Atmospheric Pressure Change Associated with the 2003 Tokachi-Oki Earthquake

Shingo Watada, Takashi Kunugi, Keinji Hiarata, Hiroko Sugioka, Kiwamu Nishida, Shoji Sekiguchi, Jun Oikawa, Yoshinobu Tsuji, Hiroo Kanamori

microbarogram 2003/09/26

２４ hour

1000sec

JIZODO STS1 vault

Software configuration

Microbarograph recording and telemetry systems

Hardware configuration

GPS antenna

Sensor

Control PC

On-line board PC based systemSGN (Yamanashi, Japan)

Air batteryPortable sensor

Board PC

Microbarograph sensor

Off-line recording system

Ground verticalvelocity

Filtered atmosphericpressure

3.2km/sec

)exp( tzmxk

atmosphere

Ground

w

)exp( tzmxk

atmosphere

Ground

w

cfw

fp )(

)(

for homogeneous fluid

Observational transfer functionwc

p

Mechanical sensitivty check by shake table

cwgh

cwgh

response acoustic nt displaceme static

tableshakeFor

response acoustic nt displaceme static

ground at the wavesseismicFor

Theoretical transfer functionof long-period atmospheric waves.

)exp( tzmxk

atmosphere

Ground

w

),()(

)(kfZ

fcw

fp

for homogeneous fluid

2

/1

1

k

cwc

p

ss

High frequency asymptotefor propagating acoustic waves

Conclustion

The atmospheric pressure change associted with the 2003 Tokachi-Okiearthquake are observed at the co-located site of broadband seismometers.

The origin of atmospheric pressure change is the Rayleigh waves passing atthe site.

The observational transfer functions, both phase and amplitude, are constructedand compared with the theoretical transfer functions and found consistent up to50 sec.