Evidence of a tilted volcanic conduit?

This is my AGU 03 presentation about the precursory seismicity of the 1999 eruption. Hypocenters of deep LP events (2-12 km depth) suggest that there is an inclined conduit that feeds a magma chamber located about 4 km depth beneath the caldera. Deep LP events were the first seismic signs of an eruption, preceding magmatic activity by ~2 years.