Earth Observatory Blog

Why We Need to Learn What We Can About Powerful Earthquakes

Submitted on 06 Aug 2020 by:

In conversation with Assistant Professor Aron Meltzner, Principal Investigator at the Earth Observatory of Singapore

 

1. How does the recent powerful magnitude-7.8 earthquake in Alaska remind us of similar hazards in Southeast Asia?

Last week, we saw a powerful earthquake off the coast of Alaska with a magnitude of 7.8 which had the potential to trigger a damaging tsunami, but fortunately this did not happen.

It occurred along a subduction zone where the Pacific Plate is subducting or slipping under the North American plate. The shaking that we know as an earthquake results from the sudden movement between these two plates, but that sudden movement also has the potential to lift up the seafloor, which in turns lifts the water above it, and that can...

Read more

Using Large Earthquakes to Understand Singapore’s Underground Structure

Submitted on 15 Jun 2020 by:

The first results from Singapore’s first island-wide seismic survey unravel some important features of Singapore’s underground.

In March of last year, a team at the Earth Observatory of Singapore (EOS) recorded the ground movements of Singapore using 88 seismometers placed in locations such as schools, parks and weather stations.

We collected a vast quantity of fascinating data using distant earthquakes to image Singapore’s subsurface, and our first set of results were recently published in the journal Geophysical Research Letters.

Seismologists use a technique called receiver functions to look at boundaries between different rocks...

Read more

Understanding the 2018 Palu Earthquake

Submitted on 30 Sep 2019 by:

Just after 6pm on 28 September 2018 (Singapore time), a magnitude-7.5 earthquake struck central Sulawesi. The powerful quake generated a tsunami which, along with massive landslides, devastated Palu and the town of Donggala. These resulted in more than 4,000 people dead or missing.

In an economic loss assessment report issued by Indonesia's National Disaster Management Agency (BNPB), the Palu earthquake event caused more than S$1.5 million in damages.

Today, a year later, scientists from the Earth Observatory of Singapore (EOS) and their teams are ready to share some of their findings about this earthquake-tsunami event.

A Complex Rupture Sequence

Using a combination of seismic, geodetic, geologic, and written records, Assistant Professor Wei...

Read more

Why the 2018 Palu Landslides Were So Deadly

Submitted on 28 Sep 2019 by:

During the early evening of 28 September 2018, a magnitude-7.5 earthquake struck along the coast of northwestern Sulawesi, Indonesia. This region hosts a famous strike-slip fault system called the Palu-Koro Fault.

Even though this is one of the fastest slipping faults in the world, it has not produced many large earthquakes during historical times. The Palu-Koro Fault was therefore thought to have a high probability of a large and destructive earthquake, and so the occurrence of the 2018 quake in Sulawesi wasn’t very surprising.

However, the landsliding that was triggered by the earthquake turned out to be unexpectedly destructive. Soon after the earthquake, witnesses described entire villages south of Palu City sinking into mud and disappearing, and it was...

Read more

Powerful Twin Quakes Strike Southern California

Submitted on 09 Jul 2019 by:

 

On 5 July 2019 at 1.33am (Singapore time), a Mw 6.4 earthquake struck the town of Ridgecrest in California. Its seismic waves could be felt from Los Angeles to San Jose. Nearly a day and a half later, on 6 July at 11.19am (Singapore time), a more powerful Mw 7.1 quake struck the same region. Because the Mw 7.1 earthquake is the largest event so far in this sequence, it is considered to be the mainshock. The events leading up to it, which include the Mw 6.4 quake, are considered to be foreshocks.

From this sequence of earthquakes, it is clear that the Mw 6.4 foreshock had triggered seismicity on conjugate faults (i.e. intersecting faults that criss-cross in a X-shape) along the Eastern California Shear Zone which runs somewhat parallel to the San Andreas Fault, but is...

Read more

How a Powerful Tsunami Shaped the History of Aceh

Submitted on 30 May 2019 by:

I went to Banda Aceh, Indonesia in 2006 to help assess the impact of the 2004 Indian Ocean tsunami upon the region’s rich cultural heritage. The scale of destruction caused by the tsunami was staggering. Half the city had been pulverised and all that was left was a mix of concrete, broken furniture, household items, and a colorful patchwork of shreds of clothing. We found clusters of beautifully carved stone grave markers dating back centuries amongst the rubble, half buried in mud and debris, or piled up neglected near areas being cleared by NGOs and donors for new tracts of post-disaster housing.

The same waves that killed over 150,000 people and displaced millions had reached back into the past and threatened to wipe out the historical memories of Aceh’s coastal...

Read more

Professor Kerry Sieh Shares his Insights on Indonesia’s Shattered Paradise, Lombok

Submitted on 18 Feb 2019 by:

On 29 July 2018, Lombok was struck by a 6.4-magnitude earthquake, killing 20 people. A week later, an even stronger earthquake of magnitude 6.9 devasted the island. Strong aftershocks continued to rock the Indonesian island, quickly transforming the popular tourist paradise into “hell on earth”.

In an episode of Channel NewsAsia’s Insight titled "Lombok: A Shattered Paradise", aired on 7 September 2018, Prof Sieh provided insights on how tectonic plate movements could result in tsunamis, volcanic activities, as well as devastating earthquakes. Using the analogy of a cracked windshield on a car, Prof Sieh explained how aftershocks are produced from faults during an earthquake. In some instances, an aftershock can trigger a more powerful earthquake. This is possibly what...

Read more

Jumping Earthquakes – One Fault at a Time

Submitted on 10 Oct 2018 by:

Published in Nature Geosciences on 1 October 2018, new research by a team of scientists from the Victoria University of Wellington and the Earth Observatory of Singapore (EOS) has revealed how understanding the events leading up to the 2016 Kaikoura earthquake may lead to a different approach to forecasting earthquakes.

The Kaikoura earthquake, which measured Mw 7.8 in magnitude, had struck the South Island of New Zealand in 2016. It resulted in a rupture that stretched over 200 kilometres (km), ripping through 21 faults – a world record for the most number of faults observed to rupture in a single earthquake event.

It is now rightly regarded as the most complex earthquake ever to be studied, and has...

Read more

Today's Quake in Myanmar is a Reminder of How Active the Sagaing Fault is

Submitted on 12 Jan 2018 by:

Very early in the morning on Friday, 12 January 2018, Myanmar was struck by a magnitude-6.0 earthquake. Residents in the two capital cities, Yangon and Nay Pyi Taw, were able to feel the quake that had originated 40 kilometres west of the Sagaing Fault in Central Myanmar.

In the video below, Dr Wang Yu, a Research Fellow at the Earth Observatory of Singapore, suggests that today’s earthquake is a reminder of how active the Sagaing Fault actually is. 
Read more

Post-Disaster Damage Assessments: Room for Improvement?

Submitted on 26 Oct 2017 by:

On 25 April 2015, a 7.8-magnitude earthquake struck Nepal, destroying buildings and infrastructure across 31 of Nepal’s 70 districts. Approximately 9,000 people lost their lives to the earthquake that day, 22,000 suffered from injuries, and eight million were affected.

I arrived in Kathmandu one week after the quake, as part of the World Bank disaster risk management team, to support the government of Nepal in various response and recovery activities.

In the days before getting on the plane, I worked with the Stanford Urban Resilience Initiative to develop an initial earthquake impact estimate, based on an impact model I had already developed for Nepal.

I had been researching the seismic risk of Kathmandu for my PhD at Stanford. More specifically, I was...

Read more

Pages