PSN-L Email List Message

Subject: RE: Natural Microseismic Noise
From: "Bob Hancock" carpediem1@.........
Date: Sun, 17 Sep 2006 07:28:36 -0700

Chris & Geoff - 

I also picked up the microseisms yesterday, and they had a rhythmic or
cyclic appearance, with a time of about 1 minute between peaks in amplitude.
The frequency of the oscillations was between, 0.19 hz, and 0.24 hz.

I correlated yesterdays' microseisms with the winds in the area of the
Mogollon Rim.  Flagstaff, AZ airport (KFLG), about 24 km north of the rim
had winds up to 20 knots at the time, but that is not uncommon for that
area.  The area is flat terrain, populated with many high pine trees with a
dormant volcano on the north side of town.  You can see the microseism
locally, but they do not transmit for great distances.

I also correlated the winds at Winslow, AZ airport (KINW) further east, and
about 80 km from the rim.  This is high desert, flat terrain basically void
of trees and most everything else.  The winds were less.  The winds at Mesa,
AZ, (KFFZ), near where Geoff lives were also under 10 knots.

The microseisms were rhythmic, similar to ocean waves I have previously
observed while living in New Jersey on the East Coast of the US.  At the
time of the microseisms, Hurricane Lane was in the Gulf of Baja traveling
northwest.  The hurricane has subsequently moved more over land (Mexico) and
the microseisms have subsided.

One other thought - I have observed significant differences in the signature
of wind noise and wave noise.  The ocean wave noise I have observed has
always been more cyclic or rhythmic where it increases and decreases in
intensity over a period of time.  However, the wind noise I have observed
has always been more local in nature, and gives a more or less constant
increase in background noise without the cyclic/rhythmic increases and

There is a strong possibility these microseisms were related to Hurricane
Lane making landfall below the tip of the Gulf of Baja. 

When east coast hurricanes make land fall, they are easily observable here
in the Arizona desert.

You can check world wide ocean wave activity from this US Navy web site.

You can also track hurricanes and typhoons at this web site.

You can also download a very nice conversion program for all types of
calculations at the following web site.

Bob Hancock
Three Points, AZ

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Geoffrey
Sent: Sunday, September 17, 2006 01:14
To: psn-l@..............
Subject: Re: Natural Microseismic Noise

Thanks for your response Chris.


Public Seismic Network Mailing List (PSN-L)


Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]