def write_stream_to_sac(str1, write_dir='data', ext='', verbose=False):
if ext != '':
ext = '.' + ext
if not os.path.isdir(write_dir):
sys.exit('No such dir to write sac', write_dir)
for tr in str1:
sac = AttribDict()
(sac.kstnm, sac.knetwk, sac.kcmpnm,
sac.khole) = (str(tr.stats.station), str(tr.stats.network),
str(tr.stats.channel), str(tr.stats.location))
(sac.stla, sac.stlo,
sac.stel) = (tr.stats.station_coordinates.latitude,
tr.stats.station_coordinates.longitude,
tr.stats.station_coordinates.elevation)
ev = tr.stats.event_origin
time = ev.time
# sac depth is in km
sac.evla, sac.evlo, sac.evdp, sac.mag = ev.latitude, ev.longitude, ev.depth / 1000., tr.stats.event_mag.mag
sac.evla, sac.evlo, sac.evdp, sac.mag = ev.latitude, ev.longitude, ev.depth / 1000., tr.stats.event_mag.mag
# sac uses millisec while obspy uses microsec.
sac.nzyear, sac.nzjday, sac.nzhour, sac.nzmin, sac.nzsec, sac.nzmsec = time.year, time.julday, time.hour, time.minute, time.second, time.microsecond / 1000
sac.o = 0.
sac.b = tr.stats.starttime - time # this is very important!!
sac.kevnm = str(time)
# dip is from horizontal downward; inc is from vertical downward
# in SAC component "incidence angle" relative to the vertical
sac.cmpaz, sac.cmpinc = tr.stats.cmpaz, tr.stats.dip + 90
sac.gcarc, sac.dist, sac.az, sac.baz = tr.stats.gcarc, tr.stats.distance / 1000, tr.stats.azimuth, tr.stats.back_azimuth
# traveltimes
sac.a = tr.stats.Parr.arrival_time
sac.ka = 'P' # cannot add S time because user1 is assigned to ray parameter
# the ray parameter required by hk code is in sin(th)/v
(sac.user0, sac.user1) = (tr.stats.Parr.rayp / radiusOfEarth,
tr.stats.Sarr.rayp / radiusOfEarth)
# add sac header to tr.stats
tr.stats.sac = sac
# set sac file name
tr_name = write_dir + '/' + tr.stats.station + '.' + tr.stats.network + '.' + tr.stats.location + '.' + tr.stats.channel + ext + '.sac'
tr.write(tr_name, format='SAC')
if verbose:
print('Writing sac file ...' + tr_name)
def stream_add_stats(data_stream,inv,evt,write_sac=False,rotate_in_obspy=False):
for net in inv:
for sta in net:
str1=data_stream.select(network=net.code,station=sta.code)
print(str(net.code),str(sta.code),len(str1))
if len(str1) == 0:
continue
# update in future to deal with multiple channel (total_number_of channels)
if len(str1) % 3 !=0:
print('Problem: missing components', str1); exit()
for tr in str1:
for chan in sta:
if tr.stats.channel == chan.code and tr.stats.location == chan.location_code:
break
else:
print('Problem finding channel in inventory',tr); exit()
tr.stats.coordinates={'latitude':chan.latitude,'longitude':chan.longitude}
(tr.stats.distance,tr.stats.azimuth,tr.stats.back_azimuth)=gps2dist_azimuth(
chan.latitude, chan.longitude, evt.origins[0].latitude, evt.origins[0].longitude)
if write_sac==True:
sac= AttribDict()
sac.kstnm=str(sta.code);
sac.knetwk=str(net.code);
sac.kcmpnm=str(chan.code)
sac.khole=str(chan.location_code)
sac.stla=chan.latitude; sac.stlo=chan.longitude; sac.stel=chan.elevation
sac.evla=evt.origins[0].latitude; sac.evlo=evt.origins[0].longitude;
sac.evdp=evt.origins[0].depth/1000. # in km
sac.mag=evt.magnitudes[0].mag; time=evt.origins[0].time
sac.nzyear, sac.nzjday, sac.nzhour, sac.nzmin, sac.nzsec, sac.nzmsec=time.year, time.julday, time.hour, time.minute, time.second, time.microsecond/1000
sac.o=0.
sac.b=tr.stats.starttime-time # this is very important!!
