[SAC-HELP] sac file extraction

[Shuo Ma]

I was trying to extract the SAC file (*.tgz) IRIS sent me and install 
SAC on my MacBook Pro.  However, two ways to extract files they suggest 
in the email didn't work.  Here are the error messages:

hr-shuoma-1158617981:/Applications shuoma$ tar zxvf 
05Mar01.sac.bin.darwin.tgz

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error exit delayed from previous errors
hr-shuoma-1158617981:/Applications shuoma$ gzip -d -c 
05Mar01.sac.bin.darwin.tgz | tar -xf -

gzip: 05Mar01.sac.bin.darwin.tgz: not in gzip format
hr-shuoma-1158617981:/Applications shuoma$

Does anyone know what to do?  Is the file corrupted?

Thanks,
Shuo