Disaster in Japan
Chico State profs explain the science behind the devastating quake and tsunami
Russell Shapiro teaches a course on natural disasters at Chico State. So when the “Great Honshu Tsunami”—a term he’s casually coined—hit Japan and overwhelmed the country’s emergency-response systems last month, he was shocked.
“Japan is the most forward-thinking country in the world in terms of natural disasters,” he said in front of a packed classroom on the Chico State campus Monday (April 11). “And yet this happened to them.”
Shapiro was one of four Chico State professors who spoke at a special seminar titled “A Month After the Earth Moved: The Science Behind the Japan Disaster,” which was hosted by the Department of Geological and Environmental Sciences to explore what happened in Japan when the 9.0-magnitude earthquake and subsequent tsunami hit on March 11.
Geology professor Ann Bykerk-Kauffman kicked off the session with several videos of grocery-store shelves and skyscrapers shaking for several minutes during the quake.
She explained how “slip” on a fault—which occurs when rocks on either side of a fault slide past each other—made the ground shake. This geological process, combined with the deep-sea trench along Japan’s coastline, and its positioning (four of the earth’s plates come together near the country), make the country susceptible to extra-large quakes.
“Rapid slip on a fault causes the ground to shake because a huge amount of energy is released,” she said. She used a rubber band and other tools to demonstrate the “elastic rebound effect” that causes the earth to shake when faults can no longer bend into one another and rapidly break off.
What appeared to resonate most with the audience was Bykerk-Kauffman’s explanation of how “moment magnitude”—a formula used to measure the size of earthquakes in terms of the energy released—allows scientists to compare the Japan quake with others.
For example, the amount of slip in the 1906 San Francisco earthquake (which was about a 7.8 magnitude) was only 5 meters. In contrast, the amount of slip along the fault in the recent Japan quake is estimated to be a whopping 35 meters.
However, it was not the quake that caused thousands of deaths in Japan, Bykerk-Kauffman noted, segueing into Shapiro’s explanation of the tsunami.
“Nobody should ever die from a tsunami, period,” he began. “They are some of the most predictable natural disasters out there.”
High death tolls from tsunamis (also known as seismic or tidal waves) occur when populations are uneducated about warning signs or do not have emergency-response systems in place, Shapiro said. (That was the case in Indonesia in 2004, when a tsunami claimed the lives of 225,000 people.)
Many people are also unaware that tsunamis are tides (not one big wave) that recede and return several times. Many people who died in Japan last month were those who felt a false sense of security and left safe spots to survey damage between waves, he said.
Shapiro explained a few prediction models scientists use to estimate the height of impending waves, and described how tsunamis are scientifically measured, including with an open-ocean system in which buoys sit on the bottom on the ocean to measure the weight of the water on top of them.
Professor William Murphy, an expert on geologic disposal of nuclear waste, took the stage and hashed out a few scientific concepts, including radioactive decay, radiation and nuclear fission—a process that involves splitting nuclei to release energy.
He dispelled a few myths, including that nuclear power plants can blow up like a nuclear bomb. The breaking of the Fukushima Daiichi power plant, Murphy explained, is now considered the world’s third serious nuclear accident. (He referenced the others: the meltdown at Pennsylvania’s Three Mile Island in the late-’70s and the disaster in Ukraine at the Chernobyl Nuclear Power Plant in the late-’80s.)
Murphy described how the earthquake and tsunami took out Japan’s emergency power supply, causing the reactor to heat up and melt down, and spread radiation. Since then, elevated levels have been detected in Japan and worldwide, but Murphy says it’s too soon to panic. “Don’t worry about transportation of nuclear waste—it’s a waste of time,” he summed up.
Professor Greg Taylor wrapped up the seminar with a discussion about how radiation is carried through the atmosphere. He drew pictures to illustrate how evaporating water emits energy that causes elements to rise into the atmosphere.
“If something is moving upward, it has to go somewhere,” Taylor said. He explained how radioactive material becomes injected into jet streams—fast-flowing air currents that circle the Earth.
The seminar concluded with a brief question-and-answer session. One audience member asked about the possibility of a similar earthquake striking the West Coast.
Bykerk-Kauffman said the Cascadia fault—which stretches offshore from Canada to Northern California—tends to cause 9.0-magnitude quakes. That fault has a recurrence interval of about 400 years, and the last major quake was reported in 1700.
“It is going to happen,” Bykerk-Kauffman said. “We just don’t know when.”