We analyzed the IRIS broad-band seismograms for the June 9, 1994, Boli
via earthquake, the largest deep-focus earthquake ever recorded. We in
verted the record sections with a duration of 330 sec which include P,
pP and sP phases, and obtained a dip-slip mechanism: (dip(delta), rak
e(lambda), strike(phi)) = (13-degrees, -4-degrees, 1-degree) or (89-de
grees, -103-degrees, 95-degrees), with a scalar moment of Mo = 2.9 x 1
0(21) Nm (Mw = 8.2). This mechanism is similar to that obtained from l
ong-period (175 to 250 sec) Rayleigh and Love waves: (delta, lambda, p
hi) = (83-degrees, -100-degrees, 90-degrees); Mo = 3.0 x 10(21) Nm (Mw
= 8.3). The main rupture was preceded by about 10 sec by a cluster of
smaller events with a total moment of 1.2 x 10(20) Nm (Mw = 7.3). The
main rupture starts at about 20 km east or northeast of the initial b
reak, and propagates horizontally in the east to northeast direction.
The source duration is 40 sec, and the rupture dimension is about 40km
. If a fault area of 40x40km2 is assumed, the stress drop is 110 MPa.
An inversion of body waves (P, pP, and sP) with 6 basis moment tensors
yielded a best-fit solution with a 10% implosive component. This resu
lt is of marginal significance and its confirmation would require more
detailed information on the structures near the source region, pP bou
nce points and stations. The observed amplitude of the radial mode, 0S
0, (1226 sec) is consistent with a double couple model with less than
2 % isotropic component.