#Archaeological #evidence that a late 14th-century #tsunami devastated the coast of northern #Sumatra and redirected history (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Archaeological evidence that a late 14th-century tsunami devastated the coast of northern Sumatra and redirected history

Patrick Daly, Kerry Sieh, Tai Yew Seng, Edmund Edwards McKinnon, Andrew C. Parnell, Ardiansyah, R. Michael Feener, Nazli Ismail, Nizamuddin, and Jedrzej Majewski

PNAS first published May 28, 2019 / DOI: https://doi.org/10.1073/pnas.1902241116

Contributed by Kerry Sieh, April 11, 2019 (sent for review February 8, 2019; reviewed by Roland J. Fletcher, Anthony J. S. Reid, and Ezra B. W. Zubrow)



We demonstrate that a tsunami in the late 14th century CE destroyed coastal sites along a critical part of the maritime Silk Road and set in motion profound changes in the political economy of Southeast Asia. Our results provide a precise chronology of settlement and trade along a historically strategic section of the Sumatran coast and are robust physical evidence for the rise of the Aceh Sultanate. Tragically, coastal areas impacted by the late 14th century tsunami were devastated by the 2004 Indian Ocean tsunami. This makes our findings relevant to debates about hazard mitigation and risk reduction. This example shows that archaeological, historical, and geological data are relevant in discussions about the long-term sustainability of communities exposed to geological hazards.



Archaeological evidence shows that a predecessor of the 2004 Indian Ocean tsunami devastated nine distinct communities along a 40-km section of the northern coast of Sumatra in about 1394 CE. Our evidence is the spatial and temporal distribution of tens of thousands of medieval ceramic sherds and over 5,000 carved gravestones, collected and recorded during a systematic landscape archaeology survey near the modern city of Banda Aceh. Only the trading settlement of Lamri, perched on a headland above the reach of the tsunami, survived into and through the subsequent 15th century. It is of historical and political interest that by the 16th century, however, Lamri was abandoned, while low-lying coastal sites destroyed by the 1394 tsunami were resettled as the population center of the new economically and politically ascendant Aceh Sultanate. Our evidence implies that the 1394 tsunami was large enough to impact severely many of the areas inundated by the 2004 tsunami and to provoke a significant reconfiguration of the region’s political and economic landscape that shaped the history of the region in subsequent centuries.

tsunami – Sumatra – Aceh – postdisaster recovery – hazards

Keywords: Earthquakes; Tsunami; History; Society; Sumatra.



#Evidence of #supershear during the 2018 magnitude 7.5 #Palu #earthquake from space geodesy (Nat Geosci., abstract)

[Source: Nature Geoscience, full page: (LINK). Abstract, edited.]

Evidence of supershear during the 2018 magnitude 7.5 Palu earthquake from space geodesy

Anne Socquet, James Hollingsworth, Erwan Pathier & Michel Bouchon

Nature Geoscience (2019)



A magnitude 7.5 earthquake hit the city of Palu in Sulawesi, Indonesia on 28 September 2018 at 10:02:43 (coordinated universal time). It was followed a few minutes later by a 4–7-m-high tsunami. Palu is situated in a narrow pull-apart basin surrounded by high mountains of up to 2,000 m altitude. This morphology has been created by a releasing bend in the Palu-Koro fault, a rapidly moving left-lateral strike-slip fault. Here we present observations derived from optical and radar satellite imagery that constrain the ground surface displacements associated with the earthquake in great detail. Mapping of the main rupture and associated secondary structures shows that the slip initiated on a structurally complex and previously unknown fault to the north, extended southwards over 180 km and passed through two major releasing bends. The 30 km section of the rupture south of Palu city is extremely linear, and slightly offset from the mapped geological fault at the surface. This part of the rupture accommodates a large and smooth surface slip of 4–7 m, with no shallow slip deficit. Almost no aftershock seismicity was recorded from this section of the fault. As these characteristics are similar to those from known supershear segments, we conclude that the Palu earthquake probably ruptured this segment at supershear velocities.

Synthetic aperture radar data were processed using GMTSAR software, freely available from https://topex.ucsd.edu/gmtsar/.

