sealPurdue Science and Health Briefs

November 1998

New study shakes up interest in earthquakes

WEST LAFAYETTE, Ind. -- A new look at the information on a 1971 California earthquake shows that several nearby faults were activated during the temblor, supporting evidence from more recent earthquakes that nearby faults may contribute to earthquake damage.

Xan Davidson, a graduate student working with Purdue University earthquake expert Arvid Johnson, found that surface fractures and other strains actually were caused by two faults other than the main fault, and contributed to the damage to streets, highways and buildings in the 1971 San Fernando earthquake.

Her study also found that because of blind faults, or faults that cannot be seen at the surface, the San Fernando fault zone is 11 miles long instead of 8 miles long, as it previously was assessed.

Results of the study, presented Oct. 29 at the annual meeting of the Geological Society of America in Toronto, suggest that estimates of potential earthquake damage should include areas surrounding nearby faults, as well as damage caused by the main rupture and ground shaking.

"Prior to 1989, scientists thought that all of the damage from an earthquake was the result of a single fault," Davidson says. "Since 1989, we have found evidence that more than one fault can be activated during an earthquake."

This is the first study that ties such an event to an earthquake prior to 1981, Davidson says.

"If, in fact, further research supports the notion of coactive faults during earthquakes, then predictions of earthquake damage must change focus from the main fault and the ground shaking caused by it, to include faults that might slip and move coactively with the main fault," she says.

Davidson says damage produced by blind faults and coactive faults was not recognized until studies of the 1989 Loma Prieta, 1992 Landers and 1994 Northridge earthquakes. Those studies were carried out by Johnson and Bob Fleming of the U.S. Geological Survey.

To see if nearby faults were activated during the 1971 San Fernando earthquake, Davidson used survey data, from 1972 and earlier, to determine damage to streets, highways, office buildings and dwellings in areas the size of city blocks.

Her study showed that patterns of energy release -- illustrated by ground ruptures and other damage -- indicate that two nearby faults were activated during the earthquake. "Damage in these areas could not be attributed to the ground shaking caused by the main fault," she says.

Davidson and Johnson now are working with others to study how coactive faults are activated during an earthquake, and how fault lines may be interconnected.

CONTACTS: Davidson, (765) 494-0250; or Johnson, (765) 494-0250; e-mail,

Thinkers enjoy added influence

WEST LAFAYETTE, Ind. -- Charm, looks and personality can take you only so far. If you want to influence people -- try using your brain.

"In studying influential people, researchers are seeing that persons who enjoy thinking have added impact," says Duane Wegener, associate professor of psychological sciences at Purdue University. These thinkers are described as having a "need for cognition," or NC.

People high in NC would prefer chess to checkers or reading a book to watching TV. Wegener says these people have a desire to use their brains, which results in their forming strong opinions. "One of the reasons they are influential is the strength of the attitudes they hold," he says.

To see how it works, Wegener and two colleagues studied 74 students at two universities who participated in an exercise to study how jurors make decisions. The students were divided into small groups and then later paired off. Before the exercise, all the participants were rated on their NC. Persons high in NC were paired with students lower in NC.

The participants read summaries of a civil case and legal analyses. Members of each pair unknowingly received differing analyses -- one supporting the defense, the other the prosecution. After reading the material, the participants were asked to discuss the case with their partner and render a joint verdict.

The prediscussion views of those who like to think prevailed most often. "Fewer high-NC participants changed their minds as a result of the discussion than did their lower-NC partners," Wegener says. Overall, the lower NCs were twice as likely to accept the views of higher NCs.

He says the people who liked to think were perceived by their partners as generating more valid arguments and as being effective persuaders. "It could be that the thinkers had better-prepared arguments based on greater scrutiny of the trial evidence," Wegener says.

The NC results might also explain past research showing that group decisions are influenced by variables such as a person's level of education and occupation. "People who are more educated, and those in certain high-status jobs, also tend to be higher in NC," Wegener says.

Wegener's study was conducted with Donna Shestowsky of Yale University and Leandre R. Fabrigar of Queen's University. It was reported in May in the Journal of Personality and Social Psychology.

CONTACT: Wegener, (765) 494-9554; e-mail,

Students with 'right stuff' can get right starting salary

WEST LAFAYETTE, Ind. -- Studying to become an astronautical engineer may not necessarily launch students into space, but it may very well land them a lucrative career.

"Astronautical engineering isn't just about being groomed to become an astronaut, although Purdue is proud to have many of its graduates go on to 'clock-in' among the stars, " says Kathleen Howell, professor of aeronautics and astronautics at Purdue University. "Our program is designed to make students employable in every aspect of space research, development and exploration."

According to industry experts, one area in particular is booming -- satellites. Pagers, cellular phones, direct TV and syndicated radio all depend on satellites to do their jobs. And before anyone can get beeped, buzzed or zoned-out in front of the tube, these satellites have to be built and launched into orbit. Industry reports indicate that more than 1,500 satellites -- mainly commercial -- will be launched in the next 10 years. Getting them built and launched is where astronautical engineers come in.

"And demand far exceeds supply," says Stephen Heister, Purdue associate professor of aeronautics and astronautics. "This year alone, our office at Purdue received inquires for more than 400 jobs, and we know these companies could only find enough astronautical engineering graduates to fill half the positions. The 43 students graduating from the program in May received, on average, two to three job offers apiece."

The average starting salary for those who accepted employment was $41,388, according to Purdue's Center for Career Opportunities.

CONTACTS: Howell, (765) 494-5786; Heister, (765) 494-5126

Check home air quality for dangerous gas

WEST LAFAYETTE, Ind. -- As the cold weather sets in, you welcome the warmth of your furnace or gas-log fireplace, but they may also bring a silent, invisible killer into your home.

Carbon monoxide, a byproduct of improper combustion of some fuels, has been associated with the death of more than 200 people in this country each year. The poisonous gas also sends nearly 10,000 people to hospital emergency rooms annually for treatment.

Household appliances that burn natural or LP gas, kerosene, oil, coal, or wood can produce carbon monoxide as a byproduct, according to Cathy Burwell, Purdue University Extension Service specialist in water quality and environment in the School of Consumer and Family Sciences. The odorless, colorless gas can be produced by furnaces, stoves, fireplaces, clothes dryers and some space heaters.

"Carbon monoxide poisoning is especially hazardous, because its initial symptoms can be likened to those of the flu," Burwell says. "Many people have no idea that their headaches, fatigue and nausea may be a result of carbon monoxide poisoning."

Other symptoms associated with carbon monoxide poisoning include shortness of breath and dizziness. She says exposure to high levels of carbon monoxide can cause death.

Burwell suggests that a qualified technician inspect the heating equipment, including the unit, chimney, flues and vents, each year. Part of the inspection should include a check for adequate ventilation to appliances. "A supply of fresh air is important so that pollutants from the combustion process are carried away," she says.

This is not a do-it-yourself job, Burwell says. She says air quality inspections can be done by certified heating and air conditioning technicians as well as by some gas utility inspectors.

As an added protection throughout the year, homeowners may want to invest in a carbon monoxide detector. These detectors, similar to smoke detectors, make a loud noise when carbon monoxide is present.

She says carbon monoxide detectors should meet current Underwriters Laboratories standards and are available at most hardware stores. Prices range from $20 to $50. The higher-priced models include a readout that displays the level of gas present.

CONTACT: Burwell, (765) 494-8252; e-mail,

Compiled by Amanda Siegfried, (765) 494-4709; e-mail,

Purdue News Service: (765) 494-2096; e-mail,

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