Landfill Disaster: From 2011 Great East Japan Earthquake

Major earthquakes can cause sand-liquefaction of landfills as sand sediments are loosened by the great shock. This was noted after March 2011 Great East Japan Earthquake as 42 km² of Tokyo Bay Landfill coast was subsided by about 20cm (Konagai et al., 2012). Reports have even mentioned that some landfills have turned into mudflats (Chu and Ishikawa, 2011) (see Image 1).

Image 1: Tokyo Bay Landfill converted to mudflat (Source: Chu and Ishikawa, 2011)

When sand is liquefied, it acts as quicksand and weakens the integrity of the land beneath. Subsided land then results in uneven land surface and causes buildings o tilt. As sand spreads laterally outwards on the ground, pressure is placed on seawalls, pushing it forward by 2 metres (Konagai et al., 2012) (see Image 2).

Image 2: Seawalls pushed forward (Source: Konagai et al., 2012)

 The most worrying concern is the disruption of sewage treatment and drainage areas. When loosened sand accumulates and clogs up drainage pipes, flooding occurs. Houses and surrounding soils are then submerged in water for several months (Yanagisawa, 1993). The following video shows the land liquefaction caused by March 2011 earthquake.

Though the earthquake has compromised the integrity of buildings and structures, concerns over landfill leakage should be highlighted. I think that research should be conducted to evaluate the possibility of hazardous leachate leak and toxic gas escape from the landfills. Because Tokyo Bay is home to millions of people and there are various factories located there (Konagai et al., 2012), any waste leakage can directly expose people to environmental risk. Take for example, leachate leak can contaminate agricultural soil, which could then cause food poisoning when tainted crops are consumed. These are all long-term problems that might result from sand-liquefaction of landfill and Japan might not realize this till decades later. Hence, I urge the Japan government to conduct more in-depth environmental impact assessment on landfill liquefaction and start addressing any potential environmental pollution that arise from it.  

References

Konagai, K., Asakura, T., Suyama, S., Kyokawa, H., Kiyota, T., Eto, C., & Shibuya, K. (2011). Soil subsidence map of the Tokyo bay area liquefied in the March 11th Great East Japan Earthquake. Proc. Int. Sym. on Engineering Lessons Learned from the Giant Earthquake.

Chu, Kathleen, and Mariko Ishikawa. 'Tokyo Bay Home Demand To Sag After Quake Turned Land To Mud'. Bloomberg Business 2011. Web. Retrieved from http://www.bloomberg.com/news/articles/2011-04-13/tokyo-bay-home-demand-to-sag-after-earthquake-turned-land-to-mud

Kirby, Peter Wynn. Troubled Natures. Honolulu: University of Hawaiʻi Press, 2011. Print.

Yanagisawa E, Iai S., Wakamatsu K., Yamazaki J. and Yamazaki F. (1993) “Damage in Dagupan area.” Reconnaissance Report on the July 16, 1990 Luzon Earthquake, the Philippines, Japan Society of Civil Engineers, Series No. 1, 101-124.