def get_radial_transverse(self):
"""
Performs radial transverse rotation.
Returns:
radial_transverse: StationStream with the radial and
transverse components.
"""
st_copy = self.rotation_data.copy()
st_n = st_copy.select(component="[N1]")
st_e = st_copy.select(component="[E2]")
# Check that we have one northing and one easting channel
if len(st_e) != 1 or len(st_n) != 1:
raise Exception(
"Radial_Transverse: Stream must have one north and one east channel."
)
# Check that the orientations are orthogonal
ho1 = st_e[0].stats.standard.horizontal_orientation
ho2 = st_n[0].stats.standard.horizontal_orientation
if abs(ho1 - ho2) not in [90, 270]:
raise Exception("Radial_Transverse: Channels must be orthogonal.")
# Check that the lengths of the two channels are the same
if st_e[0].stats.npts != st_n[0].stats.npts:
raise Exception(
"Radial_Transverse: East and north channels must have same length."
)
# First, rotate to North-East components if not already
if st_n[0].stats.standard.horizontal_orientation != 0:
az_diff = 360 - st_n[0].stats.standard.horizontal_orientation
az_diff = np.deg2rad(az_diff)
rotation_matrix = np.array([
[np.cos(az_diff), np.sin(az_diff)],
[-np.sin(az_diff), np.cos(az_diff)],
])
data = np.array([st_n[0].data, st_e[0].data])
newdata = np.matmul(rotation_matrix, data)
st_n[0].data = newdata[0]
st_e[0].data = newdata[1]
st_n[0].stats.channel = st_n[0].stats.channel[:-1] + "N"
st_e[0].stats.channel = st_n[0].stats.channel[:-1] + "E"
# For some reason the rotation does not update the channel
# name in the rotation if it is not an obspy stream
ne_stream = Stream([st_n[0], st_e[0]])
# Calculate back azimuth and perform rotation to radial and transverse
baz = gps2dist_azimuth(
st_e[0].stats.coordinates.latitude,
st_e[0].stats.coordinates.longitude,
self.event.latitude,
self.event.longitude,
)[1]
ne_stream.rotate(method="NE->RT", back_azimuth=baz)
radial_transverse = StationStream([ne_stream[0], ne_stream[1]])
return radial_transverse
try:
#search for N/1 channel with high-frequency response
inv=irisclient.get_stations(starttime=starttime,endtime=endtime,station=st,level="channel",channel="BHN,BH1,HHN,HH1,SHN,SH1")
#find appropriate channels in the inventory (ASDF returns list, not inventory type)
chan=inv.get_contents()['channels'][0].split('.')
stream=irisclient.get_waveforms(chan[0],chan[1],chan[2],chan[3],starttime,endtime)
wf1=stream[0]
if wf1.stats['channel'][-1] == '1':
wf2=irisclient.get_waveforms(chan[0],chan[1],chan[2],chan[3][0:-1]+'2',starttime,endtime)[0]
wfz=irisclient.get_waveforms(chan[0],chan[1],chan[2],chan[3][0:-1]+'Z',starttime,endtime)[0]
stream=Stream(traces=[wfz,wf1,wf2])
#get an inventory including the Z and E/2 channels
IRISinv=irisclient.get_stations(starttime=starttime,endtime=endtime,station=st,level="channel")
stream=stream.rotate(method="->ZNE",inventory=IRISinv)
else:
wf2=irisclient.get_waveforms(chan[0],chan[1],chan[2],chan[3][0:-1]+'E',starttime,endtime)[0]
stream=Stream(traces=[wf1,wf2])
stream=stream.rotate(method="NE->RT",back_azimuth=baz)
wf=None
for trywf in stream:
if trywf.stats['channel'][-1]=='T':
wf=trywf
break
if wf and len(wf)>100:
wf.resample(100)
wf.detrend()
wf.normalize()
wf.write(saveDir+str(wfctr)+'_S.pkl',format="PICKLE")
def _getData(pick, fds, ic):
if pick[0][0] == '#': #this line is commented
return None
net = pick[6]
st = pick[7]
ch = pick[8]
time = UTCDateTime(float(pick[9]))
starttime = time - 20
endtime = time + 40
if ch == '00T':
baz = float(pick[14])
#get all the horizontal short-period channels at loc '00' or '' (assuming the 00 in 00T refers to
#loc)
try:
inv = fds.get_stations(starttime, endtime, network=net, station=st)
#find appropriate channels in the inventory (ASDF returns list, not inventory type)
for chan in inv:
if re.search('^[HBS].[N1]$', chan[3]):
break
if not re.search('^[HBS].[N1]$', chan[3]):
raise Exception('no appropriate horizontal channels found')
stream = fds.get_waveforms(net, st, chan[2], chan[3], starttime,
endtime)
wf1 = stream[0]
if wf1.stats['channel'][-1] == '1':
wf2 = fds.get_waveforms(net, st, chan[2], chan[3][0:-1] + '2',
starttime, endtime)[0]
wfz = fds.get_waveforms(net, st, chan[2], chan[3][0:-1] + 'Z',
starttime, endtime)[0]
stream = Stream(traces=[wfz, wf1, wf2])
#this is a necessary hack - ASDF inventories do not have orientation data for
#the 1 and 2 channels so it is impossible to rotate to ZNE accurately. Therefore
#we get station data off IRIS. All the OA installations have ZNE data provided,
#so only the permanent stations need to rotate 12->NE, and being permanent they should
#have metadata available through IRIS.
