Tsunami Debris Information

Debris Case Study #1:
Delays in recovery for Crescent City Harbor

Crescent City, California has experienced disproportionate impacts from tsunamis over the past 75 years compared to the rest of the U.S. West Coast ... More ❯

In 2011, a magnitude 9.1 earthquake off the coast of Japan generated a tsunami which nearly destroyed Crescent City Harbor. Damage to docks and boats caused a debris field which swirled around the harbor for many hours, and tsunami scour and sedimentation added to the environmental impacts. Contamination of water and sediment from petroleum products from damaged vessels led to immediate compounding hazards, long-term delays in rebuilding, and a substantial loss of revenue for the harbor over the past decade. 

Sunken/Damaged Vessels: Dozens of vessels evacuated from the harbor prior to the tsunami, but of the boats that remained, 16 sank and 47 were damaged. Sunken and damaged boats leaked fuel and other petroleum products, initiating careful monitoring by state and federal agencies. Fuel was extracted from the fuel tanks of the sunken boats over a period of several months. 

Sampling Sediments: State and federal regulatory agencies required sampling and testing of sediments for contaminants and to determine coarse-grained material content for offshore disposal, which is more cost effective than on-land disposal in a landfill. Sampling of the harbor sediment was put on hold for a number of months while regulatory agencies determined the best method to perform sediment collection and analyses. After a plan was in place, the regulatory review determined that tsunami deposits were of suitable grain-size composition and lacked significant contamination for disposal offshore of Humboldt Bay. This saved millions of dollars in disposal costs. 

Dredging: From September 2011 to mid-2012, the harbor extracted 150,000 m3 of material. Dredging delays significantly reduced harbor revenue needed to produce the harbor's matching funds required to obtain federal and state funds, a problem that will cause additional delays in harbor repair projects. 

Reconstruction: Reconstruction of the small-boat basin started in 2012 and continued until 2014, three years after the tsunami. Reduced revenue over this period extended delays in recovery. The local fishing fleet which had found other base harbors during reconstruction slowly came back over the past decade but financial recovery is still an issue for the harbor. However, tsunami resistant dock hardening, such as enlarging pile widths from one foot to three feet and constructing a current dissipation dock near the harbor entrance, have produced a more resilient harbor, evidenced by the lack of damage to the harbor during the January 15, 2022, tsunami generated by the Hunga-Tonga volcanic eruption. 

Future Considerations: Planning for tsunami debris and sediment could greatly reduce the impacts and long-term impacts in the future. Pre-tsunami preparedness and mitigation activities could include: 

• Developing a comprehensive plan which addresses environmental regulations, chemical cleanup and sediment sampling, and debris management and disposal.
• Strengthening of boat docks, piles, and infrastructure (fuel docks, sewage docks, etc.) to reduce damage could be undertaken prior to the next large tsunami, reducing impacts and recovery times.
• Consistent and effective dredging of sediment in areas of anticipated tsunami scour could reduce sediment accumulation and extraction.
• Extracting derelict vessels and moving commercial ships away from areas of high currents and/or offshore prior to the arrival of a distant tsunami could reduce the risk of compounding hazards (e.g., tsunami + contaminants).
• Shutting down fuel and sewage lines prior to the arrival of a tsunami could reduce the amount of potential contaminants released.

Back to beginning of this section  

Debris Case Study #2:
Challenges with tsunami debris removal in Japan

The Tohoku region of Japan experienced powerful and damaging tsunami flooding during the great earthquake and tsunami of March 11, 2011 ... More ❯

Tsunami heights reached tens of meters along the coast killing up to 20,000 people and heavily damaging coastal ports, industrial facilities, and business and residential areas up to several kilometers inland in some cases. For those who were fortunate enough to evacuate and survive the tsunami, the damage to the coastal communities prevented survivors from returning to their homes and businesses.  

The volume and distribution of debris scattered by the tsunami hampered response efforts in the weeks following the tsunami as well as recovery efforts which took years. Due to a shortage of land, waste management in Japan is a challenge even during normal periods. The generation of large quantities of disaster debris thus made the entire operation extremely challenging, both technically and financially. Officials had to update and develop debris plans on the fly and deploy assets immediately to help with debris removal. 

In 2012, the United Nations Environmental Program published a document summarizing how Japanese officials were addressing tsunami debris in the first year following the event (UNEP, 2012). It was reported that over 1,000,000 buildings sustained damage and over 22,000,000 tons of debris was produced during the tsunami. In the area surrounding the heavily damaged Fukushima-Daiichi Nuclear Power Plant, the situation was complicated by the release of radiation and contamination of debris. 

