By Rick Wilson, California Geological Survey (CGS)
Many of my tsunami and non-tsunami colleagues can remember what they were doing on March 11, 2011, the day the magnitude 9 Tohoku-Oki earthquake struck offshore of Japan, unleashing a tsunami that devastated Japan and reached California’s shore. They typically can relate what this event meant to them at a personal, professional, and emotional level. This is what the event has meant to me.
A Tsunami Scientist’s Response in California
It was the first tsunami which most people who were not personally impacted could observe in real-time on television. As a CGS tsunami scientist, I took part in federal, state, and local tsunami warning coordination calls, helping to answer questions from local emergency officials in California who were planning their tsunami response activities.
CGS sent five field observers to select harbors during the event to note the impacts in California in real time. Eight field teams were formed after the event to collect data and evaluate tsunami impacts.
Witnessing Tsunami Impacts in Japan
Five months after the tsunami, USGS colleagues invited me to join a field reconnaissance team evaluating tsunami deposits and impacts throughout the Tohoku region of Japan.
As a scientist, the most memorable location our team visited was Aneyoshi Bay in Miyako, Iwate Prefecture, where the highest tsunami run-up elevation (130 feet) was observed.
I remember sitting on the beach removing pebbles from my boots, looking up 80 feet above my head to a spot where the tsunami had denuded the vegetation. The V-shaped entrance to the bay and valley topography funneled the tsunami inland and upward simultaneously in an aggressive fashion.
A Return to Japan to Study Recovery
My second trip to Japan was with a multinational group supported by the Earthquake Engineering Research Institute and interested ongoing recovery efforts.
On March 11, 2013, I visited the site of the Okawa Elementary School near Ichinomaki, Miyagi Prefecture. Memorial services were taking place to honor the 74 children and 10 teachers who perished two years earlier in the tsunami.
A hill close to the school could have provided safety, but indecision and delays about what action to take led to this catastrophic loss of life.
What Tohoku-Oki Teaches California
Never forgetting the losses, the lessons we learned from the Tohoku-Oki event led to many new ideas and products to help local officials with their tsunami preparedness, mitigation, and recovery planning efforts.
In California, CGS worked with the USGS and Humboldt State University to perform a statewide field reconnaissance to investigate potential tsunami deposits. This project led us to update tsunami hazard maps.
We worked with the University of Southern California to develop decision-support tools called “playbooks” to plan for tsunamis of different sizes from different regions of the Pacific.
Our analysis of the Tohoku-Oki event and our partnerships with the California Governor’s Office of Emergency Services and the California Tsunami Technical Advisory Panel helped us create products and guidance for mitigation and recovery planning that will hopefully reduce future tsunami impacts in California communities.
Some of this work contributes to guidance from the National Tsunami Hazard Mitigation Program to help communities and other U.S. states and territories with their preparedness work.
Ten Years Later
On this 10th remembrance of the Tohoku-Oki earthquake and tsunami, the Department of Conservation’s California Geological Survey invites you to explore a suite of products we’ve created to share more detail on this event and our lessons learned.