Etched in stone: tracing earthquakes through archaeological ruins

The Shore Temple at Mahabalipuram, Tamil Nadu, India

Feature image: Shore Temple at Mahabalipuram, Tamil Nadu, India by Nireekshit, CC BY-SA 3.0

Article: Archaeoseismological potential of the Indian subcontinent

Authors: Miklós Kázmér, Ashit Baran Roy and Siddharth Prizomwala

India’s ancient monuments whisper more than just stories of past empires and civilizations: they also tell tales of its geological past. Evidence of earthquakes is etched in stone, displacements and warps that can help us identify past seismic events.

India’s documentation of earthquakes is sketchy, pieced together from historical data, monographs, and British records. In 1898, the first seismograph was established in Pune, Maharashtra, but serious instrumental recording only began when the 1967 Koyna Dam earthquake struck.Such a short record is not enough to map out active seismic regions or understand recurring earthquakes, so some scientists are turning to archaeological evidence.

Archaeoseismology studies past earthquakes by analysing damage to archaeological sites. How much damage an earthquake does to a structure depends on how hard or soft the ground beneath is, and damage may be mitigated through preventative building techniques. Earthquakes can result in shifts and tilts in masonry or brickwork, displaced walls, warped floors, missing sections, and sometimes, a complete collapse of the structure. The Earthquake Archaeological Effects (EAE) scale helps categorise the intensity of past earthquakes based on observations of structural damage.

A recent paper by Kazmer et al., looks at earthquake damage to 3 late medieval UNESCO World Heritage sites: Mahabalipuram in Tamil Nadu (7th-8th CE), the Qutub Minar complex in Delhi (12th-19th CE), and Konark near Bhubaneshwar in Odisha state (13th CE). All three sites feature masonry buildings commonly seen in 7th and 12th centuries CE architecture across the Indian subcontinent. The seismic history of the subcontinent is understudied compared to the seismically active Himalayan terrain.

The tilt of masonry wall and floor at the Shore Temple in Mahabalipuram indicates liquefaction, a sudden loss of soil stability that can be caused by a seismic shock.. In the Qutub Minar complex, damage to the minar including masonry blocks at the top of Iltutmish’s tomb with gaps of about 5 cms  are attributed to an earthquake in 1803. At Konark, smaller temples around the Sun Temple display shifted blocks. Other temples are missing a shikhara or deul, the temple spire or tower, which might have been toppled by an earthquake.

Beyond categorising such damage, archaeoseismology can indicate the date or date interval, location, and intensity for both seismically active and less active regions. Comparisons with historical records can offer broader insights into the Indian subcontinent. The volcanic plateau that forms the Indian peninsula has long been considered a ‘stable’ region, yet all 3 sites in this study located on the ‘Indian shield’ indicate otherwise – the region has seen earthquake activity in the past. 

Over the years, monuments have undergone intensive restoration by various rulers, British colonial authorities and the Archaeological Survey of India to preserve them for future generations, but in the process, the evidence of past earthquakes has been erased. Kazmer and co-authors suggest that archaeoseismic studies are conducted before all large-scale restoration projects. That way, we can ensure both the historical and geological legacies are preserved for posterity.


Etched in stone: tracing earthquakes through archaeological ruins by Devayani Khare is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Will Atmospheric Rivers Shift from Helpful to Harmful due to Climate Change?

Feature Image by mirobo on Pixabay

Article: The Shifting Scales of Western U.S. Landfalling Atmospheric Rivers Under Climate Change
Authors: Rhoades, A. M., Jones, A. D., Srivastava, A., Huang, H., O’Brien, T. A., Patricola, C. M., Ullrich, P. A., Wehner, M., and Zhou, Y.

