Post-earthquake losses: Devastating and costly
The 1995 Kobe earthquake, also in Japan, and the 2011 Christchurch earthquake in New Zealand provide insight into the devastation that liquefaction can cause. Liquefaction occurs when sandy soils that are partially or fully saturated are turned from solids to liquid by the stress exerted upon the material by the earthquake. The result: soils that suddenly lose their strength and integrity and flow as landslides; liquefaction is especially destructive to buildings, highways, and mountain communities, such as Christchurch, New Zealand.
In the past, fire has been the greatest contributor to damage following earthquakes. The 1906 San Francisco fire, created an inferno of property damage. Five-sixths of the total damage was due to fire, worth tens of billions of dollars in today’s market. Many of San Francisco’s Victorian-era mansions, shops and businesses, and infrastructure — indeed, whole neighborhoods — burned to the ground in the city by the bay. In 1923, again in Japan, a fire that erupted following the Great Kanto earthquake killed more than 92,000 people and was responsible for two-thirds of the total damage, amounting in today’s market to hundreds of billions of dollars.
High intensity earthquakes can also cause severe flooding. While most dams and reservoirs have been designed to withstand earthquake forces, but the simple lateral motion of an earthquake can cause natural and human-made structures to fail, and unload large volumes of water. Landslides can also block rivers and create ‘quake lakes,’ which can then flood settlements downstream, as happened in 2008 following the Sichuan earthquake in China. The authors say that of 6,800 plus dams and reservoirs worldwide, 623 are expected to have a significant shaking hazard within a return period of 475 years and that of these 333 are more than 45 years old and should be reassessed.
The authors further detail their process for disaggregating fatalities and damages resulting from secondary effects as compared to the actual shaking caused by the earthquake by presenting two case studies: the 2011 Tohoku earthquake and associated tsunamis and the 1960 Chile earthquake and tsunami sequence and landslides.
Frontierssays that as experts collect more data on secondary effects and resulting losses from high-intensity earthquakes, three benefits emerge. First, better models can be developed to understand the inherent risks and projected losses of building and living in certain areas. Secondly, scientists can reassess historic events, many of which were insufficiently recorded at the time. Thirdly, in this paper the authors demonstrate that to truly learn from these violent events data must be shared internationally and new technologies employed to process large volumes of information — otherwise, these tragedies appear as isolated, random events, rather than as natural disasters to which we can and must adapt.
— Read more in James E. Daniell et al., “Losses Associated with Secondary Effects in Earthquakes,” Frontiers in Built Environment (13 June 2017) (DOI: 10.3389/fbuil.2017.00030)
