Nav: Home

Rice irrigation worsened landslides in deadliest earthquake of 2018 finds NTU study

October 08, 2019

Irrigation significantly exacerbated the earthquake-triggered landslides in Palu, on the Indonesian island of Sulawesi, in 2018, according to an international study led by Nanyang Technological University, Singapore (NTU Singapore) scientists.

The 7.5 magnitude earthquake struck the Indonesian city on 28 September 2018, taking the lives of over 4,300 people, making it the deadliest earthquake in the world that year.

Writing in Nature Geoscience, researchers from NTU Singapore's Earth Observatory of Singapore (EOS) and the Asian School of the Environment (ASE), together with collaborators from institutions in Indonesia, the United States, the United Kingdom, China and Australia, reveal that the landslides in Indonesia's Palu Valley resulted from widespread liquefaction in areas that were heavily irrigated for rice cultivation.

A century-old aqueduct, constructed to bring enough water into the Palu Valley to irrigate rice, artificially raised the water table to almost ground level. This elevation increased the potential for liquefaction - a situation where buried sediment becomes fluid-like due to strong seismic ground-shaking.

The combination of this fluid-like sediment and the slope of the valley floor exacerbated the catastrophe, creating wide lateral spreading of water, landslides, and debris, which swept through the villages.

This deadly cocktail marked Indonesia´s deadliest earthquake since Yogyakarta in 2006.

"This event is a wake-up call for any area where active faults and irrigation coincide," said Dr Kyle Bradley, a principal investigator at NTU's EOS who led the research.

"We need to improve the awareness and understanding of liquefaction-related landslides and pay closer attention to places where irrigation has artificially raised the water table, said Dr Bradley, who is also a lecturer at NTU's ASE.

The research highlights the urgency for Southeast Asian nation-states to review locations with intensive rice farming activities which lie among active faults.

Dr Bradley said, "This is of particular concern in Southeast Asia as the pace of development is often faster than the return time of large earthquakes - the average time period between one earthquake and the next. Most other similarly irrigated areas have not yet been tested by extreme ground shaking, and some of those areas could also pose a major hazard."

Research used historic and current satellite data

By analysing satellite images taken before and after the earthquake to identify areas affected by landslides, NTU researchers discovered that irrigated paddies and fields were strongly affected, while areas planted with trees were more stable.

This suggested that heavy irrigation and a raised water table were responsible for creating a new liquefaction hazard.

"Hazards that are created by humans can often be more readily moderated than other natural hazards. Based on the relative resiliency of areas planted with mixed tree crops and irrigated fields, we propose that more intermixed planting could decrease the hazard of large landslides in the future," said Dr Bradley.

The satellite image mapping was complemented by field observations of the landslides and of the local irrigation system and practices, produced by an international team of scientists led by Dr Ella Meilianda of the Tsunami and Disaster Mitigation Research Center at Syiah Kuala University in Banda Aceh.

Professor Thomas Dunne of the Bren School of Environmental Science and Management at the University of California, Santa Barbara, who was not affiliated with the study, said "The study has demonstrated how Earth scientists with strong field-based understanding of land surface mechanics can use the rapidly growing toolbox of remote sensing to analyse dangerous processes. The landscape-scale survey approach could be applied elsewhere for systematic assessment and avoidance of dangers that are often overlooked when large infrastructure is first proposed in rapidly developing, but potentially unstable terrains."

The research team plans to continue their study by assessing the effects of local land use on outcomes during the Palu earthquake.
-end-
Notes to Editor:

Paper titled "Wet rice cultivation enabled the earthquake-triggered 2018 Palu valley landslides", published in Nature Geoscience, 27 Sep 2019. https://www.nature.com/articles/s41561-019-0444-1

Researchers from the following institutions were involved in this study:
  • Asian School of the Environment, NTU Singapore

  • Earth Observatory of Singapore, NTU Singapore

  • Tsunami Disaster and Mitigation Research Center (TDMRC), Syiah Kuala University, Banda Aceh, Indonesia

  • Department of Earth Sciences, Durham University, United Kingdom

  • School of Geosciences, University of Sydney, Australia

  • School of Geosciences and Info-Physics, Central South University, No.932 South Lushan Road, Changsha, Hunan 410083 People's Republic of China

  • Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States of America
Media contact:

Mr Nur Amin Shah
Manager, Media Relations
Corporate Communications Office
Nanyang Technological University, Singapore
Email: aminshah@ntu.edu.sg

About Nanyang Technological University, Singapore

A research-intensive public university, Nanyang Technological University, Singapore (NTU Singapore) has 33,000 undergraduate and postgraduate students in the Engineering, Business, Science, Humanities, Arts, & Social Sciences, and Graduate colleges. It also has a medical school, the Lee Kong Chian School of Medicine, set up jointly with Imperial College London.

