重力のインバージョン Gravity Inversion
Inversion of potential fields such as gravity has inherent non-uniqueness when it is used for estimating subsurface density structure. The ambiguity could be overcome, at least partially, (1) by using <I>a priori</I> information (such as pointwise drilling data) and (2) by incorporating independent observations (such as geomagnetic anomaly and seismic data). We present several examples demonstrating how gravity inversion is applied for retrieving geologically interesting features (meteor crater, salt dome, volcano, active fault <I>etc</I>.). We emphasize that cooperative inversion should be used whenever possible to obtain better resolution on the underground structure.<BR>Recent advance of the gravity change theory enables us to discuss how to model seismic and volcanic events from gravity change data. Since gravity is sensitive to migration of matter under the ground, gravity inversion is useful in estimating flows of water and magma during such events. Joint inversion of gravity data with conventional crustal movement data proves to be quite effective in modeling the 1989 earthquake swarm and submarine eruption, off Ito.
地學雜誌 104(7), 1047-1062, 1995-12-01
Tokyo Geographical Society