IRISinv = ic.get_stations(network=net,
station=st,
channel=ch,
level="channel")
stream = stream.rotate(method="->ZNE", inventory=IRISinv)
else:
wf2 = fds.get_waveforms(net, st, chan[2], chan[3][0:-1] + 'E',
starttime, endtime)[0]
stream = Stream(traces=[wf1, wf2])
except Exception as e:
#handle data missing
print >> sys.stderr, e
stream = None
wf = None
if stream:
try:
stream = stream.rotate(method='NE->RT', back_azimuth=baz)
for trywf in stream:
if trywf.stats['channel'][-1] == 'T':
wf = trywf
break
except Exception as e:
print >> sys.stderr, e
wf = None
else:
try:
#just grab the channel that the pick was on
inv = fds.get_stations(starttime,
endtime,
network=net,
station=st,
channel=ch)
loc = inv[0][2]
wf = fds.get_waveforms(net, st, loc, ch, starttime, endtime)[0]
except Exception as e:
print >> sys.stderr, e
wf = None
if wf and len(wf) > 100:
wf.resample(100)
wf.detrend()
wf.normalize()
return wf.data
else:
print >> sys.stderr, 'Waveform not found. Skipping pick...'
return None
def _getData(pick,fds,mintime):
if pick[0][0]=='#': #this line is commented
return None
net=pick[6]
st=pick[7]
ch=pick[8]
time=UTCDateTime(float(pick[9]))
if mintime:
if time < mintime:
return None
starttime=time-20
endtime=time+40
if ch=='00T':
baz=float(pick[14])
#get all the horizontal short-period channels at loc '00' or '' (assuming the 00 in 00T refers to
#loc)
try:
inv=fds.get_stations(starttime,endtime,network=net,station=st)
#find appropriate channels in the inventory (ASDF returns list, not inventory type)
for chan in inv:
if re.search('^[HBS].[N1]$',chan[3]):
break
if not re.search('^[HBS].[N1]$',chan[3]):
raise Exception('no appropriate horizontal channels found')
stream=fds.get_waveforms(net,st,chan[2],chan[3],starttime,endtime)
wf1=stream[0]
wf2=fds.get_waveforms(net,st,chan[2],chan[3][0:-1]+'E',starttime,endtime)[0]
#this is a hack and wrong. Hopefully 1 and 2 are only off from N and E by a few degrees max
wf1.id=wf1.id[:-1]+'N'
wf2.id=wf2.id[:-1]+'E'
stream=Stream(traces=[wf1,wf2])
except Exception as e:
#handle data missing
print >> sys.stderr, e
stream=None
wf=None
if stream:
try:
stream=stream.rotate(method='NE->RT',back_azimuth=baz)
for trywf in stream:
if trywf.stats['channel'][-1]=='T':
wf=trywf
break
except Exception as e:
print >>sys.stderr, e
wf=None
else:
try:
#just grab the channel that the pick was on
inv=fds.get_stations(starttime,endtime,network=net,station=st,channel=ch)
loc=inv[0][2]
wf=fds.get_waveforms(net,st,loc,ch,starttime,endtime)[0]
except Exception as e:
print >> sys.stderr, e
wf=None
if wf and len(wf)>100:
wf.resample(100)
wf.detrend()
wf.normalize()
return wf.data
else:
print >> sys.stderr, 'Waveform not found. Skipping pick...'
return None
station_longitude = 12.8782
# theoretical backazimuth and distance
baz = gps2dist_azimuth(source_latitude, source_longitude, station_latitude, station_longitude)
print('Epicentral distance [m]: ',baz[0])
print('Theoretical azimuth [deg]: ', baz[1])
print('Theoretical backazimuth [deg]: ', baz[2])
# rotate E-N component seismometer recordings to radial[1]-transverse[0] components using the theoretical BAz
AC_original = AC.copy()
#normalize
AC_original.normalize()
RLAS.normalize()
AC.normalize()
AC.rotate(method='NE->RT',back_azimuth=baz[2])
sampling_rate = int(RLAS[0].stats.sampling_rate)
time = np.linspace(0, len(AC[0].data)/sampling_rate,len(AC[0].data))
# **Estimate correlation coefficients for different time windows and estimate BAZ**
# In[5]:
TauPy_model = TauPyModel('ak135')
arrivals_p = TauPy_model.get_travel_times(distance_in_degree=0.001 * baz[0] / 111.11,
source_depth_in_km=event.origins[0].depth*0.001,
phase_list=["P","p","Pdiff","PP","PKiKP","PKIKP","Pn","Pg"])
print('Epicentral distance [m]: ', baz[0])
print('Theoretical azimuth [deg]: ', baz[1])
print('Theoretical backazimuth [deg]: ', baz[2])
# -
# We now rotate the E-N component seismometer recordings to radial [0] and transverse [1] acceleration using the theoretical BAz.<br>
#
# In a last step the normalized **transverse acceleration** is plotted together with <font color='red'>**vertical rotation rate**</font>.
# +
from obspy.signal.rotate import rotate_ne_rt
import numpy as np
# rotate
AC.rotate(method='NE->RT',back_azimuth=baz[2])
plt.figure(figsize=(15,2))
ax = plt.subplot(111)
ax.plot(RLAS[0].times(), RLAS[0].data/np.max(np.abs(RLAS[0].data)), 'r', label='vertical rotation rate')
ax.plot(AC[0].times(), AC[0].data/np.max(np.abs(AC[0].data)), 'k', label='transverse acceleration')
ax.legend(loc=2, prop={"size":12})
ax.set_xlabel('time [s]')
ax.set_ylabel('normalized amplitude')
ax.set_xlim(0,max(RLAS[0].times()))
plt.show()
# -
# **<big>Note: the vertical rotation rate and transverse acceleration are in phase!</big>**
