Abstract Details

Details of the Abstract

Title of paper Conductivity anomalies in the deep subsurface of central Hokkaido
List of authors T. Hashimoto, J. Pan, A. Suzuki, M. Takada, K. Okada, R. Tanaka and M. Tamura
Affiliation(s) Hokkaido University,
Hokkaido University,
Hokkaido University,
Hokkaido University,
Hokkaido University,
Hokkaido University,
Res. Inst. Energy, Environment and Geology, Hokkaido Research Organization
Summary Central Hokkaido is known for its active volcanic activity, with Mount Tokachi having experienced three magmatic eruptions in the 20th century and being closely monitored. However, understanding the deep subsurface structure, especially the electrical conductivity below 10 km, remains a priority for research. A recent magnetotelluric (MT) survey by Iwama (2022) suggested a large conductive body in the lower crust of Central Hokkaido, although based on a single profile and requiring validation.
To confirm these findings, new MT arrays were deployed from 2022 to 2023 to the north and south of the original transect. Incorporating data from a total of 50 sites, the modeling revealed a significant conductive anomaly spanning 20-40 km deep and 40 km wide between the Conrad and Moho discontinuities. This anomaly coincides with the volcanic chains of the region, including active volcanoes Mount Taisetsu and Mount Tokachi, associated with deep low-frequency earthquakes. It also correlates with seismic low velocity anomalies.
The presence of this conductor suggests possible fluid involvement from the subducting Pacific Plate, influencing volcanic activity and crustal dynamics. However, further quantitative assessments are necessary to fully comprehend its implications. This discovery opens new avenues for understanding the geological processes and volcanic hazards in Central Hokkaido, emphasizing the importance of ongoing research into the region's deep subsurface structure and its impact on volcanic behavior.
Session Keyword 4.0 Tectonics and geodynamics, including magmatism
File upload 4.0_conductivity_anomalies_in_hashimoto_01.pdf
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