Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unearthing clues of catastrophic earthquakes

18.04.2008
An inviting tale of destruction

The destruction and disappearance of ancient cultures mark the history of human civilization, making for fascinating stories and cautionary tales. The longevity of today’s societies may depend upon separating fact from fiction, and archeologists and seismologists are figuring out how to join forces to do just that with respect to ancient earthquakes, as detailed in new studies presented at the international conference of the Seismological Society of America.

"It's an idea whose time has come, " said Robert Kovach, professor of geophysics at Stanford University and a leading proponent that seismology needs to be included in any framework for understanding what happened to past civilizations. Very large earthquakes may have recurrence rates that exceed 500 years, making it very difficult to assign potential hazard estimates.

Archaeoseismology, a young scientific discipline that studies past earthquakes in the archaeological record, allows scientists to broaden the time window to detect these rare seismic catastrophic events. But archaeological evidence for past earthquakes raises a lot of reservations from seismologists, some of them strongly questioning whether man-made structures can be used as earthquake indicators at all.

Controversy stems from what is seen by some seismologists as haphazard blame placed on earthquakes by archaeologists for inexplicable phenomena on an archaeological site, adding drama to the site’s history. “We need to be wary of circular reasoning” said Tina Niemi, a geologist at the University of Missouri-Kansas City, who noted the temptation to assign evidence to match a preconceived notion that an earthquake may have caused damage.

“We are indeed at a turning point with respect to archaeoseismology -- either earthquake evidence in archaeological sites remains in a world of conjecture and drama or a more objective and quantitative approach gets the upper hand,” said Manuel Sintubin, professor of geodynamics at Katholieke Universiteit Leuven in Belgium.

Earlier this month UNESCO awarded a five-year grant to Sintubin and his colleagues Niemi; Iain Stewart, geologist at University of Plymouth in the United Kingdom; and Erhan Altunel, geologist at the Eskisehir Osmangazi University in Turkey, to support archaeoseismology by broadening the field’s primary focus from the Near East to include the Far East.

“The importance of this effort is to create a long-term, worldwide platform for a broad multidisciplinary discussion on archaeoseismology. Our final objective is to assure that archaeoseismology will be considered as a legitimate and complementary source of seismic-hazard information.”

There is still much to be known about ancient earthquakes. The instrumental record for seismology is short, going back 100 years. The historical seismology record is a much longer, including written documentation such as news accounts and diaries, which vary widely by culture and region. The archeoseismic record serves as the bridge between historical accounts and the paleoseismic record of Earth’s history.

“It's important to society to understand the risks posed by earthquakes with longer repeating cycles,” said Kovach. "Unless the world was drastically different than today, then it’s inconceivable that earthquakes did not play a role in the past to affect the cultures that occupied the land along the faults, some of which we do not even know of yet,” said Kovach.

Seismologists look for evidence that suggest an earthquake’s footprint. Sintubin and Niemi cite three distinct types of evidence: faulted and displaced archaeological relics, or “cultural piercing features”; ground-shaking induced damage to buildings and damage induced by secondary phenomena, such as tsunamis; and archaeological evidence, such as repairs to man-made structures.

Kovach looks at the issue of water, such as the damming of rivers and changing elevation of coasts. His research has focused on Banbhore, which is an inland city that was once the ancient coastal city of Debal, the gateway for Islam’s advent in the Indian subcontinent. According to Kovach, the site has witnessed at least four distinct Muslim occupations and three successive reconstructions that correlate to the written record by Arab historians. “There are numerous examples in the Indus Valley that earthquakes did affect the occupying history of these sites,” said Kovach. Today, most of Pakistan and the western states of India occupy the ancient Indus Valley, which experienced the earthquakes that, according to Kovach, altered the course of civilization there over the past millennium.

Sintubin and Stewart are proposing a standardized method to study an archaeological site with the purpose of identifying ancient earthquakes and to evaluate existing archaeoseismological data. The research is currently in process for publication by the Bulletin of the Seismological Society of America. Called the Archeological Quality Factor, or AQF, this proposed evaluative approach would document a degree of certainty of an ancient earthquake recorded at a site. According to Sintubin, the approach reveals the weaknesses in any earthquake hypothesis at a site and constitutes a significant step in the overall acknowledgement of archaeoseismology as a scientific discipline. Sintubin applied the method to research conducted at an excavation in Turkey. The resulting AQF (~5%) turns out to support with some certainty the hypothesis that the region has been struck in the 7th century AD by a previously unknown major earthquake.

While some remain cautious, others are eager to refine the role of earthquakes on past cultures. “A lot can be gleaned from going back to look at old reports,” said Kovach. “Past earthquakes have left an inviting tale of destruction.”

Archaeoseismological Methodologies: Principles and Practices, SSA Annual Convention, 1:30 – 5 PM, Wednesday, 16 April, in the Hilton Hotel, Mesa C

Nan Broadbent | EurekAlert!
Further information:
http://www.seismosoc.org

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>