Seismology is a branch of earth science which is concerned with earthquakes and other activity that occurs beneath the planet’s surface. The scientists who work in this field are called seismologists. Usually these professionals hold advanced degrees. They monitor earthquake activity, attempt to predict it and work with many other geologic and scientific fields in such diverse activities as searching for oil and natural gas reserves and mining.
The word, “seismic”, comes from the Greek word for earthquake and the word “logo” comes from the Greek word for knowledge. Seismology is the study of earthquakes and seismologists are the scientists who study them. While ancient people created myths to explain earthquakes, the first European scientific study of earthquakes began after a devastating earthquake hit Lisbon, Portugal, in 1755. As many as 70,000 people were killed in that earthquake and by the tsunami that followed.
Following the Lisbon earthquake scientists began recording the time, location, and specific effects of earthquakes. The earliest observers included the Englishman John Mitchell, and Elie Bertrand, from Switzerland. By 1820, earthquakes were associated with changes in the earth’s surface because of the writings of Maria Graham about changes in the coast of Chile. Robert Mallet, of Ireland, is credited with figuring out measure the depth at which earthquakes occur in the late 1800s. The understanding that plate motion along faults is a cause of earthquakes was the conclusion of the American Grove Karl Gilbert in the early twentieth century. His work inspired another American, his contemporary, Harry Fielding Reid, who described how earthquakes allow for pent-up stresses in the crust to be released.
Seismologists rely on an instrument called a seismograph that measures the frequency and amplitude of the waveforms generated by earthquakes. A primitive seismograph was invented as early in the second century AD in China. Modern seismographs can measure waves generated around the earth. The first electromagnetic seismograph was invented by Luigi Palmieri in the late nineteenth century. One of his seismographs was installed near Mount Vesuvius, the volcano that destroyed Pompeii in 70 A.D. By the early 1900s researchers at the University of Tokyo built a seismograph with much improved the sensitivity. The data gathered by the increasingly accurate seismographs measure the seismic waves produced by earthquakes, volcanoes, explosions and events that you might not think of as having a seismic signature, such as avalanches and landslides. Using the data from these instruments, seismologists look for patterns from which they can draw conclusions and make predictions.
Seismologists provide important expertise for many commercial and national purposes. Ground motion specialists consult with architects and engineers who are building and planning bridges and buildings so that they will be able to withstand a major earthquake. They also advise disaster relief personnel about where an earthquake might do the most damage so that they can plan ahead in case one happens. The petroleum industry hires seismologists to locate new oil deposits using the same technology that helps them to study the structure of the inner earth. Government seismologists monitor the earth to learn when other countries are testing new weapons by detonating them deep underground. The US Geological Survey also hires seismologists to monitor and interpret seismic activity.
Seikei Sekiya of Japan was the first person to become a professor of seismology. Another Japanese seismologist derived the formulas to show the rates of an earthquake’s aftershocks. This kind of research requires highly trained scientists with advanced degrees following an undergraduate degree in geology, computer science, geophysics, math or physics. If you are interested in this field, you can watch a real-time seismic monitor online that shows where earthquakes are happening.