Geophysics fun – seismic acquisition (Credit: Miksha)

What does a geophysicist do? Almost everything that involves looking beneath the soil. Geophysicists study everything from buried tombs to the boundary between the Earth’s inner and outer core. They perform a sort of fancy X-ray magic which can include seismic, electromagnetic rays, magnetism, gravity – things that let us peek beneath the Earth’s skin without actually going there.

A friend of mine is a senior geophysicist at an environmental reclamation company. She uses her geophysics skills to supervise the remediation of spills and leaks, cleaning up other people’s earthly mistakes. A university colleague – someone whom I’d hired to work at my company – went on to use high-frequency radar to monitor the walls of potash mines, a kilometre below the surface. Another has been listening in our planet’s inner core’s low-frequency ringing. Still another looked for minerals in Costa Rica until his misadventures sent him packing. Quite a wide range, but none of my buddies has used geophysics to find coins and buttons on sandy beaches. Or tombs in central Europe.

Suleiman the Magnificent in 1530
(Portrait attributed to Renaissance artist Titian)

One tomb that had been lost to time, history, and the weathering of rocks and soil belonged to Suleiman the Magnificent (or Terrible, depending on which side of his border you were on). In the 16th century, Suleiman expanded the Ottoman Empire, strengthening control of the Levant, while capturing north Africa through Algeria, and Asia east to Persia. In 1564, he sent his navy to protect the sultanate of Sumatra, in Indonesia from Dutch interests. Suleiman conquered a huge chunk of central Europe, directing the troops himself. Twice he sieged Vienna and twice he conquered Budapest. He ruled an empire with 30 million citizens for 46 years – the longest reign of any Ottoman sultan. Under his rule, the empire reached its pinnacle in arts, science, and architecture – Suleiman rebuilt Jerusalem’s Old Wall and renovated the Kaaba in Mecca.

He was a complicated man. It’s alleged that he killed two of his sons because he didn’t think they’d be much good as heir to his throne. But he wrote endearing poetry under the pen name Lover. He ruthlessly crushed internal uprisings and rebellions, but usually treated his defeated foreign foes with mercy – when he captured Rhodes, the defeated Knights Hospitallers were given a civil send-off and provisions so they could sail to Malta (where they continued to fight him as the Knights of Malta).  Under his rule, subjects were free to practice their choice of faith, but preferential jobs were given to converts to Islam. His personal physician was a Jew exiled from Spain. Suleiman’s childhood friend, a Christian slave from northern Greece, converted and eventually became commander of all the empire’s armies. Suleiman’s wife was the daughter of a Ukrainian orthodox priest. After converting, she ruled alongside Suleiman. He was infatuated with her. Suleiman, a respectable poet, wrote of his wife Roxanna, “[You are] my wealth, my love, my moonlight. My most sincere friend, my confidant, my very existence, my one and only love.” It sounds even more convincing in Turkish.  But don’t take my word on any of this – it’s all in a soap opera, Magnificent Century, currently watched by 200 million people every week in 52 countries.

Monuments to Zrinski and Suleiman near Szigetvár

Geophysics played a role in the discovery of something that looks like the final resting place of Suleiman the Magnificent’s internal organs (the rest of his body was carried back to Istanbul). He died, at age 71, in his tent in southern Hungary while laying siege to a castle known as Szigetvár. The great sultan died but his men weren’t told, lest they quit fighting. The fortress, held by 2,300 Croatians and Hungarians, was no match against 150,000 Turkish soldiers. On the last day of battle, General Nikola Zrinski, a Croatian nobleman, died leading a suicide cavalry charge with his remaining 600 troops. About a dozen survived. They were spared and sent home by the Turks who said they greatly admired their adversaries’ spunk.

Counting a few of the 10,000 cannon balls launched against Szigetvár
during the 1566 siege. (Credit: Miksha)

According to legend, upon Suleiman’s death, the king/general/poet’s heart and liver were placed in a tomb on a hill above the castle. A Turkish town grew around the death shrine of Suleiman the Magnificent. Turbék had a dervish monastery, shops, and an inn for travelers who came to pay respects at the tomb over the next 150 years. But then the Ottoman Empire collapsed and the Turkish village on Hungarian soil was destroyed. Within a few generations, no sign of the former shrine or town remained. Instead, in 1919 a plaque was stuck on Saint Mary’s church, a kilometre away. The marker is still there, declaring Suleiman’s tomb is under the church, but there is no evidence that the church was actually built atop the sultan’s shrine.

Archaeologists, armed with geophysicists as tools, think they have found the neglected site. It’s in a vineyard on a knoll above the church. It is hidden under soil now, 450 years after Suleiman’s death. The newly discovered location seems to include a mausoleum, several small buildings, and possibly a dervish monastery. All of that may seem hard to miss, but Suleiman died in 1566 and everything was abandoned and wrecked when the Ottomans left the area in the 1680s. Remote sensing (satellite images) and geophysics have helped place the forgotten tomb.

Lead geographer Norbert Pap  from the University of Pecs began looking for the tomb by searching in the vineyard rather than at the church grounds after studying ancient maps and letters that indicated the approximate location of the long vanished village of Turbék. Aerial photographs helped, but the sleuthing is still remarkable. Would you have spotted the right place to dig from this photograph if I hadn’t placed the huge red circle on it?

Archaeological dig site in the search for Suleiman’s shrine.

Next came an archaeological trench which uncovered. . . something. It looks very promising. Shards of pottery with Arabic writing, some tiles, and the foundation of a building were found among the excavated grape vine roots. But looking at the soil, nothing resembles a lost town. It was time to call in the geophysicists.

Three types of geophysics were used to try to delineate the bounds of the buried ruins – magnetic, electrical, and radar. In October 2014, ground conductivity (EM, or electromagnetic) and vertical magnetic mapping techniques were attempted,  but the area had too much wire and reinforcing mesh (unrelated to the shrine) nearby to get consistent readings. Ferric material is obviously trouble for any methods using electrical conduction or magnetism. The EM system should have found the boundaries of disturbed subsoil by measurements of electric flow, but the interference from ground contamination wouldn’t allow clear results.

Typical GPR radargram.
Depth, shown to the left, in metres.

The geophysicists switched to ground-probing radar (GPR).  GPR blasts the soil with extremely high frequency signals which echo back to receivers. It’s similar to seismic exploration but GPR resolution is much finer, though it works only on shallow targets.

The GPR tests resulted in locating a large building with numerous small rooms, long buried below the vineyard. Archaeologists interpreted this as the dervish monastery. But the GPR’s prize discovery, at a depth of 100 to 125 cm (3 or 4 feet) below ground level, was a square building precisely aligned towards Mecca. They think it’s Suleiman’s shrine.

You may find this paper, written by Norbert Pap (et.al.) of the University of Pecs, an interesting read: Finding the Tomb of Suleiman the Magnificent in Szigetvár, Hungary: historical, geophysical, and archeological investigations.