(8) One year (2018) of Pacific seismicity events — GMT 6.4.0 documentation

# (8) One year (2018) of Pacific seismicity events

Animation of all seismicity in the Pacific basin during 2018 that exceeded a threshold of magnitude 5. We then plot the earthquakes as they occurred on a map that moves in longitude from west to east, with a deliberate pause near Longitude 200 so we can watch the near-daily magnitude 5.2 quakes that hit the Big Island of Hawaii during the 3-month 2018 eruption. We scale magnitude to symbol size (spherical circle diameter in km) and announce each quake by magnifying size and whitening the color for a little bit. Later the symbols fade to darker color and smaller sizes but remain for the duration of the movie.

- DEM: @earth_relief_02m

- Line: ridge.txt

The resulting movie was presented at the Fall 2019 AGU meeting in an eLighting talk: P. Wessel, 2019, GMT science animations for the masses, Abstract IN21B-11. The finished movie is available in our YouTube channel as well: https://youtu.be/H0RyjHRhJ3g.

The movie took ~1 hour to render on a 24-core MacPro 2013.

    #!/usr/bin/env bash
    #
    # Animation of all seismicity in the Pacific basin during 2018 that exceeded
    # a threshold of magnitude 5.  We then plot the earthquakes as they occurred on
    # a map that moves in longitude from west to east, with a deliberate pause near
    # Longitude 200 so we can watch the near-daily magnitude 5.2 quakes that hit the
    # Big Island of Hawaii during the 3-month 2018 eruption.  We scale magnitude to
    # symbol size (spherical circle diameter in km) and announce each quake by magnifying
    # size and whitening the color for a little bit.  Later the symbols fade to darker
    # color and smaller sizes but remain for the duration of the movie.
    # DEM:   @earth_relief_02m
    # Line:  ridge.txt
    # The resulting movie was presented at the Fall 2019 AGU meeting in an eLighting talk:
    # P. Wessel, 2019, GMT science animations for the masses, Abstract IN21B-11.
    # The finished movie is available in our YouTube channel as well:
    # https://youtu.be/H0RyjHRhJ3g
    # The movie took ~1 hour to render on a 24-core MacPro 2013.

    # 1. Extract 2018 data >= Mag 5 from URL and prepare inputs and frame times
    cat << 'EOF' > pre.sh
    SITE="https://earthquake.usgs.gov/fdsnws/event/1/query.csv"
    TIME="starttime=2018-01-01%2000:00:00&endtime=2018-12-31%2000:00:00"
    MAG="minmagnitude=5"
    ORDER="orderby=time-asc"
    URL="${SITE}?${TIME}&${MAG}&${ORDER}"
    gmt begin
    	# Get seismicity and scale magnitude by 50 to give symbol size in km
    	gmt convert $URL -i2,1,3,4+s50,0 -hi1 > q.txt
    	# Create standard seismicity cpt
    	gmt makecpt -Cred,green,blue -T0,70,300,10000 -H > q.cpt
    	# Make lons go from 160 to 240 with a pause at 200 mid movie
    	cat <<- EOF | gmt sample1d -fT --TIME_UNIT=d -I1 -Fa > times.txt
    	2018-01-01T	160
    	2018-05-01T	200
    	2018-06-01T	200
    	2018-07-01T	200
    	2018-08-01T	200
    	2018-12-31T	240
    	EOF
        # Get gradients of the relief from N45E
        gmt grdgradient @earth_relief_02m -Nt1.2 -A45 -Gintens.nc
    	gmt makecpt -Cterra -T-10000/8000 -H > t.cpt
    gmt end
    EOF
    # 2. Set up main script
    cat << 'EOF' > main.sh
    gmt begin
    	# Let HSV minimum value go to zero
    	gmt set COLOR_HSV_MIN_V 0
    	# Fake simulation of sun illumination from east combined with relief slopes
    	gmt grdmath intens.nc X ${MOVIE_COL1} SUB DUP -180 LE 360 MUL ADD 90 DIV ERF ADD 0.5 SUB = s.nc
    	# Overlay relief over land only using dem cpt
    	gmt grdimage @earth_relief_02m -Is.nc -Ct.cpt -JG${MOVIE_COL1}/5/18c -X0 -Y0
    	# Plot the mid-ocean ridge line
    	gmt plot @ridge.txt -W0.5p,darkyellow
    	# Plot seismicity at this time according to visibility and enhancement settings
    	gmt events q.txt -SE- -Cq.cpt --TIME_UNIT=d -T${MOVIE_COL0} -Es+r2+d6 -Ms5+c0.5 -Mi1+c-0.6 -Mt+c0
    gmt end
    EOF
    # 3. Run the movie at 24 frames/sec at 60 dpc to give 1080x1080 size, each frame represent one day
    gmt movie main.sh -Sbpre.sh -C18cx18cx60 -Ttimes.txt -Nanim08 -H8 -Lc0 -M150,png -Fmp4 -G30 -V -W -Zs \
    	--FONT_TAG=20p,Helvetica,white --FORMAT_CLOCK_MAP=-