Most Missourians don't give much thought to earthquakes. After all, residents here are more likely to encounter tornados than their natural disaster cousin, quakes. But, news of three recent, massive ground-splitters thousands of miles away first in Haiti, then in Chile and now in Taiwan, have some Missourians wondering about the status of a major seismic fault that cuts through the state's southern tip.

There's a little bulls eye in the area of the boot heel," explained Robert Herrmann, professor of geo-physics at St. Louis University, where he conducts research at The Earthquake Study Center. The fault spans southeastern Missouri, northeastern Arkansas, southern Illinois and western Kentucky and Tennessee.

An earthquake Tuesday afternoon near Sikeston, Mo., which is located within the New Madrid Seismic Zone, simply added to speculation about the possibility of a larger quake there. The quake, about 150 miles from the epicenter, registered 3.7 magnitude while the quakes in Haiti and Chile measured 7.0 and 8.8, respectively. Another earthquake, which measured 6.4, hit Thursday in Taiwan. That means recent earthquakes struck Jan. 12, then six weeks later on Feb. 27 and less than one week later, March 4.

In comparison, the Missouri quake was much less severe. "It's just on the threshold of being noticeable," Herrmann explained. There was just a slight jostling of the ground."

Despite the mild nature of the Missouri quake, officials with the U.S. Geological Survey, who analyze and track the location and magnitude of area earthquakes, reported that nearly 200 people who felt the quake responded to the "Did You Feel It?" website." The New Madrid fault most typically registers quakes in the magnitude range of 1.0 to 2.0. Geological Survey officials use the postings to forecast the results, said Rob Williams, a geo-physicist with the U.S. Geological Survey in Golden, Colorado.

He said people in earthquake-prone areas react very differently to plate movement than those who live in more uncommon quake sites, such as Missouri. For instance, those who live near California's San Andreas Fault, are so accustomed to quakes, they readily identify them, and can usually estimate the magnitude. By contrast, Missourians often notify U.S. Geological Survey officials and ask if there was a quake and, if so, what was the magnitude?

The recent quakes in Haiti, Chile, and now Taiwan, were impossible to ignore. Because most homes in Haiti are constructed of hurricane-proof concrete and cinder-block, the buildings readily crumbled, destroying many homes, schools and other buildings and leaving an estimated 230,000 to 270,000 dead. The death toll is attributed to falling buildings that literally collapsed on top of those inside. The Chilean quake was much less destructive due to the higher-quality, more stable building material and construction. Officials there estimate the quake killed about 723. Death toll estimates in Taiwan were not yet available at press time.

While residents of southern Missouri and emergency preparedness officials were pleased that Tuesday's quake was mild, those who study them at the Earthquake Study Center in St. Louis, glean much more from those that register higher magnitude. Officials monitor about 30 seismographs placed in the fault area, which record the earth's movements. These seismographs are so sensitive that they monitor even minor earth movements, such as when the earth shifts due to wind, Herrmann said. For instance, in St. Louis, the equipment recorded a ground shifting of 1/4 inch due to the impact of the earthquake in Haiti, thousands of miles away.

"Our instruments are such that if there's an earthquake anywhere, we're going to pick it up," Herrmann said. But scientists learn more from larger quakes than their smaller counterparts.

"My only regret is if it had been a little more sizeable, I could have done a better study," Herrmann said. Of course, smaller quakes occur much more frequently than those of larger magnitude, he said.

The last time quakes of larger magnitude struck the New Madrid Seismic Zone was in Dec., 1811 and February, 1812, before technology was sophisticated and widespread enough to accurately record such data. While seismographs were first invented during the late 1800s, they weren't widely used and weren't digitally adapted until much later, sometime in the 1970s, Williams said. Therefore, scientists have learned more about the 1812 earthquake from modern-day studies of soil in the area He said such samples offer evidence of the significant quake, along with others of higher magnitude in 900 and 1450 AD.

The largest recent quake along the fault was one measuring 5.3 struck along the fault in southeastern Illinois in 2008, only 100 miles from St. Louis, Herrmann said. That quake was significant enough to cause damage to some buildings, especially old, brick structures, such as chimneys, which have no modern steel reinforcement to offer stability. Such old brick work can become cracked, or, in some cases, can cause walls to crumble and fall.

In fact, Herrmann explained that unstable structures are one reason studies, such as those conducted by the Earthquake Center, are so important. He said the seismographs provide data that notify area engineers of possible severe damage to buildings and bridges. Such damage could cause instability, leading to serious injury and, perhaps, death. In addition, such data can allow for quick response by emergency response agencies in case of a major quake. Another benefit of seismographs is the overall detailed information they offer.

"We're really interested in, 'why do we have earthquakes in the first place?' " Herrmann asked, a question scientists are still trying to answer.

While geo-physicists and other such scientists spend a lot of time analyzing earthquake data, they agree on one simple fact, Herrmann said. There's no way to predict when earthquakes will strike, or their magnitude. The recent activity in Haiti, where an estimated 230,000 to 270,000 have died, and Chile, where the death toll is about 723, and, in Taiwan, in no way signal the likelihood of large earthquakes anywhere else.

"Earthquakes today are no more frequent than they ever were," Herrmann said. "They pop off at the same rate as always."

Although unpredictable, those who study plate movement can calculate their approximate timing based on past activity. For instance, scientists studying the New Madrid fault estimate there's a 25 to 40 percent chance of a magnitude 6.0 or larger, or a 7 to 10 percent chance of a larger, 7.0 to 8.0, all in the next 50 years.

Because the affects of earthquakes increase at a very high rate with each successive point magnitude, from 5.0 to 6.0, 6.0 to 7.0 or 7.0 to 8.0, "...a 6.0 (along the New Madrid fault) would be pretty significant," Williams said.

However, Herrmann offered this warning. "We know we had a very large earthquake here 200 years ago," he said. "It would be prudent to consider that (another quake) a likelihood. Future earthquakes could be anywhere."