There was a phased approach to the debris strategies that had to be implemented: 

• In the hours-to-days following the tsunami, careful evaluation of damaged buildings and large debris patches was needed to search for survivors.
• In the days-to-months following the tsunami, the search for human remains throughout the debris was painstaking but necessary.
• Also, during this time, many residents were allowed to return to their property to collect personal items if the items had not been washed away. Where possible, local officials also collected personal items to make them available to the survivors and families of the victims.
• Over that first year following the tsunami, significant resources and guidance were made available to the local municipalities to address tsunami debris. The recommendation was that debris be separated and disposed of according to ten (10) categories of debris:
  1. Combustible waste – used for cement calcination process and power generation.
  2. Waste wood – make multi-purpose wooden boards and as fuel for power generation.
  3. Non-combustible waste – disposed at landfill site.
  4. Scrap metal – melted and recycled.
  5. Concrete waste – used as materials for reconstruction in impacted areas.
  6. Home appliances and automobiles – dismantled and separated into other categories.
  7. Watercraft – dismantled and separated into other categories.
  8. Hazardous wastes – disposed of according to hazardous properties of the debris.
  9. Tsunami sediment – used in cement, backfill in subsidence areas, or placed offshore.
  10. Waste at post-fire sites – melted or disposed of in landfills.

The tsunami debris removal and separation process took years to complete, as did overall recovery and reconstruction. There was a concern that after the recovery and reconstruction process that some communities would not repopulate as many people had moved away from the area for good. To help address this concern, provinces hired the local residents to assist with the debris removal and the rebuilding process to give them a sense of pride and a reason to stay in the region. 

Back to beginning of this section  

Debris Case Study #3:
“Precovery” planning for the next tsunami

On September 29th, 2009, a magnitude 8.1 earthquake occurred in the south Pacific off the coasts of the American Samoa, Samoa, and Tonga islands ... More ❯

The devastating tsunami triggered by this local earthquake caused 192 fatalities with 34 lives lost in American Samoa alone. Despite the best efforts of the U.S. government to quickly deploy assets to American Samoa, aide for response and recovery was delayed due to the isolated nature of these islands. This experience highlights the necessity for island communities to plan to be on their own in the hours, days, and possibly weeks following disasters. 

A decade after the 2009 tsunami, NOAA's Pacific Risk Management 'Ohana (PRiMO) held a conference titled: “Weaving a Path to Precovery in American Samoa.” “Precovery" is defined as “the process of preparing for recovery in order to speed the return to normality through short-term recovery and ensure that long-term recovery results in reduced risk, enhanced economic opportunity, and improved personal and ecological health.” The purpose of the conference was to work through a collaborative process to identify pathways to continue collective preparedness for future recovery efforts in American Samoa. This required extensive collaboration and coordination to ensure coherence among different governance structures (village councils, territorial government, and federal government), aims, objectives, sectors, plans, strategies, and tasks. 

Whether your coastal areas are isolated on an island or located along the coast of the mainland, the concepts of “precovery” should be applied to the clean-up of tsunami debris and sediment. Precovery could include both pre-tsunami planning and mitigation elements: 

• Develop a planning team comprised of government/tribal officials, debris experts, and members of the public will give all parties a voice in the process and help make the plan comprehensive in scope.
• Ensure all debris standards and regulations are well understood, methods to address these regulations are clearly laid out, and financial and non-financial resources required are included in the tsunami debris plan.
• Create tsunami debris teams to help implement the debris plan before (i.e., preparedness and mitigation) and after (i.e., response and recovery) the tsunami.
• Consider actions to take with debris immediately in the days and weeks following the tsunami (i.e., response) as well as long-term actions in the months after the tsunami (i.e., recovery).
• Integrate the tsunami debris plan into existing tsunami hazard mitigation, response and recovery planning documents.
• Develop memorandums-of-understanding (MOUs) for dealing with tsunami debris between governmental agencies and between government agencies and private companies who will help with tsunami debris clean-up.
• Implement mitigation strategies to reduce the volume or limit the impact of potential debris sources prior to help minimize recovery times.
• Review the tsunami debris plan every year and update it when necessary.

Precovery efforts will significantly reduce the immediate impacts from tsunami debris and improve the long-term resilience of the communities affected. 

Back to beginning of this section