While residents of the West Coast of the United States usually don’t have to worry about hurricanes, snow storms, or tornadoes, every winter they do experience extreme weather events known as atmospheric rivers. Atmospheric rivers are plumes of highly concentrated water vapor in the atmosphere. When they move over land, they can produce very heavy rainfall that can cause flooding and even trigger landslides. However, atmospheric rivers are not all bad; in fact, some might even say they’re essential. They provide up to half of California’s rainfall every year, which is beneficial for agriculture and water supply. Like all weather events, atmospheric rivers are impacted by climate change, so how will they be different in a few decades? This question is essential for water resource managers and regular residents of the West Coast, since atmospheric rivers can both help and harm their livelihoods.

Continue reading “Will Atmospheric Rivers Shift from Helpful to Harmful due to Climate Change?”

Cooking up crystals in record time

Featured image: Example of the rock type Pegmatite. Here, crystals of the mineral tourmaline (light-dark green color), and crystals of the mineral lepidolite (pink-purple color) can be seen, sourced from Wikipedia. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Paper: Episodes of fast crystal growth in pegmatites

Authors: Patrick R. Phelps, Cin-Ty A. Lee, Douglas M. Morton

Anyone who has ever wandered along a pebble-ridden beach or a mountainous trail has likely picked up a rock or two, and maybe these rocks contained an array of different crystals (see image above). Perhaps these rocks then skipped along the surface of a still lake, or made their way into the pockets of a snack-ridden backpack, either to never be seen again or to be added to an ever-growing rock collection. Yet, these little pieces of Earth’s history have the potential to do so much more. With the right tools, the crystals within these rocks can be used to inform us of the geological processes that have shaped our planet Earth.

Continue reading “Cooking up crystals in record time”

Shaken, rattled, and rolled

Featured image: an aerial photograph of the Capitolias/Beit-Ras theater, courtesy of the Aerial Photographic Archive of Archaeology in the Middle East (APAAME), CC-BY-NC-ND 2.0

Paper: Two inferred antique earthquake phases recorded in the Roman theater of Beit-Ras/Capitolias (Jordan)
Authors: M. Al-Tawalbeh, R. Jaradat, K. Al-Bashaireh, A. Al-Rawabdeh, A. Gharaibeh, B. Khrisat, and M. Kázmér

One of the biggest questions in earthquake seismology is whether we can see into the future, to forecast seismic activity based on what we know about faults and how they behave. We’re about as likely to accurately predict earthquakes as we are to see the future in a crystal ball, but one way we can improve our forecasts of seismic hazard actually involves looking in the other direction: back into the past.

Continue reading “Shaken, rattled, and rolled”

To P, not to P? That is (an oversimplification of) the biogeochemical question—

Paper: Unraveling biogeochemical phosphorus dynamics in hyperarid Mars‐analogue soils using stable oxygen isotopes in phosphate

Authors: Jianxun Shen, Andrew C. Smith, Mark W. Claire, Aubrey L. Zerkle

Many geologists believe that ancient Mars, with its warmer temperatures and water-rich environment, may have been home to life. To test this hypothesis, astrobiologists must find signifiers of life that can survive the billions of years of hyperaridity experienced on the Martian surface. One such method could be identifying biotic alteration of the geochemical cycling of phosphorus, as was highly publicized during the recent discovery of phosphine in the atmosphere of Venus. Researchers have taken the first step in this search by characterizing biological phosphorus cycling in the analog environment of the Atacama Desert – an endeavor that has applied novel techniques in chemistry to provide insights about the movement of phosphorus in arid environments.

Continue reading “To P, not to P? That is (an oversimplification of) the biogeochemical question—”

It’s complicated; deciphering mixed signals of the carbon-climate relationship in Earth’s past

Paper: High-latitude biomes and rock weathering mediate climate-carbon cycle feedbacks on eccentricity timescales.

Authors: David De Vleeschower, Anna Joy Drury, Maximilian Vahlenkamp, Fiona Rochholz, Diederik Liebrand & Heiko Pälike

Featured image: Benthic foraminifera collected from the North Sea in 2011. Image courtesy of Hans Hillewaert, licensed under CC BY-SA 4.0

Faced with a rapidly warming world, we all have the same questions on our collective minds: how will climate change restructure Earth and what can we do to adapt to those changes? One thing we do know is that the climate is intimately connected to the carbon cycle. When large amounts of carbon get moved between reservoirs (on land and in the ocean and atmosphere), changes in climate ensue. Currently, carbon stored on land is being moved to the atmosphere through anthropogenic CO2 emissions, causing global warming and its various cascading effects. What’s more, looking back in Earth’s history, researchers have established that moving carbon from the atmosphere to the ocean, or back onto land, has had a cooling effect. Just this past year, researchers from the University of Southampton investigated several factors affecting past carbon-climate connections, offering new understandings that could help address climate action moving forward.

