Started: 2008-01-22 20:15:52
Last activity: 2008-01-31 17:44:00
Topics:
Katie Stofer
2008-01-22 20:15:52
From the Maryland Science Center ...

I have a more general question about quakes that I hope one of the
experts can help me with. We have been using a machine to simulate
earthquakes that ostensibly varies magnitude - Pitsco's Epicenter
Earthquake Simulator. They no longer make this and now sell instead the
EQ Tremor Table
http://catalog.pitsco.com/store/detail.aspx?KeyWords=engineering&by=20&ID=4229&c=0&t=0&l=0,
which, instead of magnitude, varies cycles per second (frequency), from
0-30, "in the range of P waves." So, is there a relationship between
frequency and magnitude (the latter being the one that school groups
visiting the science center are more familiar with)? Was our original
machine really varying magnitude (being built, as far as I can tell, on
some sort of belt sander with a variable voltage control), or just
frequency as far as anyone can tell?

Any ideas/insight are appreciated before I rewrite our entire program
due to a broken simulator!

Thanks,
Katie Stofer

--
--
Kathryn Stofer
Maryland Science Center
601 Light Street
Baltimore, Maryland 21230
410/545-5976
410/545-5974 fax
BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!

• Michael Hubenthal
2008-01-28 22:59:58
Hi Katie,

I haven't seen a reply to your post yet so I will take a crack at a
response.

In short, my guess is that the previous machine took some artistic
liberties and it sounds like they weren't discussed in the manuals.
There is a relationship between Period (1/frequency) and Magnitude
however there are other factors involved. For example the equation
to determine magnitude using body waves is Mb = log(A/T) + s. Where
(A) is the amplitude of the P-wave train, the first arriving body
wave, (T) is the period of the displacement, and (s) is a correction
term. Larry Braile suggest that for the AS-1 program s=0.01*D + 5.9
where D is distance to the event.

The problem with describing the changes in shaking only in terms of
magnitude only is that it doesn't account for other factors such as
the distance to the epicenter, regional geology etc. However, the
folks at Pitsco probably just said, lets assume that all of these
other factors are held as constants and put a magnitude sticker on
there (or they may not have even thought about it that much).

I guess in thinking about your activity, what is the content that you
want to convey to them?

Best Wishes
Michael

On Jan 22, 2008, at 12:15 PM, Katie Stofer wrote:

From the Maryland Science Center ...

I have a more general question about quakes that I hope one of the
experts can help me with. We have been using a machine to simulate
earthquakes that ostensibly varies magnitude - Pitsco's Epicenter
Earthquake Simulator. They no longer make this and now sell instead
the EQ Tremor Table, which, instead of magnitude, varies cycles per
second (frequency), from 0-30, "in the range of P waves." So, is
there a relationship between frequency and magnitude (the latter
being the one that school groups visiting the science center are
more familiar with)? Was our original machine really varying
magnitude (being built, as far as I can tell, on some sort of belt
sander with a variable voltage control), or just frequency as far
as anyone can tell?

Any ideas/insight are appreciated before I rewrite our entire
program due to a broken simulator!

Thanks,
Katie Stofer
-- -- Kathryn Stofer TerraLink Exhibit Manager Maryland Science
Center 601 Light Street Baltimore, Maryland 21230 410/545-5976
410/545-5974 fax BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!
_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

---------------------------------
Michael Hubenthal
Education Specialist
IRIS Consortium
607-777-4612
www.IRIS.edu
hubenth<at>iris.edu

• Jerry R. Cook
2008-01-28 21:47:23
Hi All,
I have a problem with my display that is driving me nuts. Every time the
display goes to a new line at the end of the hour there is a spike on the
new line. Check it out at this link;
http://www.pcds.org/share/earthquake/

This a real problem if an earthquake happens to span two lines. When I
extract the event all I get is the spike and the seismic waves are about 1mm
high. Any suggestions?
J. Bob

• Alan Jones
2008-01-29 00:57:35
Jerry,

This could be because you don't have the seismometer zeroed out. A constant offset can cause this.

Turn off all filtering and make sure the active trace is right on the blue line. With the filtering turned off, do you still get the spiles?

Are you sure the data shows up as a spike when you extract? It doesn't with me. It's just that each line is filtered separately and there is some start-up problems at the beginning of the line.

I'm copying John Lahr and the IRIS listserv to see if others have ideas.

Let us know if this helps.

