Prepare one AxiSEM injection event

axisemlib prepare converts a geographic CMTSOLUTION and STATIONS file to geocentric latitudes and sets the time and wavefield region parameters for one event. It writes the four solver input files and does not start a simulation.

Example geographic inputs

Example CMTSOLUTION:

 PDEW2015  8 10  7 43 37.30 -19.6400 -174.8500  46.3 0.0 5.6 TONGA ISLANDS
event name:     201508100743A
time shift:      8.9700
half duration:   1.6000
latitude:      -19.6200
longitude:    -174.4700
depth:         109.3700
Mrr:      -4.480000e+23
Mtt:       1.590000e+24
Mpp:      -1.140000e+24
Mrt:      -9.660000e+22
Mrp:      -3.650000e+24
Mtp:      -1.960000e+23

Example STATIONS (ten rows):

CDT BU 41.015300 117.915800 117.900000 0.
SHZ HL 44.062000 128.956000 330.000000 0.
BNX HL 45.739000 127.403000 165.000000 0.
BST JL 41.945200 126.368500 551.900000 0.
QAT JL 45.006100 124.004000 164.400000 0.
CBS JL 42.070000 128.070000 1790.000000 0.
PST JL 42.950100 126.078000 408.800000 0.
SPT JL 43.199700 124.534900 256.600000 0.
SMT JL 42.188200 128.174000 1149.000000 0.
WQT JL 43.690000 129.010000 358.000000 0.

The station columns are name, network, geographic latitude, longitude, elevation in metres, and burial depth in metres. A STATIONS file contains one such row per station. The preparation script converts the centroid latitude: and each station latitude to geocentric coordinates.

Run from the solver directory

Install AxiSEMLib first. Prepare the mesh and the event’s geographic source and station files, then run the command from the solver’s SOLVER directory:

cd ../axisem/SOLVER
axisemlib prepare \
    --region-box 114 132 41 46 450 \
    --t0-injection 1166.926174 \
    --cmtsolution CMT_DIR/CMTSOLUTION_SKS_1 \
    --stations CMT_DIR/STATIONS_SKS_1

--region-box requires five values: minimum and maximum longitude, minimum and maximum geographic latitude (degrees), and maximum depth (km). The example study region spans 114–132° longitude, 41–46° latitude, and 0–450 km depth. --t0-injection is the event’s injection arrival time in seconds on the solver’s time axis.

The script writes CMTSOLUTION, STATIONS, inparam_basic, and inparam_advanced directly into the current directory by default. It reads all inputs before writing. The source CMTSOLUTION and STATIONS paths must differ from their output paths, which prevents converting an already converted latitude again. Working inparam_basic and inparam_advanced files in the output directory are updated in place when used as the inputs. Each invocation replaces any existing output files with these four names.

After checking the prepared files, start the event explicitly:

./submit.csh ak135.SKS_1

If SAVE_BDRY_FACES is enabled, place boundary_faces.dat in SOLVER before calling submit.csh.

Input paths and optional buffers

Option	Default	Purpose
--region-box LON_MIN LON_MAX LAT_MIN LAT_MAX MAX_DEPTH_KM	Required	Geographic study region
--t0-injection SECONDS	Required	Injection arrival time
--cmtsolution PATH	CMT_DIR/CMTSOLUTION	Geographic event source file
--stations PATH	CMT_DIR/STATIONS	Geographic station file
--inparam-basic PATH	inparam_basic	Basic parameter input
--inparam-advanced PATH	inparam_advanced	Advanced parameter input
--output-dir PATH	.	Destination for the four solver input files
--pre-buffer-seconds SECONDS	50	Start dumping this long before injection
--post-buffer-seconds SECONDS	300	End the simulation this long after injection
--region-buffer-deg DEGREES	10	Add this margin to both angular bounds

The default CMT_DIR/CMTSOLUTION and CMT_DIR/STATIONS names are generic input paths. Pass the event-specific paths, as in the example, when your source directory contains names such as CMTSOLUTION_SKS_1 and STATIONS_SKS_1.

For a narrower time and angular window, append:

--pre-buffer-seconds 40 --post-buffer-seconds 250 --region-buffer-deg 5

All buffer sizes must be nonnegative. The injection time must be at least the pre-injection buffer, so DUMP_T0 is not negative.

What the script changes

The output CMTSOLUTION uses a geocentric latitude: value. The latitude in each data row of STATIONS is also converted to geocentric degrees. The geographic input files are left unchanged when they are separate from the output paths.

The parameter values are calculated as follows:

Parameter	Value
DUMP_T0	t0_injection - pre_buffer_seconds
SEISMOGRAM_LENGTH	t0_injection + post_buffer_seconds
KERNEL_COLAT_MIN	Minimum event-to-region epicentral distance minus region_buffer_deg
KERNEL_COLAT_MAX	Maximum event-to-region epicentral distance plus region_buffer_deg
KERNEL_RMIN	6371 - MAX_DEPTH_KM
KERNEL_RMAX	7000 km

The angular limits come from a 100 × 100 sample of the geographic region after its latitudes are converted to geocentric coordinates. If the advanced parameter input has no DUMP_T0 line, the script inserts it after KERNEL_SPP.

Use --output-dir to prepare files outside SOLVER. To submit that event, copy the four prepared files into SOLVER before running submit.csh; the solver submission script reads its inputs from that directory.