You may encounter situations where a specific ASCII format is
required, and your data cannot be used in its native ASCII format.
With newform, you can easily reformat one ASCII format to
another. In this example, you will reformat California earthquake data
from one ASCII format to three other ASCII formats commonly used for
such data.The file calif.tap contains data about earthquakes in
California with magnitudes > 5.0 since 1980. The data were initially
distributed by NGDC on tape, hence the .tap extension. The data
format is described in eqtape.fmt:
Here is the eqtape.fmt file:
/ This is the format description file for the NGDC .tap format, / which is used for data distributed on floppy disks or tapes. ASCII_data ".tap format" source_code 1 3 char 0 century 4 6 short 0 year 7 8 short 0 month 9 10 short 0 day 11 12 short 0 hour 13 14 short 0 minute 15 16 short 0 second 17 19 short 1 latitude_abs 20 24 long 3 latitude_ns 25 25 char 0 longitude_abs 26 31 long 3 longitude_ew 32 32 char 0 depth 33 35 short 0 magnitude_mb 36 38 short 2 MB 39 40 constant 0 isoseismal 41 43 char 0 intensity 44 44 char 0 / The NGDC record check format includes / six flags in characters 45 to 50. These / can be treated as one variable to allow / multiple flags to be set in a single pass, / or each can be set by itself. ngdc_flags 45 50 char 0 diastrophic 45 45 char 0 tsunami 46 46 char 0 seiche 47 47 char 0 volcanism 48 48 char 0 non_tectonic 49 49 char 0 infrasonic 50 50 char 0 fe_region 51 53 short 0 magnitude_ms 54 55 short 1 MS 56 57 char 0 z_h 58 58 char 0 cultural 59 59 char 0 other 60 60 char 0 magnitude_other 61 63 short 2 other_authority 64 66 char 0 ide 67 67 char 0 depth_control 68 68 char 0 number_stations_qual 69 71 char 0 time_authority 72 72 char 0 magnitude_local 73 75 short 2 local_scale 76 77 char 0 local_authority 78 80 char 0
Three other formats used for California earthquake data are
hypoellipse, hypoinverse, and hypo71. Subsets of these formats are
described in the format description file hypo.fmt. The format
descriptions include the parameters required by the AcroSpin program
that is distributed as part of the IASPEI Software Library (Volume 2).
AcroSpin shows 3D views of earthquake point data.
Here is the hypo.fmt file:
/ This format description file describes subsets of the / hypoellipse, hypoinverse, and hypo71 formats. ASCII_data "hypoellipse format" year 1 2 uchar 0 month 3 4 uchar 0 day 5 6 uchar 0 hour 7 8 uchar 0 minute 9 10 uchar 0 second 11 14 ushort 2 latitude_deg_abs 15 16 uchar 0 latitude_ns 17 17 char 0 latitude_min 18 21 ushort 2 longitude_deg_abs 22 24 uchar 0 longitude_ew 25 25 char 0 longitude_min 26 29 ushort 2 depth 30 34 short 2 magnitude_local 35 36 uchar 1 ASCII_data "hypoinverse format" year 1 2 uchar 0 month 3 4 uchar 0 day 5 6 uchar 0 hour 7 8 uchar 0 minute 9 10 uchar 0 second 11 14 ushort 2 latitude_deg_abs 15 16 uchar 0 latitude_ns 17 17 char 0 latitude_min 18 21 ushort 2 longitude_deg_abs 22 24 uchar 0 longitude_ew 25 25 char 0 longitude_min 26 29 ushort 2 depth 30 34 short 2 magnitude_local 35 36 uchar 1 number_of_times 37 39 short 0 maximum_azimuthal_gap 40 42 short 0 nearest_station 43 45 short 1 rms_travel_time_residual 46 49 short 2 ASCII_data "hypo71 format" year 1 2 uchar 0 month 3 4 uchar 0 day 5 6 uchar 0 hour 8 9 uchar 0 minute 10 11 uchar 0 second 12 17 float 2 latitude_deg_abs 18 20 uchar 0 latitude_ns 21 21 char 0 latitude_min 22 26 float 2 longitude_deg_abs 27 30 uchar 0 longitude_ew 31 31 char 0 longitude_min 32 36 float 2 depth 37 43 float 2 magnitude_local 44 50 float 2 number_of_times 51 53 short 0 maximum_azimuthal_gap 54 57 float 0 nearest_station 58 62 short 1 rms_travel_time_residual 63 67 float 2 error_horizontal 68 72 float 1 error_vertical 73 77 float 1 s_waves_used 79 79 char 0
The parameters from the California earthquake data in the NGDC format needed for use with the AcroSpin program can be extracted and converted using the following commands:
newform calif.tap -if eqtape.fmt -of hypo.fmt
-oft "hypoellipse format" -o calif.he
newform calif.tap -if eqtape.fmt -of hypo.fmt
-oft "hypoinverse format" -o calif.hi
newform calif.tap -if eqtape.fmt -of hypo.fmt
-oft "hypo71 format" -o calif.h71
If you develop an application that accesses seismicity data in a particular ASCII format, you need only to write an appropriate format description file in order to convert NGDC data into the format used by the application. This lets you make use of the data that NGDC provides in a format that works for you.