THE JUNE 9 BOLIVIA AND MARCH 9 FIJI DEEP EARTHQUAKES OF 1994 .1. SOURCE PROCESSES

We examined the source characteristics of the 1994 deep earthquakes of Bolivia (June 9) and Fiji (March 9) over a period range of 1-1000 s u sing moment tenser and body wave analyses. Moment tenser inversions fr om 100-1000 s reveal that these two earthquakes were essentially point sources at very long period with insignificant isotropic and non-doub le couple components with scalar moments M(o), = 2.56x10(21) Nm for th e Bolivia and M(o) = 0.26x10(21) Nm for the Fiji earthquakes. Body wav e analysis for the Bolivia event reveals a 45 s duration, a nearly lin ear E-NE 1 km/s rupture on the subhorizontal focal mechanism plane giv ing a stress drop Delta sigma = 114 MPa. For the Fiji earthquake we fi nd a change in focal mechanism and a linear 3 km/s rupture plunging sh allowly to the north on the steep dipping nodal plane with a duration of at least 20 s and Delta sigma = 14 MPa. Both ruptures propagated pa rallel their null (sigma(2)) axis and suggests that their width is con trolled by the thickness of the seismogenic volume in deep slabs.