NTU is also home to world-class autonomous institutes - the National Institute of Education, S Rajaratnam School of International Studies, Earth Observatory of Singapore, and Singapore Centre for Environmental Life Sciences Engineering - and various leading research centres such as the Nanyang Environment & Water Research Institute (NEWRI) and Energy Research Institute @ NTU (ERI@N).

Ranked 11th in the world, NTU has been placed the world's top young university for the past six years. The University's main campus is frequently listed among the Top 15 most beautiful university campuses in the world and it has 57 Green Mark-certified (equivalent to LEED-certified) building projects, of which 95% are certified Green Mark Platinum. Apart from its main campus, NTU also has a campus in Novena, Singapore's healthcare district.

For more information, visit http://www.ntu.edu.sg.

Nanyang Technological University

Related Earthquake Articles:

Typhoon changed earthquake patterns
Intensive erosion can temporarily change the earthquake activity (seismicity) of a region significantly.
Cause of abnormal groundwater rise after large earthquake
Abnormal rises in groundwater levels after large earthquakes has been observed all over the world, but the cause has remained unknown due to a lack of comparative data before & after earthquakes.
New clues to deep earthquake mystery
A new understanding of our planet's deepest earthquakes could help unravel one of the most mysterious geophysical processes on Earth.
Fracking and earthquake risk
Earthquakes caused by hydraulic fracturing can damage property and endanger lives.
Earthquake symmetry
A recent study investigated around 100,000 localized seismic events to search for patterns in the data.
Crowdsourcing speeds up earthquake monitoring
Data produced by Internet users can help to speed up the detection of earthquakes.
Geophysics: A surprising, cascading earthquake
The Kaikoura earthquake in New Zealand in 2016 caused widespread damage.
How fluid viscosity affects earthquake intensity
A young researcher at EPFL has demonstrated that the viscosity of fluids present in faults has a direct effect on the intensity of earthquakes.
Earthquake in super slo-mo
A big earthquake occurred south of Istanbul in the summer of 2016, but it was so slow that nobody noticed.
A milestone for forecasting earthquake hazards
In a new study in Science Advances, researchers report that their physics-based model of California earthquake hazards replicated estimates from the state's leading statistical model.
More Earthquake News and Earthquake Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Debbie Millman: Designing Our Lives
From prehistoric cave art to today's social media feeds, to design is to be human. This hour, designer Debbie Millman guides us through a world made and remade–and helps us design our own paths.
Now Playing: Science for the People

#574 State of the Heart
This week we focus on heart disease, heart failure, what blood pressure is and why it's bad when it's high. Host Rachelle Saunders talks with physician, clinical researcher, and writer Haider Warraich about his book "State of the Heart: Exploring the History, Science, and Future of Cardiac Disease" and the ails of our hearts.
Now Playing: Radiolab

Insomnia Line
Coronasomnia is a not-so-surprising side-effect of the global pandemic. More and more of us are having trouble falling asleep. We wanted to find a way to get inside that nighttime world, to see why people are awake and what they are thinking about. So what'd Radiolab decide to do?  Open up the phone lines and talk to you. We created an insomnia hotline and on this week's experimental episode, we stayed up all night, taking hundreds of calls, spilling secrets, and at long last, watching the sunrise peek through.   This episode was produced by Lulu Miller with Rachael Cusick, Tracie Hunte, Tobin Low, Sarah Qari, Molly Webster, Pat Walters, Shima Oliaee, and Jonny Moens. Want more Radiolab in your life? Sign up for our newsletter! We share our latest favorites: articles, tv shows, funny Youtube videos, chocolate chip cookie recipes, and more. Support Radiolab by becoming a member today at Radiolab.org/donate.