[data-issues] mag 9.5 bogus event in db

Philip Crotwell crotwell at seis.sc.edu
Fri Apr 10 10:52:05 PDT 2009

Hi all

Just FYI as I assume any updates flow automatically via secret
messages carried in IRIS's top secret diplomatic pouch.


---------- Forwarded message ----------
From: James <james at isc.ac.uk>
Date: Thu, Apr 9, 2009 at 11:06 AM
Subject: Re: [Fwd: bad large magnitudes in catalog]
To: crotwell at seis.sc.edu


Thank you for finding this and letting us know. I have checked with our
seismologists and deleted this magnitude. Normally extreme magnitudes
would be spotted and removed during the editing process but somehow this
one escaped. I have forwarded your email to our director and he should
be able to answer with more detail if needed. I am going to review out
data to check for other rogue magnitudes.

Best wishes


> Hi
> There are a couple of events in the ISC catalog with very large
> magnitudes that are very likely not real. This came up because REV,
> our education and outreach earthquake viewer (http://rev.seis.sc.edu),
> uses the ISC catalog for older events and it picked up on at least one
> of these (Event  9196527 Philippine Islands region, MS 9.5). The
> result is that the largest earthquake in REV is not really an
> earthquake. I have manually deleted this event, and so this particular
> event is no longer an issue for REV, but I am wondering if this type
> of thing could happen in the future.
> I presume that most of these are reported to you by other
> organizations and so you are simply recording what you were given.
> However, it seem to me that given the public's interest in big
> earthquakes and in particular "what is the biggest earthquake ever"
> that particular attention should be paid to make sure that very large
> but incorrect magnitudes do not get into the final catalog. Do you
> have any system to filter out or flag for further review an magnitude
> estimate that is very large, say bigger than 8 or 9?
> Also, I noticed that there are errata for several events listed the
> Methods and Programs section of the ISC site but only for very old
> data. Is there anything similar that lists errata for newer parts of
> the catalog?
> http://www.isc.ac.uk/doc/database/load_ffb.html#ST51
> thanks,
> Philip Crotwell

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