NanTroSEIZE

Observatory Data Portal

Welcome to the NanTroSEIZE pore pressure observatory data portal! This portal provides access to interactively visualize and download pore pressure data from IODP Site C0002, located in the Nankai Trough, above the active seismogenic subduction plate boundary offshore SW Honshu, Japan. Data are available from two pressure sensors monitoring the subsurface rock formations: one within the uppermost accretionary prism (937-980 meters below seafloor; mbsf), one in the overlying Kumano Basin fill sediments (757-780 mbsf). In addition, pore pressures are available from a seafloor reference sensor, and a subsurface sensor that is cemented in the hole with a tiltmeter, strainmeter, and seismometer (not in hydraulic communication with the formation). For more details, check out the "about page."

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Recent Notable Events

Magnitude 6.2 Omachi Earthquake

The M 6.2 Omachi earthquake occurred on Nov. 22, with a hypocentral depth of 10 km.

Drilling perturbation!

During IODP Expedition #348, we revisited and deepened riser drill site C0002N, located approximately 100 m East-Northeast of the observatory site C0002G. Pressures at the seafloor remain unchanged, whereas formation pressures exhibit a clear response to the drilling activity nearby. The response is complex, and include initial small increases in pressure (just prior to the large spikes in pressure highlighted here, and best viewed after removing the tidal signal), followed by large pressure spikes that decay over time. The large changes in pressure coincide with significant mud losses in the riser hole. We interpret the early response to reflect a typical response to fluid injection and pressure diffusion, whereas the latter responses likely indicate propagation of fracture and concomitant translation of pressure away from the riser hole. We are currently analyzing this response in more detail to quantify formation hydraulic properties.

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