Hi Chris (& everyone else),

Where can one get more information about the 'Roberts Amplifyer'? 

Kareem



-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of ChrisAtUpw@.......
Sent: Thursday, March 30, 2006 6:58 PM
To: psn-l@..............
Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake

In a message dated 31/03/2006, jonfr500@......... writes:

	Is it impossible for L15B 4.5Hz geophone to detect teleseismic
	earthquakes or just improbable. 

Hi Jon,
 
    The sensitivity is down to ~1/5 at 2 Hz and it falls off increasingly
rapidly below this. At 1 Hz it is ~1/20. So what you can see depends on the
P wave frequency and on the magnitude of the quake. I would say that it may
be 'difficult'. 
    It is possible to use a 'Roberts type' frequency compensating amplifier
to boost the output of a 4.5 Hz geophone fairly level down to ~0.5 Hz. This
enables you to use these geophones fairly well for teleseismic quakes. 
 
    Regards,
 
    Chris Chapman

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