Science moves in curious ways, particularly in this multidisciplinary age. Consider the part played by Museum astronomer Steven Soter in the recent discovery of what may be classical Helike, on the southern shores of Greece’s Gulf of Corinth.

Helike, a city mentioned by Homer in the Iliad, has been one of the last major puzzles of classical archaeology in Greece. In 1968 Spyridon Marinatos, director-general of antiquities for the Greek ministry of culture who had searched unsuccessfully for the city, called attention to what were then three important problems in Greek archaeology: the sites of ancient Thera, ancient Thebes, and ancient Helike. He had just found Thera, and ancient Thebes turned up beneath modern Thebes. Only Helike remained.

Steven Soter and Dora Katsonopoulou by a Hellenistic wall excavated at Helike. Photo by Steven Soter

Soter, who also works as a geoarchaeologist (a scientist who uses geology to investigate archaeological sites) is codirector, with Greek archaeologist Dora Katsonopoulou, of the Helike Project, which sent a dozen scientists and students into the field this past August and September. On a coastal plain of the northern Peloponnese, near modern Eliki, the team unearthed what is almost certain evidence of ancient Helike, which sank beneath the gulf during a major earthquake in 373 B.C. (the discovery is to be announced near the site on October 7, as we go to press). In the course of digging four trenches, the team turned up, in addition to earlier Archaic material and later Hellenistic material, a layer containing classical pottery shards together with marine shells and what may be the remains of seaweed—possible evidence that Helike’s ruins were once beneath the sea. All this is awaiting further analysis, as is a corroded bronze coin discovered on September 12, the last day of this year’s excavations.

How did a Museum astronomer get mixed up with such subterranean doings? He was studying methods of predicting earthquakes. And how did he get mixed up with earthquake prediction, normally the domain of geologists with seismometers and strain gauges?

How did a Museum astronomer get mixed up with such subterranean doings?

Soter, a soft-spoken staff scientist in the Museum’s Division of Physical Sciences-Astrophysics, got his doctorate in astronomy from Cornell University in 1971 and for fifteen years was on the staff of Cornell’s Center for Radiophysics and Space Research. He worked as a research associate at the center with Thomas Gold, an astrophysicist who thinks that earthquakes are triggered by the release of gases that were incorporated into Earth during its formation and are now under enormous pressure from the overlying rock. Forcing their way up through cracks in the upper mantle, these gases can counteract the pressure that clamps Earth’s tectonic plates together. The high-pressure gas reduces the friction across a fault, allowing the shearing forces in the rock to shift the plates sideways, sometimes catastrophically. From Gold’s standpoint, it is a sudden decrease in fault strength, not a gradual increase in rock stress, that triggers an earthquake.

In the late 1970s, Gold asked Soter to study earthquake literature, with a particular eye out for precursor events that might confirm his maverick ideas. Soter found many phenomena of this kind that might be related to "outgassing," including, for example, numerous anecdotal reports of odd animal behavior before earthquakes. Many animals are far more sensitive to smell and other physical changes than are humans, and some of their strange behavior might be a reaction to the effects of venting gas as it permeates the soil. The earliest account of such odd animal behavior comes from the Greek rhetorician Claudius Aelianius, or Aelian, writing in the second century A.D. and drawing on sources now lost. He noted that for five days before the earthquake in 373 B.C. at Helike, "all the mice and martens and snakes and centipedes and beetles and every other creature of that kind in the town left in a body by the road that leads [south] to Keryneia." According to Aelian, the people were amazed and did not know what this meant. Then the earthquake struck, and the city was submerged by the sea. Spartan warships anchored in the harbor disappeared. All that showed of Helike above water, according to Pausanias, a Greek geographer and traveler writing in the same century as Aelian, were the tops of trees from a sacred grove dedicated to Poseidon. For centuries, fishermen snagged their nets on the ruins.

In the course of his research, Soter became fascinated with the possibility of finding Helike. The coast of the Gulf of Corinth and the alluvial plain, where Helike once stood, are located in one of the most seismically active areas of Greece, at the foot of the mountains of Achaea in the northwest Peloponnese. While the mountains here are moving upward, the coastal plain is slipping downward along the roughly parallel Helike and Aigion fault lines, which slice the area as if it were a loaf of bread. Quakes occurred along these faults in 1748, 1817, 1861, 1888, and 1995. All in all, it is a good place to look for precursors.

To Soter, these accounts may be evidence of the release of gas before and during earthquakes.

Because of its sudden plunge, the ancient city could have been as well preserved as a shipwreck, but researchers’ efforts to locate Helike had until now proved elusive. At the urging of Spyridon Marinatos, Harold Edgerton, inventor of sonar that is capable of subbottom penetration, looked for the city in the 1960s and did not find it. Suspecting that Helike, after centuries of sedimentation and uplift, might lie buried beneath the inland alluvium, Soter and Dora Katsonopoulou, whom Soter had met at Cornell, began in 1991 to sink boreholes into the coastal plain. They found what appear to be buildings from the Roman period overlying material from the classical period as well as the Bronze Age and the Neolithic period.

In June of 1995, while Soter and Katsonopoulou were digging up bits of ancient pottery and brick, another earthquake—of magnitude 6.2—struck the area. Soter collected a dozen accounts of strange events preceding this temblor. Minutes before the earthquake struck at 3:15 a.m., a geophysicist from the Helike Project, working in a hotel room near the site, heard the sound of wind growing louder than any storm.

This past summer, the Helike Project unearthed what may be one of the ancient city’s roads. Photo by Steven Soter

But when he went outside to investigate, the trees and air were completely still. Some people told of subterranean boomings before the quake; others of strange lights in the sky, red glows, and fireballs. Local fishermen reported the appearance of large numbers of octopuses. A man driving his car near Eliki the night before the quake found dozens of dead mice on the road, all run over by cars while apparently heading south toward the mountains. A dog chained outside a house howled unaccountably every night for a week until the quake struck, then broke his chain and was not seen again after the ground nearby erupted, spewing sand and warm water high into the air. (In the same area during the 1861 earthquake, a man was killed by a similar explosive venting. A painting made afterward shows sand volcanos: mounds of sand topped with vents.)

To Soter, these accounts may be evidence of the release of gas before and during earthquakes. On windless days gas can vent with the sound of a gale; if the gas is flammable, it can ignite into fireballs from the friction of dust particles entrained with it; or it can insinuate itself into the porous soil, driving ground-dwellers out of their burrows.

Luckily, Soter was able to add to these anecdotal data actual instrumental observation of a precursor event. By chance, a few days before a 1993 quake in the nearby Bay of Patras, oceanographers at the University of Patras had been using a thermal probe to record the water temperature near the bottom, some sixty-five feet below the surface. When they looked at their data after the quake, they found that the temperature, which normally hovered at about 63°F, had shot up to 73° in the hours before the quake. Afterward, the temperature had returned to normal. Ten days later, using side-scan sonar, the oceanographers discovered a field of craters in the seafloor surrounding the thermal probe, some hundreds of feet across and still venting gas bubbles. Such pits could be the undersea counterparts of sand volcanos on land.

Maybe people will learn to pay attention to the sound of wind on a calm day, the howling of dogs, and the appearance of octopuses and will head for the hills—just as the mice did at modern Eliki and ancient Helike alike.

Henry S. F. Cooper Jr., a former staff writer for the New Yorker, has been visiting the Museum since he was four years old, when his father sat him in a cavity of the Willamette Meteorite.

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