Alan

############################
# Alan Jones
## AlanJones<at>stny.rr.com
### http://home.stny.rr.com/alanjones
#### 607-786-5866
##### 3717 Wildwood Drive
###### Endwell, NY 13760
############################
----- Original Message -----
From: Jerry Cook
To: irised<at>iris.washington.edu
Sent: Monday, January 28, 2008 3:47 PM
Subject: [irised] Annoying Spikes

Hi All,
I have a problem with my display that is driving me nuts. Every time the
display goes to a new line at the end of the hour there is a spike on the
new line. Check it out at this link;
http://www.pcds.org/share/earthquake/

This a real problem if an earthquake happens to span two lines. When I
extract the event all I get is the spike and the seismic waves are about 1mm
high. Any suggestions?
J. Bob

_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

• Jerry Cook
2008-01-29 03:52:22
Dear Dr. Jones,
You rock! When I turned off all filtering the active trace was 21 hours off. Now that I have it centered on the correct hour the spikes are gone. I have no Idea how the trace got so far off. I will add this little gem of knowledge to my list of trouble shooting fixes.
Cheers,
J. Bob

________________________________

From: Alan Jones [AlanJones<at>stny.rr.com]
Sent: Mon 1/28/2008 2:57 PM
To: Jerry Cook
Cc: John Lahr; IRISED
Subject: Re: [irised] Annoying Spikes

Jerry,

This could be because you don't have the seismometer zeroed out. A constant offset can cause this.

Turn off all filtering and make sure the active trace is right on the blue line. With the filtering turned off, do you still get the spiles?

Are you sure the data shows up as a spike when you extract? It doesn't with me. It's just that each line is filtered separately and there is some start-up problems at the beginning of the line.

I'm copying John Lahr and the IRIS listserv to see if others have ideas.

Let us know if this helps.

Alan

############################
# Alan Jones
## AlanJones<at>stny.rr.com
### http://home.stny.rr.com/alanjones
#### 607-786-5866
##### 3717 Wildwood Drive
###### Endwell, NY 13760
############################

----- Original Message -----
From: Jerry Cook <jerry.cook<at>pcds.org>
To: irised<at>iris.washington.edu
Sent: Monday, January 28, 2008 3:47 PM
Subject: [irised] Annoying Spikes

Hi All,
I have a problem with my display that is driving me nuts. Every time the
display goes to a new line at the end of the hour there is a spike on the
new line. Check it out at this link;
http://www.pcds.org/share/earthquake/

This a real problem if an earthquake happens to span two lines. When I
extract the event all I get is the spike and the seismic waves are about 1mm
high. Any suggestions?
J. Bob

_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

• John Taber
2008-01-29 23:46:27
Katie,

As Michael says, the key question is what concepts were you
presenting with your old system? Did the amplitude of the shaking
appear to vary? If you were primarily talking about building damage
then varying the frequency may be enough, as building damage depends
more on the local acceleration of the ground than it does on the
magnitude of the earthquake.

If you have someone one on your staff who can build you a new shake
table you might consider John Lahr's version or any of the other ones
he lists on his web page: http://jclahr.com/science/earth_science/
shake/. John may want to comment, but it looks like most of the low
cost, motor-driven shake tables vary the frequency more so than the
amplitude.

John

On Jan 28, 2008, at 2:59 PM, Michael Hubenthal wrote:

Hi Katie,

I haven't seen a reply to your post yet so I will take a crack at a
response.

In short, my guess is that the previous machine took some artistic
liberties and it sounds like they weren't discussed in the
manuals. There is a relationship between Period (1/frequency) and
Magnitude however there are other factors involved. For example
the equation to determine magnitude using body waves is Mb = log(A/
T) + s. Where (A) is the amplitude of the P-wave train, the first
arriving body wave, (T) is the period of the displacement, and (s)
is a correction term. Larry Braile suggest that for the AS-1
program s=0.01*D + 5.9 where D is distance to the event.

The problem with describing the changes in shaking only in terms of
magnitude only is that it doesn't account for other factors such as
the distance to the epicenter, regional geology etc. However, the
folks at Pitsco probably just said, lets assume that all of these
other factors are held as constants and put a magnitude sticker on
there (or they may not have even thought about it that much).

I guess in thinking about your activity, what is the content that
you want to convey to them?

Best Wishes
Michael

On Jan 22, 2008, at 12:15 PM, Katie Stofer wrote:

From the Maryland Science Center ...

I have a more general question about quakes that I hope one of the
experts can help me with. We have been using a machine to simulate
earthquakes that ostensibly varies magnitude - Pitsco's Epicenter
Earthquake Simulator. They no longer make this and now sell
cycles per second (frequency), from 0-30, "in the range of P
waves." So, is there a relationship between frequency and
magnitude (the latter being the one that school groups visiting
the science center are more familiar with)? Was our original
machine really varying magnitude (being built, as far as I can
tell, on some sort of belt sander with a variable voltage
control), or just frequency as far as anyone can tell?

Any ideas/insight are appreciated before I rewrite our entire
program due to a broken simulator!

