A Damper on Earthquakes

PROFESSOR CINNA LOMINITZ of the National University of Mexico has lived through some of most deadly earthquakes in the Americas. When he was 14, he survived Chile’s 1939 earthquake that measured a magnitude of 8.3 and killed 28,000 people.

Years later he felt the effects of Chile’s 1960 earthquake that measured a magnitude of 9.1. He has never forgotten the cries of the wounded after the 1985 earthquake in Mexico City that destroyed 400 buildings and killed 10,000 people. Perhaps that is why he has devoted his professional life to understanding earthquakes and how to survive them.

One question he set out to answer is why do some powerful earthquakes do little damage and weaker ones do great damage? For example, the 2003 Colima, Mexico, earthquake had a magnitude of 7.4 but killed only 18 people. The difference, according to Lomnitz, might be a matter of mud.

Significant parts of Mexico City are built upon ancient mud flats that have a natural “pitch” of one cycle every 2.5 seconds. All objects vibrate at a specific frequency, and unfortunately Mexico City’s mud vibrates at the same frequency as certain earthquake waves.

The danger increases in buildings that are 10 to 15 stories tall because they, too, have a 2.5 second period.

“It’s like a tuning fork,” Lomnitz says. “They start vibrating with the earthquake. Since they lack damping, they don’t just move once. They move worse and worse as the earthquake proceeds.” Eventually the buildings sway out of control and collapse. “Something like that can happen in every earthquake,” he explains.

“However, in Mexico City it just specifically attacks buildings with that height. For example, in the downtown area you can find hundreds of old churches. Nothing happens to them. They’re not tall enough. This is true for all of the old colonial buildings.”

Major metropolitan areas in other parts of the world — such as the San Francisco Bay Area and the waterfront district of the Japanese city of Kobe — also have been built on mud flats and lakebeds. Both of those cities suffered devastating earthquakes in the past two decades.

Professor Lomnitz suggests that buildings, like cars, be equipped with dampers to make them more earthquake-resistant.

“These dampers work exactly the way the shock absorbers do in the car,” he explains. He believes that not only should dampers be included in new buildings, but they should also be added to already-existing buildings.

According to Lomnitz, the technology is available, the process is relatively inexpensive, and even though dampers do add to the construction cost, they add to the value of the building because they help save lives.

torre
El Torre Mayor, Mexico City

Lomnitz points out that although a solution exists, dampers are not standard equipment in structures and their use is not yet widely recommended in building codes.

Mexico City now has one building that is equipped with dampers. At 55 stories high, the Torre Mayor is the tallest building in Latin America. It was built in 2003 and includes 96 dampers.

To educate others about the value of damping on soft ground, Lomnitz strives to be heard in the scientific community. A professor of seismology at the Institute of Geophysics, National University of Mexico, he is also a member of the Mexican Academy of Sciences, a chairman of the Committee of Earth Sciences in the National Research Council of Mexico, and a participant in UNESCO emergency field teams.

“My hope is that much more will be done about this peculiar problem to enable us to do away with earthquake risk on soft ground altogether.”


Published in Americas magazine,  July-August 2004, by Chris Hardman

Purses from Plastic

THE UBIQUITOUS PLASTIC grocery bag—used for lunches, garbage cans, and groceries—is one of the most prolific sources of pollution in modern-day society. Scientists estimate that worldwide people use 500 trillion plastic bags each year. In the Americas alone, the United States reports using 380 billion plastic bags a year. Cheap to buy and easy to store, the plastic bag has become the favorite of grocery stores who no longer ask, “Paper or plastic?”

Lack of recycling programs and improper disposal of the bags create a waste nightmare and environmental hazards that are too complex to track. Non biodegradable plastic bags travel on the wind polluting our oceans and forests or take up permanent residence in our already overcrowded landfills.

Since 2006 an innovative program that started in Costa Rica is using those bags in a most environmentally friendly way. Women living in small villages on the Caribbean Coast convert the plastic bags into thread and weave attractive and colorful purses with them.

Weaving for Nature is run by WIDECAST, a conservation organization that protects sea turtles in the Caribbean and its surroundings. The program solves several problems at once. The bags are re-used, eliminating the need for disposal, and the business gives people an environmentally friendly income source.

The program is organized to promote fair trade standards with an environmental mission. The weaver receives 75% of the profit and the rest goes toward sea turtle conservation efforts. The weavers, mostly housewives in small villages, work under fair and relaxed conditions and are compensated for all stages of production from collecting and washing the bags through the finished product.

