From crotwell at seis.sc.edu  Mon Nov 16 13:18:13 2009
From: crotwell at seis.sc.edu (Philip Crotwell)
Date: Mon, 16 Nov 2009 16:18:13 -0500
Subject: [data-issues] repeating stations in db
Message-ID: <1e63606c0911161318u4e535f9fg1b234ce76a025102@mail.gmail.com>

Hi all

I have a question about the "station" entries in the database. For
example, there are 6 IU.TIXI stations from seismoquery:

NETWORK 	STATION 	STARTTIME 	ENDTIME 	LAT 	LON 	ELEVATION 	SITE
IU 	TIXI 	1995-08-15 00:00:00 	1997-02-10 08:20:00 	+71.634100
	+128.866700 	40 	Tiksi, Russia
IU 	TIXI 	1997-02-10 08:20:00 	1997-10-01 00:00:00 	+71.634100
	+128.866700 	40 	Tiksi, Russia
IU 	TIXI 	1997-10-01 00:00:00 	1997-10-18 00:00:00 	+71.634100
	+128.866700 	40 	Tiksi, Russia
IU 	TIXI 	1997-10-18 00:00:00 	1997-11-14 00:00:00 	+71.634100
	+128.866700 	40 	Tiksi, Russia
IU 	TIXI 	1997-11-14 00:00:00 	1997-12-15 13:00:00 	+71.634100
	+128.866700 	40 	Tiksi, Russia
IU 	TIXI 	1997-12-15 13:00:00 	2599-12-31 23:59:59 	+71.634100
	+128.866700 	40 	Tiksi, Russia

I know that here are many changes that can happen to cause channels to
close and new ones to start at a station, but is there a rule on when
a new "station" should be created? It seems weird to me to have so
many copies, especially when as far as I can tell nothing about the
station proper has changed (ie lat, lon, etc), just the effective
times. And all but 11 IU stations are duplicated at least once.

In contrast, only 3 II stations are duplicated.

Is this intentional, or is it a mistaken creation due to bad dataless
being submitted, perhaps a new station being created every time the
channels change configuration? I suppose it is not a big deal, but it
does seem confusing.

thanks,
Philip