_matrix[id0, :]
    sw_space = sw_space[id0]
    year_dec = year_dec[id0]
    eqid = eqid[id0]

    i = 0
    clust_index = 0
    while i < neq:
        if vcl[i] == 0:
            # Earthquake not allocated to cluster - perform calculation
            # Perform distance calculation
            mdist = haversine(catalogue_matrix[:, 3], catalogue_matrix[:, 4],
                          catalogue_matrix[i, 3], catalogue_matrix[i, 4])

            # Select earthquakes inside distance window and not in cluster
            vsel = np.logical_and(mdist <= sw_space[i], vcl == 0).flatten()
            dtime = year_dec[vsel] - year_dec[i]

            nval = np.shape(dtime)[0]  # Number of events inside valid window
            # Pre-allocate boolean array (all True)

            vsel1 = _find_aftershocks(dtime, nval, time_window)
            vsel2 = _find_foreshocks(dtime, nval, time_window, vsel1)

            temp_vsel = np.copy(vsel)
            temp_vsel[vsel] = np.logical_or(vsel1, vsel2)
            if np.shape(np.nonzero(temp_vsel)[0])[0] > 1:
                # Contains clustered events - allocate a cluster index
                vcl[temp_vsel] = clust_index + 1
                # Remove mainshock from cluster
                vsel1[0] = False
                # Assign markers to aftershocks and foreshocks
                temp_vsel = np.copy(vsel)
                temp_vsel[vsel] = vsel1
                flagvector[temp_vsel] = 1
                vsel[vsel] = vsel2
                flagvector[vsel] = -1
                clust_index += 1
        i += 1

    # Now have events - re-sort array back into chronological order
    # Re-sort the data into original order
    id1 = np.argsort(eqid, kind='heapsort')
    eqid = eqid[id1]
    catalogue_matrix = catalogue_matrix[id1, :]
    vcl = vcl[id1]
    flagvector = flagvector[id1]

    # Now to produce a catalogue with aftershocks purged
    vmain_shock = catalogue_matrix[np.nonzero(flagvector == 0)[0], :]

    return vcl.flatten(), vmain_shock, flagvector.flatten()
Exemplo n.º 2
0
def afteran_decluster(catalogue_matrix,
                      window_opt=TDW_GARDNERKNOPOFF,
                      time_window=60.):
    '''AFTERAN declustering algorithm.
    ||(Musson, 1999, "Probabilistic Seismic Hazard Maps for the North Balkan
       region", Annali di Geofisica, 42(6), 1109 - 1124) ||
    :param catalog_matrix: eq catalog in a matrix format with these columns in
                            order: `year`, `month`, `day`, `longitude`,
                            `latitude`, `Mw`
    :type catalog_matrix: numpy.ndarray
    :keyword window_opt: method used in calculating distance and time windows
    :type window_opt: string
    :keyword time_window: Length (in days) of moving time window
    :type time_window: positive float
    :returns: **vcl vector** indicating cluster number, **vmain_shock catalog**
              containing non-clustered events, **flagvector** indicating
              which eq events belong to a cluster
    :rtype: numpy.ndarray
    '''

    #Convert time window from days to decimal years
    time_window = time_window / 365.

    # Pre-processing steps are the same as for Gardner & Knopoff
    # Get relevent parameters
    mag = catalogue_matrix[:, 5]

    neq = np.shape(catalogue_matrix)[0]  # Number of earthquakes
    # Get decimal year (needed for time windows)
    year_dec = decimal_year(catalogue_matrix[:, 0], catalogue_matrix[:, 1],
                            catalogue_matrix[:, 2])

    # Get space windows corresponding to each event
    sw_space = time_dist_windows[window_opt].calc(mag)[0]

    eqid = np.arange(0, neq, 1)  # Initial Position Identifier

    # Pre-allocate cluster index vectors
    vcl = np.zeros((neq, 1), dtype=int)
    flagvector = np.zeros((neq, 1), dtype=int)
    # Sort magnitudes into descending order
    id0 = np.flipud(np.argsort(mag, kind='heapsort'))
    mag = mag[id0]
    catalogue_matrix = catalogue_matrix[id0, :]
    sw_space = sw_space[id0]
    year_dec = year_dec[id0]
    eqid = eqid[id0]

    i = 0
    clust_index = 0
    while i < neq:
        if vcl[i] == 0:
            # Earthquake not allocated to cluster - perform calculation
            # Perform distance calculation
            mdist = haversine(catalogue_matrix[:, 3], catalogue_matrix[:, 4],
                              catalogue_matrix[i, 3], catalogue_matrix[i, 4])

