At 9:46:23 PM Pacific Time on March 10, 2011 (05:46:23 UTC on March 11), a magnitude 9.0 earthquake occurred 129 km (80 miles) off the coast of Sendai, a city in Honshu, Japan. The earthquake triggered a catastrophic tsunami that produced a wave height of at least 7.3 m (24 ft), which propagated throughout the entire Pacific Ocean basin. Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys positioned around the Pacific Ocean provided real-time data of the impending tsunami as it travelled across the ocean towards the US West Coast. For example, DART buoy 21418 located 833 km (517 miles) NE of Tokyo in 5.68 km of water depth, recorded a 2 m wave. This system provided warning of the tsunami within a half hour after the earthquake.
Because of this warning, coastal communities in Washington and Oregon were evacuated by the time the tsunami hit the US West Coast almost 9 hours after the earthquake occurred. Harbors along the Oregon coast, including Depoe Bay, Coos Bay, and Brookings, and in Crescent City, CA have reported damage to docks and boats in the harbor. Much of the damage was caused by the massive amount of water that was surging in and out of the harbors very quickly.
For more details about the earthquake and the impact of the tsunami in Japan and the Pacific Northwest, please see the OR Dept. of Geology and Mineral Industry's (DOGAMI) Winter 2012 newsletter, Cascadia - The 2011 Japan Earthquake and Tsunami: Lessons for the Oregon Coast
NANOOS Tsunami Products and Response
The Tsunami Evacuation Zones for the Oregon Coast application was developed jointly by the Oregon Department of Geology and Mineral Industries (DOGAMI) and NANOOS. Based in Google Maps, this tool allows residents, planners, emergency responders, and others to see the extent of areas affected by both local (Cascadia subduction zone) and distant (outside of the immediate Pacific Northwest region) earthquakes and tsunamis. Inundation areas for Cannon Beach and the southern coast from Brookings to Bandon were recently updated, and this tool will be expanded to include Washington coastal areas within a year.
NANOOS saw traffic spike 400% on March 11th, the day of the Japan earthquake, with nearly all of that traffic directed towards the Oregon Tsunami Evacuation Zone application. Of the almost 500 page views, most of the visitors were from Washington, Oregon, and California, but we had visits from nearly every state, including Nebraska. Of the traffic, 76% visited directly (by either typing nanoos.org directly into the address bar or using a bookmark), 6.5% came from Google, 4% from Facebook, and 3.25% from IOOS.
The NANOOS Data Management and Communications (DMAC) team saw that this high traffic was resulting in frequent outages of the tsunami inundation zone application. The Geoserver that we had been using was not able to fulfill all of the data requests. In response to this, staff members moved the shape files to a more robust tile server housed at the Environmental & Information Systems Department at the Applied Physics Lab at the University of Washington. Future plans include making these shape files available through the NANOOS Visualization System (NVS).
The NANOOS Visualization System (NVS) is home to real-time data relevant to tsunamis, including surface currents and water height, as well as other information that is collected by sensors that are supported by a wide range of organizations, including the NOAA National Data Buoy Center (NDBC), NOAA National Ocean Service (NOS)/ Center for Operational Oceanographic Products and Services (CO-OPS), and NANOOS. Users can easily access these data that are collected from several locations in Washington, Oregon, and Northern California.
The NANOOS Facebook page was also used to get the message about the tsunami out broadly. Throughout March 11th with updates on March 14th, water level graphs from La Push, WA (northern/central coast), Garibaldi, OR (northern coast), Port Orford, OR (southern coast), and Crescent City, CA (northern coast), among other locales, were posted on the page. Both real-time data graphs and Comparator graphs, which show predicted model output and observed measurements on one graph, were posted. Resources from other organizations, including tsunami predictions and visualizations from the NOAA Pacific Marine Environmental Laboratory (PMEL) were also posted.
Reports from NANOOS Personnel and Members
From Jonathan Allan, NANOOS Principal Investigator, NANOOS Chair of the User Products Committee, and Coastal Geomorphologist at the Oregon Department of Geology and Mineral Industries (DOGAMI) and Rob Witter, Regional Coastal Geologist at DOGAMI:
"The following plot shows the residual 1-minute water levels, or the difference between the predicted and the measured tide, for multiple tide gauges along the Pacific Northwest coast (northern WA (La Push) to northern CA (Humboldt Bay/North Spit) from 7am to 4pm on March 11th. The data in these graphs show the alongshore varying response in water levels, characterized by a progressive increase in the water levels (non-tidal residuals) from the Garibaldi gauge in northern Oregon southward to Port Orford and ultimately Crescent City, where the largest waves were observed, and a similar increase in residuals, albeit much smaller, from Astoria northward into northern WA with the largest waves observed at La Push. Crescent City, CA was the hardest hit city in the NANOOS region. Also of interest, the tsunami waves remained large throughout most of the day on March 11, reinforcing the importance of staying off the beaches and away from low-lying areas during these events until the all-clear is sounded by emergency managers."
From Steve Rumrill, NANOOS Principal Investigator and Research Program Coordinator for the South Slough National Estuarine Research Reserve in Coos Bay, OR:
"Our NERR/SWMP/NANOOS data loggers are still in the water and the sensors are fully operational. The real-time GOES telemetry transmissions are intermittent and are not working right now, but the time-series data are captured by the internal memory inside the sensors. We will let the tsunami surges complete their reverberations for another day and then retrieve the data loggers and download the water-level data on Tue-Wed."
The tsunami surges entered Coos Bay and South Slough Friday morning with an amplitude of about 3-5 ft, and the surges were repeated throughout Friday and Saturday followed by diminished surges on Sunday-Monday. The photo on the left shows the tsunami surge sweeping over the Charleston Boat Launch dock as it flows up into the inner boat basin. The photo on the right shows the boat launch dock submerged again as the tsunami surge flowed back out of the inner boat basin. The tidal channels of South Slough also filled and drained rapidly numerous times over the weekend, but we did not experience any standing waves. Stay tuned for some graphics that illustrate the timing and amplitude of the tsunami surges in South Slough.
From Pat Corcoran, NANOOS Governing Council and Education & Outreach Committee member, and Coastal Hazards Outreach Specialist for Oregon Sea Grant:
"The official emergency response on the North coast went well and there was no damage."
His worry is that, yes, we were prepared for a 9 hour warning of a 2 foot tsunami (on the North coast) occurring during an 8 foot ebb tide, but what about when the earthquake happens here? The latest estimate of the probability of a 9.0 or greater magnitude earthquake occurring in the Cascadian Subduction Zone just off the coast of Oregon and Washington is a 37% chance that it will occur in the next 50 years. When this earthquake occurs, people in coastal areas will have 15-30 minutes to get to ground that’s higher than 50 feet elevation. Are we prepared for what we saw in the tsunami videos from Japan? We still have a lot of work to do, including identifying the safe high ground along the coast, especially near populated and popular areas, and increasing access and assembly areas at those sites. Some of this work includes clearing dense blackberry and salal from these areas.
Other Earthquake and Tsunami Resources for
Oregon and Washington
Other Resources about the March 11th Honshu
Earthquake and Tsunami