Building fixes and education are key, seismologists say
WESTON - In a one-story brick building built on bedrock, John E. Ebel monitors the size and heft of small earthquakes that rattle parts of New England every year.
For three decades, the Boston College professor and seismologist has recorded quakes around the region, sticking red pins into a large map that displays tremor clusters from Maine to Rhode Island. He distributes the information to a network of seismologists worldwide and worries, always, about what could happen if a damaging earthquake strikes New England.
“We definitely have the potential,’’ said Ebel, 56, director of Boston College’s Weston Observatory, a geophysical research laboratory. “We don’t know when the next earthquake will strike.’’
The earthquake that devastated Haiti Jan. 12 has provided Ebel the spotlight to tell anyone who will listen that such an event - although rare - could also hit this part of the United States. He’s part of a growing group of researchers, emergency management specialists, and structural engineers readying for such a local catastrophe and debating how much realistically can be done to reduce risks.
Like Ebel, they wonder what a substantial jolt would do to the region’s many old brick buildings - including schools and fire stations - which were not built to modern seismic codes and, in many cases, are sited on old landfills that amplify ground vibrations.
“A small shake is fine. If there is anything of serious seismic intensity in the range of 6.0 or higher on the Richter scale, we’ll have havoc around here,’’ said structural engineer Mysore Ravindra, president of LeMessurier Consultants in Cambridge.
The magnitude of an earthquake is determined by the size of its seismic waves, or ground shaking, measured on the Richter scale, which was devised by Charles Richter of the California Institute of Technology in 1935. The measure is based on a logarithmic scale, which means that for each whole number increase on the scale, the amplitude of the ground motion on a seismograph goes up 10 times. The recent earthquake in Haiti was a magnitude 7.
No one is suggesting there is cause for panic. The last major earthquake here occurred in 1755 off Cape Ann, an estimated 6.3 temblor that was felt from Nova Scotia to Maryland. Californians in one year experience the same number of earthquakes that happen over a century in New England, Ebel said. But that doesn’t mean a damaging earthquake couldn’t happen today. Before last month, a major quake had not hit Haiti since 1897.
“It is something we take seriously,’’ said Peter Judge, spokesman for the Massachusetts Emergency Management Agency, which stages earthquake-related training every few years. “The worst-case scenario is an earthquake in wintertime.’’
New England sits on the center of the North American tectonic plate, one of nine large plates that make up the earth’s crust. While many earthquakes occur along plate boundaries, such as in California and Haiti, in New England they happen on faults that are reactivated as the earth is squeezed by plates along the West Coast and mid-Atlantic states. About 20 small quakes affect New England annually; the largest recent one was a magnitude 4.2 in 2006 near Bar Harbor, Maine.
New England bedrock is also colder than earth along plate boundaries, so it more efficiently transmits seismic waves. That means vibrations could possibly affect a larger region, Ebel said.
A Cape Ann-size earthquake centered in downtown Boston could cause $42 billion in losses and 1,300 deaths in Massachusetts, according to a 2006 study by the Northeast States Emergency Consortium, a nonprofit based in Wakefield.
“I’d be most concerned about the areas that have the worst soil conditions combined with some of the older red brick unreinforced masonry that we see in older areas,’’ said Edward Fratto, executive director of the consortium. “A lot of those buildings are schools, fire stations, hospitals.’’
Structures built after 1975 - when Massachusetts created a statewide building code - were made to withstand major earthquakes. In 1997, the code was strengthened to ensure that buildings undergoing major improvements are examined and made safer, said Joe Zona, a structural engineer and chairman of the state Seismic Advisory Committee, a group that makes recommendations to the State Building Code.
One- and two-family homes are excluded from the building requirements. But Zona said most homes would hold up well in a quake because they are generally bolted to foundations and built with flexible wood frames that would mean they would bend, rather than collapse, in an earthquake.
That still leaves tens of thousands of larger buildings across the state built before the 1970s that could be damaged. Ravindra, who also sits on an advisory committee for the state Board of Building Regulations and Standards, said most of Boston’s taller buildings were built after 1975 or constructed to withstand heavy winds that are stronger than most earthquakes. Typical masonry buildings, however, like the stately brick buildings along Beacon Street, Marlborough Street, and Commonwealth Avenue in the Back Bay, could take “a big beating,’’ he said.
The challenge is to persuade private owners to launch expensive retrofitting projects to prepare for a calamity that may not occur for centuries, if at all. “Unless you make funds available, you can not mandate’’ such work, Ravindra said.
For now, Ebel is just glad to have people talking about the subject. He works with state and federal officials to talk about risks and what can be done. He says a statewide program to educate school children - who often remember such lessons all their lives - could be a wise investment.
As part of such an education, they would learn that homeowners should secure water heaters, bolt houses to their foundations, review insurance policies, and make a family plan to reunite after an emergency. During an earthquake, they would be told, stay away from windows and bookcases, and remain inside until the shaking stops - under a heavy table or desk, if possible.
Ebel also wants developers to take earthquake risks seriously and adhere to state seismic safety requirements. Each time an old building is refurbished or taken down, he said, the state becomes safer. “We are getting more prepared all the time,’’ he said
By Jenifer B. McKim for Boston Globe February 2, 2010
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