sac.kevnm=str(time)
sac.cmpaz=chan.azimuth
# dip is from horizontal downward; inc is from vertical downward
sac.cmpinc=chan.dip+90
sac.gcarc = locations2degrees(evt.origins[0].latitude, evt.origins[0].longitude, chan.latitude, chan.longitude)
sac.dist,sac.az,sac.baz= tr.stats.distance/1000,tr.stats.azimuth,tr.stats.back_azimuth
tr.stats.sac=sac
tr_name=sta.code+'.'+net.code+'.'+chan.location_code+'.'+chan.code+'.sac'
tr.write(tr_name,format='SAC')
def RGF_from_SW4(path_to_green=".",
t0=0,
file_name=None,
origin_time=None,
event_lat=None,
event_lon=None,
depth=None,
station_name=None,
station_lat=None,
station_lon=None,
output_directory="sw4out"):
"""
Function to convert reciprocal Green's functions from SW4 to tensor format
Reads the reciprocal Green's functions (displacement/unit force) from SW4 and
performs the summation to get the Green's function tensor.
RGFs from SW4 are oriented north, east and positive down by setting az=0.
Assumes the following file structure:
f[x,y,z]/station_name/event_name.[x,y,z]
"""
import os
from obspy.core import read, Stream
from obspy.geodetics.base import gps2dist_azimuth
from obspy.core.util.attribdict import AttribDict
# Defined variables (do not change)
dirs = ["fz", "fx", "fy"] # directory to displacement per unit force
du = [
"duxdx", "duydy", "duzdz", "duydx", "duxdy", "duzdx", "duxdz", "duzdy",
"duydz"
]
orientation = ["Z", "N", "E"] # set az=0 in SW4 so x=north, y=east
cmpaz = [0, 0, 90]
cmpinc = [0, 90, 90]
# Create a new output directory under path_to_green
dirout = "%s/%s" % (path_to_green, output_directory)
if os.path.exists(dirout):
print("Warning: output directory '%s' already exists." % dirout)
else:
print("Creating output directory '%s'." % dirout)
os.mkdir(dirout)
# Loop over each directory fx, fy, fz
nsta = len(station_name)
for i in range(3):
# Set headers according to the orientation
if dirs[i][-1].upper() == "Z":
scale = -1 # change to positive up
else:
scale = 1
# Loop over each station
for j in range(nsta):
station = station_name[j]
stlo = station_lon[j]
stla = station_lat[j]
dirin = "%s/%s/%s" % (path_to_green, dirs[i], station)
print("Reading RGFs from %s:" % (dirin))
st = Stream()
for gradient in du:
fname = "%s/%s.%s" % (dirin, file_name, gradient)
st += read(fname, format="SAC")
# Set station headers
starttime = origin_time - t0
dist, az, baz = gps2dist_azimuth(event_lat, event_lon, stla, stlo)
# SAC headers
sacd = AttribDict()
sacd.stla = stla
sacd.stlo = stlo
sacd.evla = event_lat
sacd.evlo = event_lon
sacd.az = az
sacd.baz = baz
sacd.dist = dist / 1000 # convert to kilometers
sacd.o = 0
sacd.b = -1 * t0
sacd.cmpaz = cmpaz[i]
sacd.cmpinc = cmpinc[i]
sacd.kstnm = station
# Update start time
for tr in st:
tr.stats.starttime = starttime
tr.stats.distance = dist
tr.stats.back_azimuth = baz
# Sum displacement gradients to get reciprocal Green's functions
tensor = Stream()
for gradient, element in zip(["duxdx", "duydy", "duzdz"],
["XX", "YY", "ZZ"]):
trace = st.select(channel=gradient)[0].copy()
trace.stats.channel = "%s%s" % (orientation[i], element)
tensor += trace
trace = st.select(channel="duydx")[0].copy()
trace.data += st.select(channel="duxdy")[0].data
trace.stats.channel = "%s%s" % (orientation[i], "XY")
tensor += trace
trace = st.select(channel="duzdx")[0].copy()
trace.data += st.select(channel="duxdz")[0].data
trace.stats.channel = "%s%s" % (orientation[i], "XZ")
tensor += trace
trace = st.select(channel="duzdy")[0].copy()
trace.data += st.select(channel="duydz")[0].data
trace.stats.channel = "%s%s" % (orientation[i], "YZ")
tensor += trace
# Set sac headers before saving
print(" Saving GFs to %s" % dirout)
for tr in tensor:
tr.trim(origin_time, tr.stats.endtime)
tr.data = scale * tr.data
tr.stats.sac = sacd
sacout = "%s/%s.%.4f.%s" % (dirout, station, depth,
tr.stats.channel)
#print("Writing %s to file."%sacout)
tr.write(sacout, format="SAC")