Paige Magrogan

260559572

Earthquakes and Earth Structure

Olivia Jensen

Earthquake Archaeology of Japan

What is Earthquake Archaeology?

The study of earthquakes and seismic activity in the past and its effects on human societies and

their material culture.

Related Fields

• Paleoseismology- the study of earthquakes many years after their occurrence.

• Ancient fault identification and finding evidence of sediment liquefaction most common.

• Limitations: faults not always visible, weathering and erosion, subsequent disturbance.

• Historical Seismology: the study of written documents that describe past earthquakes.

• Usually determines “size” and frequency.

• Problems: historical descriptions sometimes difficult to interpret, difficulties calibrating

dates for earthquake lists, sometimes seen by seismologists as too qualitative.

Earthquake archaeology uses both fields and is sometimes criticized for using circular reasoning.

But most critics concede that good data is often produced, and it has real applications for risk

assessment today.

What are some archaeological indicators that an earthquake affected a site?

• Collapsed buildings, columns, slipped keystones on arches

• Tilting of floors

• Crushed skeletons from building/cave collapses

What about Japan?

• Possible to draw on extensive historical records and compilations made in 20th century.

• Interest in earthquakes by archaeologists began in 1980s.

• More emphasis after 1995 Kobe earthquake.

• Goals included risk and hazard assessment and to better understand the past.

• Much more focused on geology than Mediterranean context, such as sand dike formation

and soft sediment deformation.

• Result of lack of preservation of buildings (usually wood).

• Chinese pagoda-style surprisingly resistant to earthquakes.

• Pottery and stone tools useful for relative dating (sometimes within 5-year periods).

Liquefaction and Soft Sediment Deformation

• Very common in archaeological record

• Identified using “regional” approach-widespread correlation

• Liquefaction leaves characteristic sand dikes.

• Soft sediment deformation takes many forms, depends on regional context.

• But: danger of conflating several events into one.

• Matsuda Jun-ichiro one pioneer of this research.

Illustration of Sand Dikes Caused by Earthquake Liquefaction

Taken from Barnes (2010).

Example of Wooden Chinese-style Building with Stone Foundation. Nara, Japan.

After the 2011 Sendai Event

• Attention shifted to preservation issues

• Tsunami and nuclear fallout --- many sites now unable to be studied, many cultural

heritage sites waterlogged, archives/artifacts destroyed.

• Tension between desire to move coastal residents to higher ground and desire to save

unexcavated sites there --- luckily for archaeologists, government has sponsored

extensive rescue operations.

• Most people did not know a tsunami could go so far inland, but excavations before 2011

revealed the Jogan earthquake of 869 CE caused such a tsunami.

• Archaeologists regret past lack of public engagement; may have saved lives in 2011.

• “Disaster archaeology” and public engagement considered essential for future practice.

Focused on collaboration and giving people hope that they can recover.

Conclusion

• Earthquake archaeology uses paleoseismology and historical seismology to determine

effects of past earthquakes on human societies.

• Mediterranean researchers focus on building damage, but Japanese researchers focus on

geologic traces.

• Can be more academic or more risk-assessment-based.

• After 2011 earthquake/tsunami, public engagement, solidarity, and rescue excavation

much more emphasized.

References

Barnes, Gina L. 2010. “Earthquake Archaeology in Japan: An Overview.” In Ancient Earthquakes. Edited

by Manuel Sintubin, Iain S. Stewart, Tina M. Niemi, and Erhan Altunel. 81-96. Boulder: The

Geological Society of America.

Grant, Lisa B. 2002. “Paleoseismology.” In International Handbook of Earthquake and Engineering

Seismology. Edited by William Hung Kan Lee. 475-489. Boston: Academic Press.

Guidoboni, Emanuela. 2002. “Historical Seismology: The Long Memory of the Inhabited World.” In

International Handbook of Earthquake and Engineering Seismology. Edited by William Hung

Kan Lee. 775-790. Boston: Academic Press.

Katsuyuki, Okamura, Atsushi Fujisawa, Yasuhisa Kondo, Yu Fujimoto, Tomokatsu Uozu,

Yumiko Ogawa, Simon Kaner, and Koji Mizoguchi. 2013. “The Great East Japan

Earthquake and Cultural Heritage: Towards an Archaeology of Disaster.” Antiquity Volume 87,

Issue 335: 258-269.

Nur, Amos. 2002. “Earthquakes and Archaeology.” In International Handbook of Earthquake and

Engineering Seismology. Edited by William Hung Kan Lee. 765-774. Boston: Academic Press.

Usami, Tatsuo. “Historical Earthquakes in Japan.” In International Handbook of Earthquake and

Engineering Seismology. Edited by William Hung Kan Lee. 799-802. Boston: Academic Press.