ASOBOI97: Aso Seismic Observation with BrOadband Instruments in 1997
Yamamoto, M., H. Kawakatsu, S. Kaneshima,
T. Iidaka, J. Oikawa, S. Watada, Y. Morita,
T. Mori, T. Tsutsui, Y. Sudo,
M. Yoshikawa, T. Hashimoto, M. Nakabo
Bull. Earthquake Res. Inst., in press, 2000
Abstract
In August, 1997, we deployed totally 24 broadband three-component velocity
seismometers temporarily around Aso volcano in Kyushu, Japan.
Most of these stations were located within 1 km around
the 1st crater of Naka-dake
and provided a good azimuthal coverage to constrain the geometry of the
source region of the long-period (15\,s) tremors (LPTs).
The spatial pattern of the observed LPTs amplitude reveals
that the source of LPTs consists of an
isotropic expansion (contraction) and an inflation (deflation)
of an inclined tensile crack almost parallel to the chain of
the craters of the Naka-dake (Yamamoto et al., 1999).
This report, which is based on Chapter 1 of the
MS thesis of Yamamoto (1999), summarizes the detail of the observation
as well as some of the characteristics of the observed data from
ASOBOI97 expedition.