Continue reading “It’s complicated; deciphering mixed signals of the carbon-climate relationship in Earth’s past”

Muddy waters lead to decreased oxygen in Chesapeake Bay

Featured Image: Plumes of muddy, sediment-laden water at the Chesapeake Bay Bridge near Annapolis, MD. Photo courtesy of Jane Thomas/ IAN, UMCES.

Paper: Seabed Resuspension in the Chesapeake Bay: Implications for Biogeochemical Cycling and Hypoxia
Authors: Julia Moriarty, Marjorie Friedrichs, Courtney Harris

A memorable feature of the Chesapeake Bay, the largest estuary in the USA, is that the water is very murky and looks like chocolate milk. Former Senator Bernie Fowler has conducted public “wade-ins” over the past 50 years in one of the Bay’s tributaries, seeing how deep the water is before he can no longer see his white tennis shoes, and let’s just say it is never very deep. This is because of the high concentrations of sediment, or small particles of sand and organic material, in the water. Besides making it harder for seagrasses to grow and serving as food for the economically-important oyster, sediment impacts the biological processes that determine how much oxygen and nutrients are available in the water for algae and fish.

Continue reading “Muddy waters lead to decreased oxygen in Chesapeake Bay”

Mosaics of Life Along a River

Featured Image: Small headwater stream in Oregon’s Mountains. Image courtesy Jessica Buser-Young, used with permission.

Paper: The River Continuum Concept

Authors: Robin L. Vannote, G. Wayne Minshall, Kenneth W. Cummins, James R. Sedell, Colbert E. Cushing

Perhaps last time you went for a hike, you stumbled upon a burbling spring pushing its way up through the leaf litter after a heavy rainfall, creating a tiny rivulet of water crisscrossing over your path before plunging back into the forest. What a find! Excitedly, you squatted down and gently uncovered the spring to notice gnats lazily floating away, some nearby fruiting mushrooms, and great clumps of decomposing twigs and leaves which you assume harbor uncountable numbers of microorganisms. This unique little ecosystem is profiting from the nutrients and water being pushed from the ground, using the opportunity to have a feast. But what happens to the nutrients and carbon that gets past these plants and animals?

Continue reading “Mosaics of Life Along a River”

Capturing Early Sun within meteorite inclusions

Paper: Astronomical context of solar system formation from molybdenum isotopes in meteorite inclusions.

Featured image: Artistic impression of the protoplanetary disk. Image used with permission from Wikipedia (A. Angelich).

Authors: Gregory A. Brennecka, Christoph Burkhardt, Gerrit Budde, Thomas S. Kruijer, Francis Nimmo, Thorsten Kleine.

If you ask a cosmochemist what the oldest objects in the solar system are, they will swiftly answer the Calcium Aluminium Inclusions (CAIs), a small light-coloured inclusion within primitive meteorites known as Chondrites (see figure 2C). However, if you ask what event in the solar system evolution CAIs correspond to, it is a more challenging question. Previously, CAI formation was associated with the various evolutionary stages of our Sun.  However, as the timescale of evolution of Sun, calculated to be around 1 million years by observing Sun like stars, is longer than the CAI forming period (~ 40,000 – 200,000 years), the association between CAI formation and the early stages of our Sun is not always clear. In a quest to put the CAI formation in an astronomical context, a recent study from Brennecka et al. analysed CAIs present within various Carbonaceous chondrite meteorites and linked the CAI formation to a specific stage in the Sun’s evolution.

Continue reading “Capturing Early Sun within meteorite inclusions”