[GRASS-user] Re: How to draw the earthquake-magtintude map...

Dear all,

I wish to express my gratitude to your some advices.

I understood the command that drew in circle.
Also, I understood the magnitude was not simple.

It explains the process...:

(1)
d.vect.thematic map=quake column=mag type=point themetype=graduated_points ico
n=basic/circle

...It succeeded.

(2)
d.vect map=quake size_column=mag icon=basic/circle
...error message "Sorry, <size_column> is not a valid parameter"

(3)
d.vect map=quake size=mag icon=basic/circle
...It succeeded. but very small symbolsize...

(4)
d.vect map=quake size=10^(11+1.5*mag) icon=basic/circle
...error message "token (' syntax error..."...
Why ?

(5)
d.vect map=quake size=10^mag icon=basic/circle
...It succeeded.

----
Yasuo shimada ( Japan weather association )

----- Original Message -----

Date: Wed, 15 Jun 2011 16:46:28 +0900 (JST)
From: sgw00412@nifty.com
To: grass-user@lists.osgeo.org
Subject: How to draw the earthquake-magtintude map...

Dear grass users

I'm from Japan and begginer user of grass GIS.

I tried to draw earthquake map of tohoku Japan.

First, I summarized of some earthquake data, for example lat, lon, depth and

m

agnitude.

---------------------------------
lon lat depth Magnitude
---------------------------------
139.9, 37.7, 10, 3.1
141.0, 35.8, 10, 2.6
142.7, 40.8, 20, 4.4
...
---------------------------------

Second, this text data was imported to grass data by using v.in.ascii, as fol

l

ows;

cat data.txt | v.in.ascii fs=',' cat=0 x=1 y=2 out=quake columns='x double pr

e

cision, y double precision, depth integer, mag double precision'

So, I typed to 'v.vect quake'
These points where the earthquake were displayed by cross (x) .

Next, I tried to display new map as circle size of earthquake-magnitude.

v.vect quake size=magnitude

However, unsuccessful....What should I do?

Yasuo shimada ( Japan weathere association )

Yasuo shimada wrote:

I wish to express my gratitude to your some advices.

I understood the command that drew in circle.
Also, I understood the magnitude was not simple.

It explains the process...:

(1)
d.vect.thematic map=quake column=mag type=point
  themetype=graduated_points icon=basic/circle

...It succeeded.

(2)
d.vect map=quake size_column=mag icon=basic/circle
...error message "Sorry, <size_column> is not a valid
parameter"

ah, what version of GRASS are you using? that option is new for
GRASS 6.4.1. (also the rotation column option)

(3)
d.vect map=quake size=mag icon=basic/circle
...It succeeded. but very small symbolsize...

size= should only accept a number, the default size= is 5.0,
which is quite small. For some reason the parser doesn't
complain that you gave it a string.

(4)
d.vect map=quake size=10^(11+1.5*mag) icon=basic/circle
...error message "token (' syntax error..."...
Why ?

size= is not that smart (yet), but it's a rather good idea!
it just takes a single number.
I am not sure if the "token" error comes from your terminal
shell (needs quoting) or from GRASS (doesn't support that), but
either way, it won't work.

(5)
d.vect map=quake size=10^mag icon=basic/circle
...It succeeded.

I suspect that atof() just scanned as far as the "10", and
then used that as a static size.

try upgrading to 6.4.1, and the size_column= option should
start to work. (n.b. adding this option was actually inspired by
the desire to vary symbol size for earthquake plots)

also you will find in GRASS 6.4.1 the new extra/ring symbol,
which is similar to basic/circle with fill_color=none, but
allows the dynamic color setting to colorize the border line,
not the fill area. (so the fill area does not mask smaller quakes
at close epicenters)

see here for method of adding a new column, containing a measure
of un-logged energy, which can then be used for the d.vect
size_column:

https://trac.osgeo.org/grass/browser/grass-promo/tutorials/batch_processing/earthquakes/do_quakes_latlon.sh#L67

Hamish