Optical satellite images were mosaicked using the Geospatial Data Abstraction Library (http://gdal.org) and then correlated using the COSI-Corr software package available at www.tectonics.caltech.edu/slip_history/spot_coseis/download_software.html.

Deformation generated by a static earthquake source was modelled using Okada57 equations implemented in the disloc program (www.physics.hmc.edu/GL/disloc/disloc.c).


Data availability

The data sets generated during the current study (displacement fields from Landsat-8, Sentinel-2 and WorldView image correlation and from the ALOS-2 interferogram, as well as the static slip distribution) are available from the corresponding author upon request. Raw satellite optical imagery was made freely available by ESA (Sentinel-2, https://scihub.copernicus.eu/dhus/#/home), USGS (Landsat-8, https://earthexplorer.usgs.gov/) and DigitalGlobe (WorldView, www.digitalglobe.com/opendata/indonesia-earthquake-tsunami/). Raw ALOS-2 data availability is restricted to PI investigation at www.eorc.jaxa.jp/ALOS/en/aw3d30/data/index.htm.


Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Keywords: Earthquakes; Tsunami; Geology; Indonesia.


#Dynamics and early post- #tsunami #evolution of floating marine #debris near #Fukushima Daiichi (Nat Geosci., abstract)

[Source: Nature Geoscience, full page: (LINK). Abstract, edited.]

Dynamics and early post-tsunami evolution of floating marine debris near Fukushima DaiichiDynamics and early post-tsunami evolution of floating marine debris near Fukushima Daiichi

John Philip Matthews, Lev Ostrovsky, Yutaka Yoshikawa, Satoru Komori & Hitoshi Tamura

Nature Geoscience (2017) / doi:10.1038/ngeo2975

Received 23 February 2017 – Accepted 23 May 2017 – Published online 03 July 2017



The devastating tsunami triggered by the Tōhoku-Oki earthquake of 11 March 2011 caused a crisis at the Fukushima Daiichi nuclear power station where it overtopped the seawall defences. On retreating, the tsunami carried loose debris and wreckage seaward and marshalled buoyant material into extensive plumes. Widespread concern over the fate of these and numerous other Tōhoku tsunami depositions prompted attempts to simulate debris dispersion throughout the wider Pacific. However, the effects of locally perturbed wind and wave fields, active Langmuir circulation and current-induced attrition determine a complex and poorly understood morphology for large floating agglomerations. Here we show that the early post-tsunami evolution of marine-debris plumes near Fukushima Daiichi was also shaped by near-surface wind modifications that took place above relatively calm (lower surface roughness) waters covered by surface films derived from oil and other contaminants. High-spatial-resolution satellite tracking reveals faster-than-expected floating-debris motions and invigorated plume evolution within these regions, while numerical modelling of turbulent air flow over the low-drag, film-covered surface predicts typically metre-per-second wind strengthening at centimetric heights, sufficient to explain the observed debris-speed increases. Wind restructuring probably stimulates the dispersion of flotsam from both biological and anthropogenic sources throughout a global ocean of highly variable surface roughness.

Keywords: Tsunami; Earthquakes; Japan; Nuclear Events; Environmental Disasters; Environmental Pollution.


#Spatiotemporal #Identification of Potential #Tsunami Vertical #Evacuation Sites: A Case Study of #Shizuoka City, #Japan (PLoS Curr., abstract)

[Source: PLoS Currents Disasters, full page: (LINK). Abstract, edited.]

Spatiotemporal Identification of Potential Tsunami Vertical Evacuation Sites: A Case Study of Shizuoka City, Japan


AUTHORS: Gerasimos Voulgaris, Jelena Aleksejeva




The city of Shizuoka directly faces the Nankai Trough (known for its tsunamigenic history), and is facing a potential tsunami threat. In this setting vertical evacuation can be of great significance in reducing loss of life.


We apply a GIS based method in order to identify sites that could be utilized for vertical evacuation within the existing building stock of the city, under two tsunami scenarios of 5 and 10 meters of run-up. For each building, we estimate the volume that is expected to be lost per scenario, as well as the number of people inside and how that number fluctuates over different times of the day.


