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## Kamchatka M8.8 Earthquake and Tsunamis Reach Across the Pacific to NSF’s OOI Regional Cabled Array Deborah Kelley1, Joe Duprey1, Wendi Ruef1, and W. Chadwick2 1University of Washington, 2Oregon State University On July 29 at 23:24:52 UTC, a powerful magnitude 8.8 earthquake struck the Kamchatka Peninsula in Russia, unleashing seismic energy and a tsunami that surged across the Pacific Ocean. This extraordinary event was captured in remarkable detail by the NSF Ocean Observatories Initiative’s (OOI) Regional Cabled Array—a seafloor observatory located offshore Oregon and Washington and one of the world’s most advanced underwater monitoring networks, with over 150 instruments transmitting real-time data to shore at the speed of light. At 23:33:15, the seismic waves from the Kamchatka earthquake reached Axial Seamount, located nearly 300 miles west of the Oregon coast and almost a mile beneath the ocean’s surface, having crossed the entire Pacific in just nine minutes. The vibrations were so intense they rattled a seafloor instrument continuously for over four hours (a,b). Then, at 06:03:00 UTC on July 30—6 hours and 30 minutes after the quake—the first tsunami waves arrived at Axial Seamount (c). Ultra-sensitive pressure sensor on bottom pressure tilt instruments picked up the waves with astonishing clarity. Lower-resolution sensors across the array also tracked the tsunami’s journey toward the UW west coast. Racing at speeds of 270 miles per hour, the first wave swept across the Juan de Fuca Plate and over the Cascadia Subduction Zone, eventually reaching seafloor monitoring instruments at the Oregon Shelf site just 14 miles offshore from Newport, Oregon. The OOI Regional Cabled Array instruments showed that the Pacific Ocean reverberated with smaller waves for several days after the first tsunami waves arrived—echoes of one of the most powerful seismic events ever recorded. This event highlights not only the dynamic nature of our planet and the seismic and tsunami hazards that we have to be prepared for in the Pacific Northwest, but also the incredible capability of modern science to observe and understand these kinds of events—in real time from deep beneath the ocean’s surface, and the value of such monitoring to coastal communities. ## Bottom Pressure and Tilt Meter Notes BOTPT LILY tiltmeter data (csvs) are curated by William Chadwick. The tilt units are microradians, or µrad. BOTPT-MJ03F-BPR-29July-to-01Aug2025-15sec.csv Date/Time, Pressure (psi) with tides, De-tided Depth (m) - from 29 July @ 00:00 to 01 August @ 00:00, and a record every 15 seconds (from the NANO bottom pressure sensor) BOTPT-MJ03F-LILY-tilt-data-29-30July2025-01sec.csv Date/Time, X-tilt, Y-tilt - from 29 July @ 00:00 to 30 July @ 23:13, and a record every 1 second (from the LILY tiltmeter) ## Where to find Additional Data Additional data from the included sensors prior to and after the event, or from OOI's many co-located sensors can be obtained through the OOI data portal https://ooinet.oceanobservatories.org/ , the OOI data explorer https://dataexplorer.oceanobservatories.org/ or OOI's M2M API service https://oceanobservatories.org/m2m/. ## Contact Information jduprey@uw.edu This material is based upon work supported by the Ocean Observatories Initiative (OOI), a major facility fully funded by the US National Science Foundation under Cooperative Agreement No. 2244833, and the Woods Hole Oceanographic Institution OOI Program Office.
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Drift Corrected Seafloor Pressure Observations of Vertical Deformation at Axial Seamount 2018–2021
Abstract Axial Seamount is a seafloor volcano with frequent eruptions and periodic cycles of inflation and deflation. Seafloor pressure gauges monitor vertical deformation with time, but inherent instrumental drift complicates and biases geodetic interpretation. A drift corrected pressure recorder was deployed on Axial Seamount on 6 July 2018, at coordinates 45° 57.29′ North latitude, −130° 0.56′ East longitude, depth 1,535 m. This system includes two independent quartz‐resonant pressure gauges, which nearly continuously observe the seafloor pressure. At regular intervals, the gauges are calibrated in situ with a modified deadweight tester at a pressure within 98% of the nominal seafloor pressure. Using the calibration data, the drift of each gauge has been modeled as a simple linear plus decaying exponential function of time. The two estimated linear sensor drift rates are 0.45 ± 0.12 and 0.36 ± 0.08 kPa/year; the modeled sensor drift represents a significant error if uncorrected. The standard deviations of the drift model residuals are of order 0.06 kPa or 6 mm depth equivalent. Once calibrated, the difference between the two seafloor pressure timeseries exhibits a RMS deviation of ±6 mm at the 90% confidence limit and a linear trend less than 1 mm/year. A time series from July 2018 to December 2021 tracks the inflation of Axial Seamount with differing inflation rates over different time intervals.
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- Award ID(s):
- 2021820
- PAR ID:
- 10396440
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Earth and Space Science
- Volume:
- 10
- Issue:
- 2
- ISSN:
- 2333-5084
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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