According to Didiher Chacon-Chaverri, WIDECAST Country Coordinator in Costa Rica, weavers produce about 3 purses a week that means they can earn $180 a month to supplement their family’s main income.

To date the project has employed more than 50 women in villages on the coast of Costa Rica, Panama and Nicaragua. In 2008 the sale of bags, coin purses, plastic figures and Christmas Tree ornaments generated $75,000 in income for the four coastal communities.

The environmental benefits of this program are far-reaching. Along the Caribbean coast of Costa Rica and other countries, the plastic bag is a deadly enemy of marine habitats.

Because many of these bags are thrown on the ground or tossed into rivers, they often end up in the sea where they suffocate coral and kill sea turtles. For the hapless sea turtle gliding through the ocean, a plastic bag looks just like its favorite food, the jellyfish. The turtle gobbles up the bag and either chokes on the plastic or feels full and stops looking for real food.

Unfortunately plastic waste of any kind affects the entire marine environment. Because plastic bags are made of polyethylene, they are not biodegradable, and even if the bags are broken into smaller pieces, their tiny particles invade all levels of the food chain causing disease and sometimes death for marine life.

The Dolphin Research Center in Florida estimates that 100,000 marine mammals die each year from eating plastic bags.

WIDECAST estimates that each purse made is removing approximately 70 plastic bags from the environment for a total of 12,000 plastic bags a month. The bags are sold throughout Costa Rica in tourist areas and gift shops and online through http://www.inbio.ac.cr.

They range in color and size and come in various styles including beach bags, calabash bags, messenger bags, water bottle cases, and coin purses. For more information about the project, visit latinamericanseaturtles.org.


Published in Americas magazine, September-October 2009, by Chris Hardman

 

March of the Desert Penguins

THE LIFE OF THE arctic penguin has been well represented in films and documentaries in recent years as 4-foot tall emperor penguins have marched across our movie screens. Now new research shows that the ancestors of these modern-day giants, were larger, sturdier and lived in the deserts of Peru during one of the warmest periods on Earth—some 36 to 42 million years ago. A team of scientists from the U.S., Peru, and Argentina has found two new species of penguins that are challenging accepted theories of penguin evolution and migration.

Peruvian paleontologist Mario Urbina-Schmitt of the Museo de Historia Natural de San Marcos in Lima, who has logged more than 20 years of fieldwork in Peru, helped to locate the fossils. Unexplored areas can lead to exciting discoveries like the new species of giant penguin named Icadyptes salasi, the third largest penguin known to science. With a beak that measures more than two times the length of its skull, Icadyptes had the longest beak of any penguin in the world. A true giant, this magnificent bird stood about 5 feet tall, was sturdy in constitution and waddled about the deserts of Peru about 36 million years ago. The researchers also found a second, much older fossil from a 42-million-year-old deposit. The earlier penguin, Perudyptes devriesi, was three feet tall, which is comparable in size to today’s second largest living penguin, the King Penguin.

Excavations in Peru also produced the first complete sample of a giant penguin skull. “We really only had ideas about what the skulls of these animals looked like,” says North Carolina State University Assistant Professor Julia Clarke, one of the lead scientists who analyzed the remains. “[The skull] is quite different from any living penguin,” she explains. With an actual skull to examine, scientists can more accurately determine what some of the earliest penguins looked like. Although both of the new species had longer and more pointed beaks than today’s birds, the giant penguin had a super-sized beak that is longer than any beak found in any living or extinct penguin. The super-sized beak had a sharp, spear-like point at the end that scientists suggest was used as a weapon to catch fish. To support this massive beak, the penguin’s neck was thick and muscular.

The age of these new fossils pushes back the date of penguin migration from southern latitudes to low latitudes millions of years earlier than previous data had indicated.  Scientists have long believed that penguins migrated to northern South America during a cold era, between four and eight million years ago, but these new fossils hail from a warm period more than 30 million years earlier. Penguin researchers were quite surprised to find penguins living in the tropics during a time period when the earth was even warmer than it is today. “We tend to think of penguins as being cold-adapted species, even the small penguins in equatorial regions today,” says Clarke, “but the new fossils date back to one of the warmest periods in the last 65 million years of Earth’s history. The evidence indicates that penguins reached low latitude regions more than 30 million years prior to our previous estimates.”

