Waveform plot¶

This will download continuous seismic waveforms & plot them and requires ObsPy

Import ObsPy module¶

from obspy import read
from obspy import UTCDateTime
from obspy.clients.fdsn import Client

import obspy as ob
print("# obspy version = ",ob.__version__)

# obspy version =  1.2.2

Set client (Data Center)¶

This example uses NCEDC. We can use other dataceneter (e.g., SCEDC, IRIS)

client = Client("NCEDC") # data from NCEDC 
#client = Client("SCEDC") # data from SCEDC
#client = Client("IRIS") # data from IRIS

Set SNCL¶

Which SNCL (Station, Network, Component, Location)? This example uses BRK.BK.HHZ.00 data

# BRK BHZ data (https://seismo.berkeley.edu/station_book/brk.html; Haviland Hall)
sta = "BRK" # station
com = "HHZ" # component 
net = "BK" # network
loc = "00" # location "--" for blank location code

Set time window¶

This example uses 1-min data for the 2020 M3.1 Alum Rock earthquake

# Alum Rock event
#M 3.1 - 8km NE of Alum Rock, CA
#2020-08-02 12:40:24 (UTC)37.409°N 121.755°W7.9 km depth
start_day = "2020-08-02T12:40:24"
end_day = "2020-08-02T12:41:24"
starttime = UTCDateTime(start_day)
endtime = UTCDateTime(end_day)

Download seismic data¶

use get_waveforms to download data and do st.plot() for plotting

st = client.get_waveforms(network=net, station=sta, location=loc, channel=com,
                     starttime=starttime, endtime=endtime, 
                     attach_response=True)
_plot = st.plot()

Correct instrument response¶

use remove_response to correct the instrument response. We can select output unit (displacement, velocity or accerelation)

st.detrend() # remove liner trend
st.taper(max_percentage=0.001) # apply taper

1 Trace(s) in Stream:
BK.BRK.00.HHZ | 2020-08-02T12:40:24.008393Z - 2020-08-02T12:41:23.998393Z | 100.0 Hz, 6000 samples

st = st.remove_response( output="VEL" ) # get velocity data (m/s)
#st = st.remove_response( output="DISP" ) # get displacement data (m)
#st = st.remove_response( output="ACC" ) # get acceleration data (m/s^2)

_plot = st.plot()

Filtering seismic data¶

first remove liner trend, apply a cosin taper, and then do filtering

fl = 5 # in Hz 
fh = 10 # in Hz
st.filter(type='bandpass', freqmin=fl, freqmax=fh, corners=6, zerophase=False)

1 Trace(s) in Stream:
BK.BRK.00.HHZ | 2020-08-02T12:40:24.008393Z - 2020-08-02T12:41:23.998393Z | 100.0 Hz, 6000 samples

_plot = st.plot()