To New Zealanders watching the 22 February 2011 earthquake disaster unfold it must have seemed like a really bad dream. To those in Japan three weeks later the shaking and the flood of sea water that followed seemed to never end. To the world the footage of houses shaking to pieces, high rises in Tokyo visibly swaying backwards and forwards and then a wave sweeping in from the sea and going effortlessly for kilometres inland, was the first indicator that a massive disaster was unfolding. The world rushed to help in both countries.
Four years later after those dark days, and after the Christchurch earthquake what have we learnt in New Zealand, and can we learn anything from the Japanese experience? We know from the mass of data that flowed from tidal stations and seismic sensors how the tsunami behaved, and why the damage varied so drastically from one location to another in Japan. In Christchurch we learnt the hazards that go with building on soils that are sandy in composition. But it is only a matter of time before both New Zealand and Japan suffer even bigger disasters, so how can both countries learn from their experiences?
In Christchurch the 04 September 2010 earthquake caused significant structural damage amongst older buildings, but thanks to the City Council use of coloured tags to identify the safety of buildings, the building collapses that caused fatalities five months later were limited to a handful of structures. Under Section 124 of the Building Act, green, yellow and red stickers were placed on buildings identifying their state after inspection by building inspectors. Unfortunately this also led to confusion, with communication break downs leading city council engineers to not properly identifying some buildings as being unsafe after significant aftershocks.
The lesson: Evaluating building safety is critical, but make sure the public know what the signage means
It is perhaps a tribute to the organization of Civil Defence and the investment in warning systems by the Japanese Government that tens of thousands more did not die on 11 March 2011. As soon as the quake began, hundreds of sensors detected the incoming seismic waves, interrupting television programmes, radio stations to broadcast warnings. What caused the disaster to be as bad as it was, was that many parts of the coastline subsided in the quake, increasing their vulnerability to the tsunami that would shortly strike – sea walls that had been built to 10 or even 15 metres high and which might have contained the waves subsided by up to a metre or more.
The lesson: sometimes not even purpose built structures will contain a really big event
Compared with the Haiti quake disaster thirteen months before the Christchurch earthquake, the Civil Defence response to the New Zealand events looked almost like large scale military drills with the precision it was carried out. By and large it was well run, but at specific sites there were some bad failures that cost lives such as at the Canterbury Television building which had collapsed. Emergency services were overwhelmed by casualties, communications were overloaded and aftershocks were hampering efforts. The wife of a civil engineer from Romania was working in the building when the quake hit. He was able to contact her by ringing her cellphone, and managed to maintain contact until about 0100 hours. Due to confusion over who should be in charge of the site relief operation, key decisions were not taken until too late. The wife of the civil engineer was one of 115 who died in the building.
The lesson: confusion is inevitable in the immediate aftermath, but listen to all sources of information
Although one could debate for hours the chain of events that led to the Fukushima reactor catastrophe, there are a few facts that are undeniable. The reactor survived the quake undamaged. The emergency shut down systems did kick in, only to be disabled by the tsunami before their job was even quarter done. The reactor began to heat up and eventually an explosion tore through Fukushima Dai-ichi (Fukushima No. 1). Whilst the reactors would not have cooled before the tsunami hit, the response from Tokyo Electricity Power Company since the meltdown has been a lesson in obfuscation, reluctance to admit loss of control of the situation and a failure to put together a comprehensive containment plan. In a country accustomed to order, the unusual sight of protesters demonstrating against the Government has been witnessed several times.
The lesson: transparency is everything – a loss of public confidence can be hugely damaging
Japan can reasonably expect a large (possibly magnitude 8.0-8.5)earthquake to occur on the tectonic plate boundary not far from Tokyo or Nagoya in the next hundred years, and remembering the painful experience of past events such as the 2011 event, but also the 1923 Kanto earthquake and the 1995 Kobe earthquake, the onus goes on Japanese authorities to make themselves more accountable to the public. New Zealand can also expect another, bigger disaster in the next 100-150 years, with the Alpine Fault expected to release a magnitude 8.0-8.3 event, numerous little known faults in Cook Strait and the ever present risk that the next one might be a failure of the Hikurangi Trench subduction zone. Any one of these would be hugely damaging. And the latter two could present a tsunami…