Using the criteria of 25% or less building volume loss and 6 cubic meters of volume per person, resulted in 2,046 potential sites for the 10 meter scenario and 1,643 potential sites for the 5 meter scenario, with the maximum amount of people that can potentially be accepted in these sites in the morning hours being 873,537 in the 10 meter scenario and 304,734 in the 5 meter scenario.


Our approach has shown that there is a temporal aspect in tsunami vertical evacuation due to the movement of the local population throughout the day. the proposed method can be used for preliminary identification of potential vertical evacuation sites, however, it must be followed by further vulnerability and engineering assessments of buildings, in combination with accessibility and evacuation routing in order to reach a viable and complete evacuation plan.


Field work and technology required for conducting this study has been funded by Sinfonica GIS Statistical research grants.

Keywords: Tsunami; Earthquakes; Japan.


Increased #risk of #dementia in the aftermath of the 2011 Great East #Japan #Earthquake and #Tsunami (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Increased risk of dementia in the aftermath of the 2011 Great East Japan Earthquake and Tsunami

Hiroyuki Hikichi a,1, Jun Aida b, Katsunori Kondo c,d, Toru Tsuboya b, Yusuke Matsuyama b, S. V. Subramanian a, and Ichiro Kawachi a

Author Affiliations: a Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health, Boston, MA 02115; b Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, Sendai, Miyagi 980-8575, Japan; c Center for Preventive Medical Sciences, Chiba University, Chiba-shi, Chiba 260-8670, Japan; d Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8511, Japan

Edited by Susan T. Fiske, Princeton University, Princeton, NJ, and approved September 16, 2016 (received for review May 15, 2016)



Recovery after major disaster poses potential risks of dementia for the elderly population. However, no previous studies have examined exposure to natural disaster and changes in risk factors as predictors of deterioration in cognitive function. We prospectively examined whether housing damage and loss of relatives or friends were associated with cognitive decline in the aftermath of the 2011 Great East Japan Earthquake and Tsunami. In this study, which included 3,566 survivors who are 65 y old or older, the severity of housing damage was significantly associated with cognitive decline after controlling changes of covariates and risk factors during the follow-up period. The cognitive decline should be listed as a health risk of older survivors in the aftermath of natural disasters.



No previous study has been able to examine the association by taking account of risk factors for dementia before and after the disaster. We prospectively examined whether experiences of a disaster were associated with cognitive decline in the aftermath of the 2011 Great East Japan Earthquake and Tsunami. The baseline for our natural experiment was established in a survey of older community-dwelling adults who lived 80 km west of the epicenter 7 mo before the earthquake and tsunami. Approximately 2.5 y after the disaster, the follow-up survey gathered information about personal experiences of disaster as well as incidence of dementia from 3,594 survivors (82.1% follow-up rate). Our primary outcome was dementia diagnosis ascertained by in-home assessment during the follow-up period. Among our analytic sample (n = 3,566), 38.0% reported losing relatives or friends in the disaster, and 58.9% reported property damage. Fixed-effects regression indicated that major housing damage and home destroyed were associated with cognitive decline: regression coefficient for levels of dementia symptoms = 0.12, 95% confidence interval (CI): 0.01 to 0.23 and coefficient = 0.29, 95% CI: 0.17 to 0.40, respectively. The effect size of destroyed home is comparable to the impact of incident stroke (coefficient = 0.24, 95% CI: 0.11 to 0.36). The association between housing damage and cognitive decline remained statistically significant in the instrumental variable analysis. Housing damage appears to be an important risk factor for cognitive decline among older survivors in natural disasters.



1 To whom correspondence should be addressed. Email: hikichi@hsph.harvard.edu.

Author contributions: H.H. and I.K. designed research; H.H., J.A., K.K., T.T., Y.M., S.V.S., and I.K. performed research; H.H. analyzed data; and H.H., J.A., K.K., T.T., Y.M., S.V.S., and I.K. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1607793113/-/DCSupplemental.

Keywords: Japan; Dementia; Mass Casualty Events; Earthquakes; Tsunami.