Pulsing Seismic Waves (02:32)
Long period pulses were detected during the 2016 earthquakes in southwest Japan. If they had struck skyscrapers, current safety technologies could not prevent lateral sways, five times what the buildings are designed to endure.
Kumamoto Quake (04:59)
In April 2016, powerful earthquakes created a 30 kilometer ground fissure; seismographs recorded intensity seven waveforms ten seconds after. Using event data in computer simulation reveals that long period pulses would deform skyscrapers.
Great Eastern Japan Earthquake (03:43)
In March 2011, long seismic waves hit Tokyo, causing skyscrapers to sway for minutes. Long period pulses jolted upper floors, giving movement momentum. Engineers responded, installing dampers and pendulums in high rises.
Chichi Earthquake Comparison Study
In 1999, long period pulses and an 80 kilometer ground fissure was recorded in Taiwan; surface breaks also occurred during the Kumamoto event. Quakes on active fault lines that produce crevices are connected to the waveform phenomenon.
Susceptibility to Natural Disasters (04:17)
The Kumamoto earthquake revealed a new risk to cities across Japan. With 113 active faults, an event could occur at any time. Long cycle movements specifically put skyscrapers in danger. Osaka, built on the Uemachi Fault Zone, is particularly vulnerable.
Event Dramatization (06:39)
Thousands of Japanese live in high rises. If Osaka skyscrapers were hit with long period pulses, buildings would be compromised, and residents required to evacuate. Fires would break out across the city; 340,000 people would be displaced.
Safety Precautions (07:35)
In Tokyo, high rise building managers attend a Disaster Prevention Study Group, learning risks of evacuations. Some implement emergency communication and community help systems. Awa is demolishing all structures built over fault lines.
Hidden Dangers (05:41)
Professor Daigoro Isobe studies long period pulses, finding densely packed cities vulnerable to adjacent building collisions. Seismic base isolators are effective during typical earthquakes, but sharp jolts caused by long cycle movements would cause them to sway high rises into neighboring buildings.
Creating Solutions (07:05)
At Hyogo Earthquake Engineering Research Center, scientists develop floating city designs, prohibiting lateral and vertical vibrations. In Handa, Yasui Architect and Engineers incorporates base isolators with dampers, acting as breaks to reduce shaking and mitigating damages from long period pulses.
Credits: Skyscrapers in Aseismic Danger (00:60)
Credits: Skyscrapers in Aseismic Danger
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