            # Select earthquakes inside distance window and not in cluster
            vsel = np.logical_and(mdist <= sw_space[i], vcl == 0).flatten()
            dtime = year_dec[vsel] - year_dec[i]

            nval = np.shape(dtime)[0]  # Number of events inside valid window
            # Pre-allocate boolean array (all True)

            vsel1 = _find_aftershocks(dtime, nval, time_window)
            vsel2 = _find_foreshocks(dtime, nval, time_window, vsel1)

            temp_vsel = np.copy(vsel)
            temp_vsel[vsel] = np.logical_or(vsel1, vsel2)
            if np.shape(np.nonzero(temp_vsel)[0])[0] > 1:
                # Contains clustered events - allocate a cluster index
                vcl[temp_vsel] = clust_index + 1
                # Remove mainshock from cluster
                vsel1[0] = False
                # Assign markers to aftershocks and foreshocks
                temp_vsel = np.copy(vsel)
                temp_vsel[vsel] = vsel1
                flagvector[temp_vsel] = 1
                vsel[vsel] = vsel2
                flagvector[vsel] = -1
                clust_index += 1
        i += 1

    # Now have events - re-sort array back into chronological order
    # Re-sort the data into original order
    id1 = np.argsort(eqid, kind='heapsort')
    eqid = eqid[id1]
    catalogue_matrix = catalogue_matrix[id1, :]
    vcl = vcl[id1]
    flagvector = flagvector[id1]

    # Now to produce a catalogue with aftershocks purged
    vmain_shock = catalogue_matrix[np.nonzero(flagvector == 0)[0], :]

    return vcl.flatten(), vmain_shock, flagvector.flatten()
def gardner_knopoff_decluster(
    catalog_matrix, window_opt=TDW_GARDNERKNOPOFF, fs_time_prop=0):
    """
    Gardner Knopoff algorithm.

    :param catalog_matrix: eq catalog in a matrix format with these columns in
                            order: `year`, `month`, `day`, `longitude`,
                            `latitude`, `Mw`
    :type catalog_matrix: numpy.ndarray
    :keyword window_opt: method used in calculating distance and time windows
    :type window_opt: string
    :keyword fs_time_prop: foreshock time window as a proportion of
                           aftershock time window
    :type fs_time_prop: positive float
    :returns: **vcl vector** indicating cluster number, **vmain_shock catalog**
              containing non-clustered events, **flagvector** indicating
              which eq events belong to a cluster
    :rtype: numpy.ndarray
    """

    # Get relevent parameters
    m = catalog_matrix[:, 5]
    neq = np.shape(catalog_matrix)[0]  # Number of earthquakes
    # Get decimal year (needed for time windows)
    year_dec = decimal_year(
        catalog_matrix[:, 0], catalog_matrix[:, 1], catalog_matrix[:, 2])
    # Get space and time windows corresponding to each event
    sw_space, sw_time = time_dist_windows[window_opt].calc(m)
    eqid = np.arange(0, neq, 1)  # Initial Position Identifier

    # Pre-allocate cluster index vectors
    vcl = np.zeros(neq, dtype=int)

    # Sort magnitudes into descending order
    id0 = np.flipud(np.argsort(m, kind='heapsort'))
    m = m[id0]
    catalog_matrix = catalog_matrix[id0, :]
    sw_space = sw_space[id0]
    sw_time = sw_time[id0]
    year_dec = year_dec[id0]
    eqid = eqid[id0]
    flagvector = np.zeros(neq, dtype=int)
    #Begin cluster identification
    clust_index = 0
    for i in range(0, neq - 1):
        if vcl[i] == 0:
            # Find Events inside both fore- and aftershock time windows
            dt = year_dec - year_dec[i]
            vsel = np.logical_and(dt >= (-sw_time[i] * fs_time_prop),
                                              dt <= sw_time[i],
                                              flagvector == 0)
            # Of those events inside time window, find those inside distance
            # window
            vsel1 = haversine(
                catalog_matrix[vsel, 3], catalog_matrix[vsel, 4],
                catalog_matrix[i, 3], catalog_matrix[i, 4]) <= sw_space[i]
            vsel[vsel] = vsel1
            temp_vsel = np.copy(vsel)
            temp_vsel[i] = False
            if any(temp_vsel):
                # Allocate a cluster number
                vcl[vsel] = clust_index + 1
                flagvector[vsel] = 1
                # For those events in the cluster before the main event,
                # flagvector is equal to -1
                temp_vsel[dt >= 0.0] = False
                flagvector[temp_vsel] = -1
                flagvector[i] = 0
                clust_index += 1