Thanks,
Katie Stofer
-- -- Kathryn Stofer TerraLink Exhibit Manager Maryland Science
Center 601 Light Street Baltimore, Maryland 21230 410/545-5976
410/545-5974 fax BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!
_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

---------------------------------
Michael Hubenthal
Education Specialist
IRIS Consortium
607-777-4612
www.IRIS.edu
hubenth<at>iris.edu

• Katie Stofer
2008-01-30 00:56:33
Thanks Michael and John -

Yes, I think the frequency was probably what changed. The amplitude
varied slightly, too, as the shaking got faster, but I think it wasn't
the primary variable.

The program is focused more as a general overview of earthquakes - where
they occur, when, what magnitude is (just enough to talk about how we
measure quakes against one another). The building is supposed to be a
fun, hands-on wrap-up. Many classes treat this either as a good
summary/reminder of their earlier curriculum or as an intro to an
upcoming curriculum.
I guess I was assuming (and implying, though not explicitly stating to
the students) that the "buildings" were at the epicenter of the
earthquake, and the quake was in some quake-prone area such as So.
California. At this point in the program, the "magnitude" was really
meant to convey stronger shaking to wrap up what I'd reviewed/introduced
about quakes. I don't go into too much about waves, as I'm generally
dealing with younger students. I'm only wedded to the current activity
as it is already created, but the table is failing, and with the new
version (frequency variable), I was confused about the frequency part
and its relationship to magnitude.

For simplicity's sake, were I to get the new table, am I correct in
saying that as frequency increases, magnitude increases (all else being
constant), so that as we turn up the frequency, we're approximating an
increase in magnitude? (as I don't talk about frequency, period, etc. -
just magnitude).

Thanks for all your help. Hope this isn't too off-topic!
-Katie

John Taber wrote:
Katie,

As Michael says, the key question is what concepts were you presenting
with your old system? Did the amplitude of the shaking appear to
vary? If you were primarily talking about building damage then
varying the frequency may be enough, as building damage depends more
on the local acceleration of the ground than it does on the magnitude
of the earthquake.

If you have someone one on your staff who can build you a new shake
table you might consider John Lahr's version or any of the other ones
he lists on his web page:
http://jclahr.com/science/earth_science/shake/. John may want to
comment, but it looks like most of the low cost, motor-driven shake
tables vary the frequency more so than the amplitude.

John

On Jan 28, 2008, at 2:59 PM, Michael Hubenthal wrote:

Hi Katie,

I haven't seen a reply to your post yet so I will take a crack at a
response.

In short, my guess is that the previous machine took some artistic
liberties and it sounds like they weren't discussed in the manuals.
There is a relationship between Period (1/frequency) and Magnitude
however there are other factors involved. For example the equation
to determine magnitude using body waves is Mb = log(A/T) + s. Where
(A) is the amplitude of the P-wave train, the first arriving body
wave, (T) is the period of the displacement, and (s) is a correction
term. Larry Braile suggest that for the AS-1 program s=0.01*D + 5.9
where D is distance to the event.

The problem with describing the changes in shaking only in terms of
magnitude only is that it doesn't account for other factors such as
the distance to the epicenter, regional geology etc. However, the
folks at Pitsco probably just said, lets assume that all of these
other factors are held as constants and put a magnitude sticker on
there (or they may not have even thought about it that much).

I guess in thinking about your activity, what is the content that you
want to convey to them?

Best Wishes
Michael

On Jan 22, 2008, at 12:15 PM, Katie Stofer wrote:

From the Maryland Science Center ...

I have a more general question about quakes that I hope one of the
experts can help me with. We have been using a machine to simulate
earthquakes that ostensibly varies magnitude - Pitsco's Epicenter
Earthquake Simulator. They no longer make this and now sell instead
the EQ Tremor Table, which, instead of magnitude, varies cycles per
second (frequency), from 0-30, "in the range of P waves." So, is
there a relationship between frequency and magnitude (the latter
being the one that school groups visiting the science center are
more familiar with)? Was our original machine really varying
magnitude (being built, as far as I can tell, on some sort of belt
sander with a variable voltage control), or just frequency as far as
anyone can tell?

Any ideas/insight are appreciated before I rewrite our entire
program due to a broken simulator!

Thanks,
Katie Stofer
-- -- Kathryn Stofer TerraLink Exhibit Manager Maryland Science
Center 601 Light Street Baltimore, Maryland 21230 410/545-5976
410/545-5974 fax BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!
_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

---------------------------------
Michael Hubenthal
Education Specialist
IRIS Consortium
607-777-4612
www.IRIS.edu
hubenth<at>iris.edu

--
--
Kathryn Stofer
Maryland Science Center
601 Light Street
Baltimore, Maryland 21230
410/545-5976
410/545-5974 fax
BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!

