AMBIENT NOISE AND SITE RESPONSE CHARACTERISTICS AT THE BROADBAND
SEISMOGRAPHIC STATIONS OF THE LAMONT COOPERATIVE SEISMOGRAPHIC NETWORK

GOLD, M., Lamont-Doherty Earth Observatory of Columbia University,
Palisades, NY 10964; EATON, T., CUNY- Queens College, Flushing, NY
11367; STERNBERG, R., Franklin & Marshall College, Lancaster, PA 17604;
RUBIN, P., Howe Caverns, Howes Cave, NY 12092; KLOSKO, E.,
SUNY-Westchester Community College, Valhalla, NY 10595; BRENNAN, B.,
SUNY-Geneseo College, Geneseo, NY 14454.

The Lamont Cooperative Seismic Network (LCSN) now consists of 21
broadband seismographic stations in New York, Connecticut, New Jersey,
Pennsylvania, Delaware and Maryland operated by 25 cooperating
partners, with Lamont-Doherty Earth Observatory (LDEO) serving as the
lead institution.  The network and its participants are past its
deployment stage, and are starting to analyze data for education and
scientific research.  We realized that it is imperative to have a good
understanding of the ambient noise characteristics and site response of
each station, in order to correctly utilize the data. Hence, we began
to analyze the data using a software tool, QUACK (QUality Analysis
Control Kit) available on the IRIS-DMC web site for waveform data
archived there with corresponding instrument response in DATALESS SEED
as for all LCSN data. Preliminary analysis of the ambient noise
suggests that the microseism noise spectral peak at PRNY (Ithaca, NY)
is about 0.2 Hz (5 second-period), which is slightly shorter period
than at PAL and HCNY (Howe Caverns, Cobleskill, NY; 7-8 second-period),
probably due to lower microseisms at PRNY, as the site is a farther
distance from the Atlantic Ocean than PAL or HCNY.  The broadband
stations of LCSN are distributed in diverse environments such as a 45 m
deep natural cave (HCNY), middle of the most dynamic city in the world
(CPNY in Manhattan), and relatively quiet mountain sites (NCB, FRNY;
Flat Rock, Altona, NY). For site characteristics, we take horizontal
versus vertical component amplitude spectral ratio of regional signals
to constrain the empirical site response.  We evaluate Rayleigh wave
empirical Green's function by cross-correlation of ambient noise data
for pairs of stations as suggested by Shapiro and Campillo (2004).