    # Re-sort the catalog_matrix into original order
    id1 = np.argsort(eqid, kind='heapsort')
    eqid = eqid[id1]
    catalog_matrix = catalog_matrix[id1, :]
    vcl = vcl[id1]
    flagvector = flagvector[id1]
    # Now to produce a catalogue with aftershocks purged
    vmain_shock = catalog_matrix[np.nonzero(flagvector == 0)[0], :]

    return vcl, vmain_shock, flagvector
Exemplo n.º 4
0
def gardner_knopoff_decluster(catalog_matrix,
                              window_opt=TDW_GARDNERKNOPOFF,
                              fs_time_prop=0):
    """
    Gardner Knopoff algorithm.

    :param catalog_matrix: eq catalog in a matrix format with these columns in
                            order: `year`, `month`, `day`, `longitude`,
                            `latitude`, `Mw`
    :type catalog_matrix: numpy.ndarray
    :keyword window_opt: method used in calculating distance and time windows
    :type window_opt: string
    :keyword fs_time_prop: foreshock time window as a proportion of
                           aftershock time window
    :type fs_time_prop: positive float
    :returns: **vcl vector** indicating cluster number, **vmain_shock catalog**
              containing non-clustered events, **flagvector** indicating
              which eq events belong to a cluster
    :rtype: numpy.ndarray
    """

    # Get relevent parameters
    m = catalog_matrix[:, 5]
    neq = np.shape(catalog_matrix)[0]  # Number of earthquakes
    # Get decimal year (needed for time windows)
    year_dec = decimal_year(catalog_matrix[:, 0], catalog_matrix[:, 1],
                            catalog_matrix[:, 2])
    # Get space and time windows corresponding to each event
    sw_space, sw_time = time_dist_windows[window_opt].calc(m)
    eqid = np.arange(0, neq, 1)  # Initial Position Identifier

    # Pre-allocate cluster index vectors
    vcl = np.zeros(neq, dtype=int)

    # Sort magnitudes into descending order
    id0 = np.flipud(np.argsort(m, kind='heapsort'))
    m = m[id0]
    catalog_matrix = catalog_matrix[id0, :]
    sw_space = sw_space[id0]
    sw_time = sw_time[id0]
    year_dec = year_dec[id0]
    eqid = eqid[id0]
    flagvector = np.zeros(neq, dtype=int)
    #Begin cluster identification
    clust_index = 0
    for i in range(0, neq - 1):
        if vcl[i] == 0:
            # Find Events inside both fore- and aftershock time windows
            dt = year_dec - year_dec[i]
            vsel = np.logical_and(dt >= (-sw_time[i] * fs_time_prop),
                                  dt <= sw_time[i], flagvector == 0)
            # Of those events inside time window, find those inside distance
            # window
            vsel1 = haversine(catalog_matrix[vsel, 3], catalog_matrix[vsel, 4],
                              catalog_matrix[i, 3],
                              catalog_matrix[i, 4]) <= sw_space[i]
            vsel[vsel] = vsel1
            temp_vsel = np.copy(vsel)
            temp_vsel[i] = False
            if any(temp_vsel):
                # Allocate a cluster number
                vcl[vsel] = clust_index + 1
                flagvector[vsel] = 1
                # For those events in the cluster before the main event,
                # flagvector is equal to -1
                temp_vsel[dt >= 0.0] = False
                flagvector[temp_vsel] = -1
                flagvector[i] = 0
                clust_index += 1

    # Re-sort the catalog_matrix into original order
    id1 = np.argsort(eqid, kind='heapsort')
    eqid = eqid[id1]
    catalog_matrix = catalog_matrix[id1, :]
    vcl = vcl[id1]
    flagvector = flagvector[id1]
    # Now to produce a catalogue with aftershocks purged
    vmain_shock = catalog_matrix[np.nonzero(flagvector == 0)[0], :]

    return vcl, vmain_shock, flagvector