The structure of the seismic refraction model, M-1, depicted in the framework of the converging plates. The zone of shallow earthquakes defined by the local networks (Figs. 3B-E, 4) is indicated, it dips 40-60 degrees islandward. I argue that the shallow earthquakes (above the downgoing plate) in the zone relate to the RTB-thrust. Deeper earthquakes are thought to relate to stresses in the plate. A positive ~150 mGal free air gravity anomaly occurs islandward from the RTB-thrust. It is not known whether the anomaly relates to the upthrust mantle or to shallow features in the crust, such as basaltic intrusives.

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