The prime purpose of this book is to present a new insight into the shallow and deep structure of the earth beneath Japan Islands. It is a deep penetration inside the earth down to 700 km depth exhibiting interesting images and distinctive information on the complexity of the shallow and deep velocity structure. This book revealed important results about volcanoes; Pacific slab destiny beneath Japan; Philippine Sea slap behavior; dehydration process; slab stagnation; and many others. How did these slabs reach this depth? And, are they responsible on the active volcanoes in this region? Does water exist at this high temperature and pressure depth? Do the sea mounts effect the slab subduction rates. The answer of these questions and is given in this book in detail, Have a nice reading !!