Double Seismic Zone for Deep Earthquakes in the Izu-Bonin Subduction Zone

Science  25 Feb 1994:
Vol. 263, Issue 5150, pp. 1116-1118
DOI: 10.1126/science.263.5150.1116


A double seismic zone for deep earthquakes was found in the Izu-Bonin region. An analysis of SP-converted phases confirms that the deep seismic zone consists of two layers separated by ∼20 kilometers. Numerical modeling of the thermal structure implies that the hypocenters are located along isotherms of 500° to 550°C, which is consistent with the hypothesis that deep earthquakes result from the phase transition of metastable olivine to a high-pressure phase in the subducting slab.