The whole rock composition of submarine lave from June 27 eruption overlap the compositional range of volcanic products erupted in 1983. This may indicates magma erupted on June 27 is originated from the same magma source as the magma erupted in 1983.

On the other hand, the whole rock composition of six lapilli from August 18 eruption differ significantly from those found in historic eruption products. Mass balance calculation suggests that some accumulation ( ~15%) of plagioclase to their parental magma can account for the difference between the composition of lapilli from August 18 eruption and those of historic volcanic products. Another interpretation is that new extraordinary magma, which is rich in Al2O3 and CaO, ascends, while preceding magma of June 27 eruption is pushed away.

All oxide determined by XRF.