• John Taber
2008-01-31 17:44:00
Katie,

For the purposes of a simple demonstration for younger students, and
if you aren't using it to demonstrate the effects of frequency (ie
the varying resonance of buildings of different heights) and don't
talk about increasing the frequency, then I guess you could say the
magnitude is increasing. If a teacher asks a question, you could
say that what you really are doing is increasing the acceleration and
thus the likelihood of damaging the building. We do in our building
design and destruction exercise where we place an accelerometer on
the structure.

John

On Jan 29, 2008, at 4:56 PM, Katie Stofer wrote:

Thanks Michael and John -

Yes, I think the frequency was probably what changed. The amplitude
varied slightly, too, as the shaking got faster, but I think it
wasn't the primary variable.

The program is focused more as a general overview of earthquakes -
where they occur, when, what magnitude is (just enough to talk
about how we measure quakes against one another). The building is
supposed to be a fun, hands-on wrap-up. Many classes treat this
either as a good summary/reminder of their earlier curriculum or as
an intro to an upcoming curriculum.
I guess I was assuming (and implying, though not explicitly stating
to the students) that the "buildings" were at the epicenter of the
earthquake, and the quake was in some quake-prone area such as So.
California. At this point in the program, the "magnitude" was
really meant to convey stronger shaking to wrap up what I'd
waves, as I'm generally dealing with younger students. I'm only
wedded to the current activity as it is already created, but the
table is failing, and with the new version (frequency variable), I
was confused about the frequency part and its relationship to
magnitude.

For simplicity's sake, were I to get the new table, am I correct in
saying that as frequency increases, magnitude increases (all else
being constant), so that as we turn up the frequency, we're
approximating an increase in magnitude? (as I don't talk about
frequency, period, etc. - just magnitude).

Thanks for all your help. Hope this isn't too off-topic!
-Katie

John Taber wrote:
Katie,

As Michael says, the key question is what concepts were you
presenting with your old system? Did the amplitude of the
shaking appear to vary? If you were primarily talking about
building damage then varying the frequency may be enough, as
building damage depends more on the local acceleration of the
ground than it does on the magnitude of the earthquake.

If you have someone one on your staff who can build you a new
shake table you might consider John Lahr's version or any of the
other ones he lists on his web page: http://jclahr.com/science/
earth_science/shake/. John may want to comment, but it looks like
most of the low cost, motor-driven shake tables vary the frequency
more so than the amplitude.

John

On Jan 28, 2008, at 2:59 PM, Michael Hubenthal wrote:

Hi Katie,

I haven't seen a reply to your post yet so I will take a crack at
a response.

In short, my guess is that the previous machine took some
artistic liberties and it sounds like they weren't discussed in
the manuals. There is a relationship between Period (1/
frequency) and Magnitude however there are other factors
involved. For example the equation to determine magnitude using
body waves is Mb = log(A/T) + s. Where (A) is the amplitude of
the P-wave train, the first arriving body wave, (T) is the period
of the displacement, and (s) is a correction term. Larry Braile
suggest that for the AS-1 program s=0.01*D + 5.9 where D is
distance to the event.

The problem with describing the changes in shaking only in terms
of magnitude only is that it doesn't account for other factors
such as the distance to the epicenter, regional geology etc.
However, the folks at Pitsco probably just said, lets assume that
all of these other factors are held as constants and put a
magnitude sticker on there (or they may not have even thought

I guess in thinking about your activity, what is the content that
you want to convey to them?

Best Wishes
Michael

On Jan 22, 2008, at 12:15 PM, Katie Stofer wrote:

From the Maryland Science Center ...

I have a more general question about quakes that I hope one of
the experts can help me with. We have been using a machine to
simulate earthquakes that ostensibly varies magnitude - Pitsco's
Epicenter Earthquake Simulator. They no longer make this and now
varies cycles per second (frequency), from 0-30, "in the range
of P waves." So, is there a relationship between frequency and
magnitude (the latter being the one that school groups visiting
the science center are more familiar with)? Was our original
machine really varying magnitude (being built, as far as I can
tell, on some sort of belt sander with a variable voltage
control), or just frequency as far as anyone can tell?

Any ideas/insight are appreciated before I rewrite our entire
program due to a broken simulator!

Thanks,
Katie Stofer
-- -- Kathryn Stofer TerraLink Exhibit Manager Maryland Science
Center 601 Light Street Baltimore, Maryland 21230 410/545-5976
410/545-5974 fax BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!
_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

---------------------------------
Michael Hubenthal
Education Specialist
IRIS Consortium
607-777-4612
www.IRIS.edu
hubenth<at>iris.edu

--
--
Kathryn Stofer
Maryland Science Center
601 Light Street
Baltimore, Maryland 21230
410/545-5976
410/545-5974 fax
BODYWORLDS - Coming to MSC Feb. 2 - Sept. 1, 2008!

_______________________________________________
irised mailing list
irised<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/irised

00:19:46 v.22510d55