‘Taking the pulse of the earth’
Print Edition
YUAN Lianfang’s work routine may look boring at first glance, but she finds it fascinating.
Working alone at the seismographic observatory based in No. 2 Songjiang High School, she collects data points at different times of the day.
“It’s like taking the pulse of the earth,” said Yuan.
Now 65 years old, she has been a seismic observer for 37 years, dedicated to the inexact science of earthquake prediction.
She uses a technique based on the theory that changes in groundwater radon may signal the onset of an earth trembler. Radon is a radioactive, colorless, odorless and tasteless gas. Its half-life is about 3.8 days, which means it can be observed only briefly before it decays.
One school of earthquake prediction hypothesizes that increases in radon concentrations are caused by new cracks in underground rock, allowing increased groundwater circulation that flushes out radon.
This effectiveness of the method is inconclusive. Scientific measurements of radon emissions near fault lines have found that earthquakes often occurred without any radon signal or didn’t occur when the radon signaled they should have.
With destructive earthquakes still cause human suffering and property destruction around the world every year, science is reluctant to give up on any possible prediction methods.
Each morning at 7, Yuan arrives at the observatory and takes a water sample from a deep well at the site. She first observes the bubbles and then lets the sample still for a while before measuring the radon concentration. During the day, she repeats the measurement procedure several times and logs the information on a chart.
“Statistics cannot talk, but to some extent, they are safeguarding Songjiang,” she said.
One day in November 2011, Yuan discovered an abnormal concentration of radon in water. She reported her findings to the Songjiang Seismological Bureau. After days of investigation, the radon buildup was attributed to construction work on Metro Line 9.
“I was relieved,” she recalled.
Her meticulous data collection has had corollary benefits. When Taiwan Semiconductor Manufacturing Co was researching where to site a new plant in Shanghai, one of its requirements was a stable substratum to prevent even the slightest wobble that might affect chip production. When the company reviewed the data Yuan had collected over the years, it decided to locate the plant in Songjiang.
In 2003, Yuan reached retirement age. The observatory advertised the job but couldn’t find a suitable replacement. So Yuan has stayed on, saying she will leave when the right person is found to take over.
“This job cannot vacant for even one day,” she said. “I’ve been working here for almost four decades. It’s very hard to leave.”
Shanghai no stranger to quakes
Shanghai doesn’t sit along a major seismic belt, but that doesn’t mean the city has escaped the capricious trembling of Mother Earth.
Over the past 500 years, Shanghai has survived more than 160 earthquakes, four causing considerable damage.
In 1624, a 5-magnitude earthquake damaged buildings in Shanghai. Forty-four years later, an 8.5-magnitude quake centered in the coastal province of Shandong, caused a surge in the Huangpu River in Shanghai, opened cracks on Chongming Island and badly damaged Liuguang Temple in the Jiading District.
Since 1970, Shanghai has recorded more than 10 earthquakes in the vicinity, including a 6.2-magnitude trembler in 1984 and a 6.1-magnitude quake in 1996.
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