Lisbon's 1755 Earthquake a Warning for Today

Lisbon's 1755 earthquake a warning for today
By Barbara Cornell
Wed Oct 26, 2:43 AM ET

LISBON (Reuters) - The aftershocks of a truly epic earthquake are measured not by magnitude or distance but by centuries.

Exactly 250 years after one of the world's most devastating quakes transformed regal Lisbon into a ghost town, experts from around the world will gather to find a prologue for the future.

The earthquake that hit Lisbon on November 1, 1755, rang Paris' church bells and triggered a tsunami from Norway to North America. It sent shockwaves through Enlightenment Europe, changing forever the way earthquakes were perceived and handled.

"We have to call attention to the authorities and the population in general that this past event, this terrible event, may come again," said Carlos Sousa Oliveira, president of the Portuguese Society for Earthquake Engineering.

"We don't know when. It might not be as strong. But we have to prepare to face it."

About 200 seismologists, engineers, architects, urban planners, historians, and even philosophers are expected at a four-day conference here, beginning on the November 1 anniversary.

Experts will present testimony from this month's killer South Asian quake and lessons from recent disasters, such as northwestern Turkey in 1999 and the Indian Ocean in 2004.

They will discuss research and preparedness in earthquake-prone countries, like Japan, Italy and Russia, and try to raise awareness of danger elsewhere.

"People living in Portugal have no idea of the risk. They are not aware of the risk because earthquakes have a long return period, meaning they can take hundreds of years to happen again," said Alfredo Campos Costa, an earthquake engineer working in seismic risk assessment research.

Experts concede that knowledge means little unless it is applied, and that the most potent argument for change, such as designing safer buildings, is the memory of previous disasters.

"It's folk memory rather than regulation that decides how people build," said Robin Spence, a professor of architectural engineering at Cambridge University and president of the European Association for Earthquake Engineering.

FIRST MODERN DISASTER

Before the conference, experts will hold a one-day workshop on October 31 to draw up a Europe-wide strategy to deal with the risk of quakes.

"We don't know exactly what are the most prone areas in terms of seismic risk and worse, we don't know how to mitigate this risk," said Campos Costa.

"If something happens like the 1755 earthquake today ... all of Europe is going to pay because we are all united at the economic level ... Europe is nowadays like a city," he added.

The 1755 earthquake, which also devastated Morocco and claimed around 70,000 lives, shattered the prevailing optimism that this was the best of all possible worlds.

Scientists say it was the first modern disaster, with coordinated emergency responses and a reconstruction plan that was drawn up with a possible, future disaster in mind.

"The event and the administrative organization afterwards can be regarded as the beginning of seismology, because it was the first time that a government took responsibility for disaster management," said Karl Fuchs, a geophysics professor and former director of the Geophysical Institute at the University Fridericiana at Karlsruhe, Germany.

BURNING CANDLES, BROKEN BUILDINGS

The earthquake struck on a sunny Saturday in Lisbon, one of Europe's richest cities and an international trading center.

Tremors, so violent that they stirred waters off Finland, toppled buildings and set off a devastating tsunami that swept through the city's center. Fires, blamed on church candles, burned for six days. Aftershocks continued for nine months.

The earthquake, estimated at 8.75 on the Richter scale, knocked down all but 3,000 homes and ruined 53 palaces, 32 churches and 46 monasteries and convents. Today the skeleton of the Convento do Carmo still haunts the Lisbon skyline.

The quake's epicentre and magnitude are still debated. But what is certain is how quickly the authorities responded.

"Bury the dead and feed the living," are words attributed to Sebastiao Jose de Carvalho e Melo, the Marques de Pombal who was Portugal's virtual dictator at the time and whose statue gazes from a major traffic circle toward the city he rebuilt.

Under his direction, Lisbon immediately took such steps as erecting gallows to deter looters and salvaging building materials from debris.

Assessment questionnaires -- asking people how many shocks were felt, what kind of damage was caused -- were sent out. Some of the questions are the same as those used today.

Pombal is mostly remembered for a construction plan for Lisbon's Baixa neighbourhood which created a grid of level streets and uniform buildings using construction techniques designed to resist both earthquakes and fire.

Although recent disasters show man's science is still unable sometimes to cope with nature's ferocity, the Lisbon conference will show how far seismology has come since the 1755 quake.

"In Japan, almost all scientists have given up predicting future earthquakes," said Takashi Furumura, a seismologist at the University of Tokyo's Earthquake Research Institute.

He uses supercomputers to see how the ground shifts during quakes. Since many population centres are in sedimentary basins, his research can help cities detect how vulnerable they are.

The idea, Furumura said, is to anticipate ground movement before a seismic wave hits and oscillate buildings in the opposite direction so the motion cancels out.

"It's a dream," he said, "but who knew we could go to the moon?">