{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T20:54:48Z","timestamp":1782248088199,"version":"3.54.5"},"reference-count":26,"publisher":"American Geophysical Union (AGU)","issue":"B9","license":[{"start":{"date-parts":[[1997,9,10]],"date-time":"1997-09-10T00:00:00Z","timestamp":873849600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Geophys. Res."],"published-print":{"date-parts":[[1997,9,10]]},"abstract":"<jats:p>The <jats:italic>b<\/jats:italic> value of the frequency\u2010magnitude relation, and thus the mean magnitude, in the off\u2010Ito volcanic area is not uniform based on detailed <jats:italic>b<\/jats:italic> value tomography using about 10,000 events in an area of 10 km radius and in the upper 15 km of the crust. A high b value anomaly (b=15) below 7 km depth and with a radius of about 2 km, located below the coast southeast of Ito, contrasts with lower values of typically <jats:italic>b<\/jats:italic>=0.7 north of it and at shallower depths. On the basis of surface deformations, a tensile crack dislocation source was located above 7 km depth. Thus we surmise that the magma chamber in the off\u2010Ito area was located below 7 km depth. The correlation of a high <jats:italic>b<\/jats:italic> value anomaly with this model supports our hypothesis that active magma chambers may be mapped by high <jats:italic>b<\/jats:italic> value anomalies. The magma body may be described as consisting of two parts: a lower, well\u2010established chamber below 11 km depth and a shallower part (11\u20137 km depth). The <jats:italic>b<\/jats:italic> value in the volume surrounding the magma chamber increased from 0.7 during the 1980s to 1.5 during the earthquake swarms of the 1990s. This may reflect a trend of increasing crack density due to the intrusion activity.<\/jats:p>","DOI":"10.1029\/97jb01074","type":"journal-article","created":{"date-parts":[[2004,2,3]],"date-time":"2004-02-03T23:26:39Z","timestamp":1075850799000},"page":"20413-20422","source":"Crossref","is-referenced-by-count":162,"title":["Mapping active magma chambers by <i>b<\/i> values beneath the off\u2010Ito volcano, Japan"],"prefix":"10.1029","volume":"102","author":[{"given":"Max","family":"Wyss","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kunihiko","family":"Shimazaki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefan","family":"Wiemer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"13","published-online":{"date-parts":[[1997,9,10]]},"reference":[{"key":"e_1_2_1_2_1","first-page":"237","article-title":"Maximum likelihood estimate of b in the formula log N = a \u2212 b M and its confidence limits","volume":"43","author":"Aki K.","year":"1965","journal-title":"Bull. 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