Clarke warns that although penguins might have started out living in warm climates, today’s penguins are cold adapted and sensitive to climate change. “These Peruvian species are early branches off the penguin family tree, that are comparatively distant cousins of living penguins,” she explains. “The data from these new fossil species cannot be used to argue that warming wouldn’t negatively impact living penguins.”


Published in Americas magazine by Chris Hardman

 

Radio-Tagged Tarantulas

THE THOUGHT of studying tarantulas up close causes most people to shudder as images of gigantic, hairy monsters flood their imagination.  But a more accurate picture, according to Steven B. Reichling of the Memphis Zoo, is that of a fascinating animal providing an invaluable service to conservation research. Reichling and veterinarian Chris Tabaka have radio tagged 75 individuals of two common tarantula species to document the rate and result of deforestation at the Lamanai Archaeological Reserve in northern Belize.

Tarantulas make effective bio-indicators because they can live to be 20 years old, they are identifiable, and they stay in one area. By monitoring tarantula survivor rates, Reichling will be able to document the impact of agricultural trends in Belize.

Historically, farmers planted crops on small plots of land for a few years and then cleared a new area. This “slash-and-burn” farming allowed the land to rest and recover. But modern farming techniques create large clearings that are left fallow briefly or not at all. Large-scale farms cultivate the land continually, and once all the nutrients in the soil are used up, the farm becomes cattle pasture. The behavior of Reichling’s two study subjects, the Lamanai tarantula—a resident of open fields—and the redrump tarantula—a dense forest dweller—will provide insight into how other species of flora and fauna are affected as well.

The first challenge the researchers faced was how to identify an animal that sheds its exoskeleton on a regular basis. They decided to use some kind of internal tag. Because tarantulas have an open circulatory system and no clotting ability, Reichling says, “It’s a lot like trying to insert a grain of rice inside a water balloon.” Tabaka and Reichling developed a technique to surgically implant miniature radio transponders into the spider’s abdomen without harming the animal. These long-lived archachnids will generate valuable scientific data for years to come.


Published in Wildlife Conservation by Chris Hardman

Fragments in the Forest

AS MORE and more of the tropical rainforest is clear-cut for ranching or development, isolated forest fragments are left where large tracts of continuous forest once stood. Conservationists warn that forest fragments can’t sustain healthy animal populations like continuous forests do. Recent research by University of California at Davis scientist Emilio Bruna shows that plants, too, need continuous forests to survive.

In a rainforest near Manaus, Brazil, Bruna compared the progress of seeds from a common type of Heliconia he planted in a continuous forest to seeds he planted in a forest fragment. He checked the plant’s status each month for a year.

The results were dramatic. The seeds in the forest fragment were 3-7 times less likely to germinate than those in the continuous forest. “In terms of population growth, 7% could be a really big difference,” Bruna says. “Just think of a bank account earning 7% less interest a year.”

Bruna attributes the difference to edge effects —an unnatural environment created by clear cutting part of a forest. Edges put forest seeds in an environment with higher temperatures, increased humidity, and more sunlight.

Typically, a rainforest seed would land on the bottom of the rainforest floor, a dark and cool environment protected from the sun. Seeds that land in edges are exposed to intense heat, more sunlight, and increased wind. Some seeds die or simply never germinate—the wind and heat dries them out.

Another obstacle comes from trees at the edge of the forest, who are stressed and tend to lose more leaves. The excess leaves cover the seeds causing them to mold or to receive no sunlight at all.

“If the effects were felt in plants that were common, this might suggest rarer plants are at an even greater risk,” Bruna says.

Bruna’s research is part of the Biological Dynamics of Forest Fragments Project, a partnership between Brazil’s National Institute for Research in the Amazon (INPA) and the US-based Smithsonian Institution.

This unique project began 20 years ago when ranchers began to cut down the rainforest around Manuas, Brazil. Seeing a scientific opportunity, INPA scientists asked the ranchers to leave isolated strips of forest around their land. Studies both before and after isolation have resulted in a wealth of information about the effects of forest fragmentation on plants, birds, insects, and animals.

The results of Bruna’s research show that continuous forests are just as important for plant reproduction as they are for animals.

“Fragmentation can influence plant reproduction in unexpected ways.  It suggests that even if pollination and seed dispersal—two interactions thought to be very susceptible to the effects of fragmentation because they usually depend on animals—are successful, environmental conditions may cause reproduction to fail,” he explains.

“If this goes on for long enough, plants in patches of rainforest may find their population sizes dwindling away, perhaps ultimately leading to extinction.”


Published in Americas magazine, May 2000, by Chris Hardman