Exploring Local Seafloor Pressure Changes Along the Nankai Trough: Insights Into Fluid Reservoir Dynamics
Description:
The Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) is a system of seafloor sensors that monitors earthquake and tsunami activity. Observations from this network, positioned above the area where the 1944 Tonankai earthquake originated, have shown that slow slip events (SSEs)—a type of gradual tectonic movement—occur in the shallow areas of the fault where megathrust earthquakes take place. However, these SSEs have mostly been detected near the D-node of the network, with only a few exceptions. For instance, one study reported detecting an SSE near the B-node, but other related phenomena like low-frequency tremors or very low-frequency earthquakes haven’t been observed there yet. This is likely due to the way the network’s sensors are distributed.
Most of the sensors that measure crustal deformation are arranged in a straight line between the C and D nodes, which doesn’t cover the B-node area well. Additionally, the geology near the B-node is unique. Studies suggest that a seamount (an underwater mountain) has been pushed beneath the continental plate in this area, and that fluids are moving upwards through faults and mud volcanoes.
In this study, we explored an alternative explanation for a pressure change detected near the B-node in 2013. Our analysis suggests that the pressure change could be due to local changes in cylindrical fluid reservoirs. These reservoirs might be connected by pathways that temporarily opened due to changes in ocean conditions. This finding highlights the importance of closely monitoring ocean activity and studying the structure of the seafloor to better understand and detect these kinds of pressure changes.
Session: ESC-SSA Joint Session:Seismology in the Global Oceans: Advances in Methods and Observations [Poster]
Type: Poster
Date: 4/15/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Keisuke
Student Presenter: No
Invited Presentation:
Poster Number: 2
Authors
Keisuke Ariyoshi Presenting Author Corresponding Author ariyoshi@jamstec.go.jp Japan Agency for Marine-Earth Science and Technology |
Akira Nagano nagano@jamstec.go.jp Japan Agency for Marine-Earth Science and Technology |
Takuya Hasegawa hasegawa.takuya@met.kishou.go.jp Japan Meteorological Agency |
Hiroyuki Matsumoto hmatsumoto@jamstec.go.jp Japan Agency for Marine-Earth Science and Technology |
Narumi Takahashi narumi@bosai.go.jp National Research Institute for Earth Science and Disaster Resilience |
Takane Hori horit@jamstec.go.jp Japan Agency for Marine-Earth Science and Technology |
Tatsuya Aso tatsuyaa@jamstec.go.jp Japan Agency for Marine-Earth Science and Technology |
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Exploring Local Seafloor Pressure Changes Along the Nankai Trough: Insights Into Fluid Reservoir Dynamics
Category
ESC-SSA Joint Session:Seismology in the Global Oceans: Advances in Methods and Observations