.. index:: ! originater .. include:: ../module_supplements_purpose.rst_ ********** originater ********** |originater_purpose| Synopsis -------- .. include:: ../../common_SYN_OPTs.rst_ **gmt originater** [ *table* ] |-E|\ *rot_file*\|\ *ID1-ID2*\|\ *lon*/*lat*/*angle*\ [**+i**] |-F|\ *hs_file*\ [**+d**] [ |-D|\ *d_km* ] [ |-L|\ [**l**\|\ **t**\|\ **w**\| **L**\|\ **T**\|\ **W**] ] [ |-N|\ *upper_age* ] [ |-Q|\ *r/t* ] [ |-S|\ [*n_hs*] ] [ |-T| ] [ |SYN_OPT-V| ] [ |-W|\ *maxdist* ] [ |-Z| ] [ |SYN_OPT-bi| ] [ |SYN_OPT-di| ] [ |SYN_OPT-e| ] [ |SYN_OPT-h| ] [ |SYN_OPT-i| ] [ |SYN_OPT-q| ] [ |SYN_OPT-s| ] [ |SYN_OPT-:| ] [ |SYN_OPT--| ] |No-spaces| Description ----------- **originater** reads (longitude, latitude, height, radius, crustal_age) records from *table* [or standard input] and uses the given Absolute Plate Motion (APM) stage or total reconstruction rotation file and the list of hotspot locations to determine the most likely origin (hotspot) for each seamount. It does so by calculating flowlines back in time and determining the closest approach to all hotspots [*Wessel*, 1999]. The output consists of the input records with four additional fields added for each of the *n_hs* closest hotspots. The four fields are the hotspot id (e.g., HWI), the stage id of the flowline segment that came closest, the pseudo-age of the seamount, and the closest distance to the hotspot (in km). See option **-:** on how to read (latitude, longitude,height, radius, crustal_age) files. Required Arguments ------------------ .. |Add_intables| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_intables.rst_ .. include:: explain_rots.rst_ .. _-F: **-F**\ *hs_file*\ [**+d**] Give file with hotspot locations. This file must contain one record for each hotspot to be considered; each record must be of the following format: lon lat hs_abbrev hs_id r t_off t_on create fit plot name E.g., for Hawaii this may look like 205 20 HWI 1 25 0 90 Y Y Y Hawaii Most applications only need the first 4 columns which thus represents the minimal hotspot information record type. The abbreviation may be maximum 3 characters long. The id must be an integer from 1-32. The positional uncertainty of the hotspot is given by r (in km). The t_off and t_on variables are used to indicate the active time-span of the hotspot. The create, fit, and plot indicators are either Y or N and are used by some programs to indicate if the hotspot is included in the ID-grids used to determine rotations, if the hotspot chain will be used to determine rotations, and if the hotspot should be included in various plots. The name is a 32-character maximum text string with the full hotspot name. Blank lines and records whose first column contains # will be ignored. Append **+d** if we should look for hotspot drift table whose name must be *hs_abbrev*\ \_drift.txt. Such files may be located in the current directory, the same directory as *hs_file*, or in the directories pointed to by GMT_DATADIR. If found then we interpolate to get hotspot location as a function of time [fixed]. Optional Arguments ------------------ .. _-D: **-D**\ *d_km* Sets the flowline sampling interval in km. [Default is 5]. .. _-L: **-L**\ [**l**\|\ **t**\|\ **w**\| **L**\|\ **T**\|\ **W**] Output closest approach for nearest hotspot only (ignores |-S|). Choose **-Lt** for (*time*, *dist*, *z*) [Default], **-Lw** for (*omega*, *dist*, *z*), and **-Ll** for (*lon, lat, time, dist, z*). Normally, *dist* is in km; use upper case modifiers **TWL** to get *dist* in spherical degrees. .. _-N: **-N**\ *upper_age* Set the maximum age to extend the oldest stage back in time [no extension]. .. _-Q: **-Q**\ *r/t* Input files only has (*x*,\ *y*,\ *z*); specify constant values for *r*,\ *t* that will be implied for each record. .. _-S: **-S**\ [*n_hs*] Set the number of closest hotspots to report [Default is 1]. .. _-T: **-T** Truncate seamount ages exceeding the upper age set with |-N| [no truncation]. .. |Add_-V| replace:: |Add_-V_links| .. include:: /explain_-V.rst_ :start-after: **Syntax** :end-before: **Description** .. _-W: **-W**\ *maxdist* Only report those seamounts whose flowlines came within *maxdist* to any hotspot [Default reports all seamounts]. .. _-Z: **-Z** Use the hotspot ID number rather than the name tag in output records. .. |Add_-bi| replace:: [Default is 5 input columns]. .. include:: ../../explain_-bi.rst_ .. |Add_-di| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-di.rst_ .. |Add_-e| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-e.rst_ .. |Add_-h| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-h.rst_ .. include:: ../../explain_-icols.rst_ .. include:: ../../explain_-q.rst_ .. include:: ../../explain_-s.rst_ .. include:: ../../explain_colon.rst_ .. include:: ../../explain_help.rst_ .. include:: explain_geodetic.rst_ Examples -------- To find the likely (hotspot) origins of the seamounts represented by the (*x, y, z, r, tc*) points in the file seamounts.txt, using the DC85.txt Euler poles and the pac_hs.txt list of possible hotspots, and report the 2 most likely hotspot candidates for each seamount, run :: gmt originater seamounts.txt -S2 -EDC85.txt -Fpac_hs.txt > origins.txt To determine the predicted age of a seamount, distances to the closest hotspot, and echo the observed age given its location, observed age, and a rotation model, try :: echo "1.55 -8.43 52.3" | gmt originater -FONeill_2005_hotspots.txt \ -EOMS2005_APM_fixed.txt -Q1/120 -Lt where 52.3 Ma is observed age. The output is 70 -95.486 52.3. To repeat the same exercise with a moving hotspot model, try :: echo "1.55 -8.43 52.3" | gmt originater -FONeill_2005_hotspots.txt+d \ -EOMS2005_APM_smooth.txt -Q1/120 -Lt Now the output is 80 -213.135 52.3. Negative distances means the closest approach was east of the hotspot. Notes ----- GMT distributes the EarthByte rotation model Global_EarthByte_230-0Ma_GK07_AREPS.rot. To use an alternate rotation file, create an environmental parameters named **GPLATES_ROTATIONS** that points to an alternate rotation file. See Also -------- :doc:`gmt `, :doc:`grdrotater`, :doc:`grdspotter`, :doc:`project `, :doc:`mapproject `, :doc:`backtracker`, :doc:`gmtpmodeler`, :doc:`grdpmodeler`, :doc:`grdrotater`, :doc:`hotspotter` References ---------- Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80 (29), p. 319.