Earth Observatory Blog

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...

Submitted on 02 Jul 2020 by:

On 22 December back in 2018, Indonesia’s Anak Krakatau volcano erupted. The collapse of its flank triggered a tsunami that killed more than 400 and injured at least 30,000 people. 

To understand how the events of that day unfolded with such catastrophic effect, an international research team led by Research Associate Anna Perttu from the Earth Observatory of Singapore (EOS) turned to the data collected from monitoring stations from all around the region, official reports, as well as satellite and visual observations.

Eruptions produce a wide range of signals. Humans can see and hear some of them only when close enough to the eruption. Monitoring instruments help fill the gap. Satellites can be used to image volcanic plumes that are too high or obstructed from an...

Submitted on 05 Nov 2019 by:

Today is World Tsunami Awareness Day. It is a timely opportunity to create greater global awareness about tsunamis as a geological hazard. Before asking how we can stay safe (or safer) from tsunamis, we must first think about how we might improve on the resilience of our current and future infrastructure.

Let’s start by looking at what a tsunami is. A tsunami is a series of waves caused by an underwater earthquake, a volcanic eruption, a landslide, or meteorological processes (meteo-tsunamis). 

So why is SE Asia vulnerable to tsunami hazards? First of all, SE Asia lies in a complex tectonic setting that contains many fault systems and volcanoes. Coupled with a high population density and a tight network of infrastructure in coastal areas, one can imagine just how...

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...

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...

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...

Submitted on 27 Dec 2018 by:

At approximately 9:30pm local time (2:30pm GMT) on the 22nd December 2018, a tsunami struck Indonesia’s Sunda Strait, which lies between the islands of Java and Sumatra, claiming over 430 lives. According to Indonesia’s disaster agency there are at least 1,500 injured, over 120 people still missing, and around 12,000 people have been displaced.

The tsunami occurred during a local holiday for the December solstice, striking a number of popular tourist destinations, including the Tanjung Lesung beach resort in the west of Java. Eyewitness reports indicate there were two separate waves, with the second, larger wave causing the most damage. 

The tsunami was caused by a violent eruption of Anak Krakatau (Fig. 1), the "child" of Krakatoa, in the Sunda Strait....

Submitted on 15 Aug 2018 by:

A one-metre rise in sea level could dramatically increase the frequency of flooding up to almost five times for tsunami-safe Macau, in a new study led by scientists from Nanyang Technological University, Singapore (NTU Singapore). 

The team of scientists from NTU’s Earth Observatory of Singapore (EOS) and Asian School of the Environment (ASE), used computer modelling, and initially showed that Macau, a densely populated coastal city in China, is relatively safe from tsunamis as it requires an earthquake larger than 8.8-magnitude to cause widespread tsunami floods.

However, with just a sea level rise of 0.5 metres, the tsunami-induced flood risk increases to up to 2.4 times and with a 1 metre rise, up to 4.7 times. 

The increased flooding frequency was...

Submitted on 18 Jan 2018 by:

In 2004, a devastating tsunami struck coastlines around the Indian Ocean. While studying the long-term recovery of the city of Banda Aceh, Indonesia, we found that reconstruction aid provided mostly near the coast, combined with many people's preferences to move to safer areas instead, has had the unintended consequence of the poor becoming disproportionately exposed to coastal hazards.

We published these findings on 8 January in Nature Sustainability. For this and other studies, researchers from the Earth Observatory of Singapore (EOS) at Nanyang Technological University teamed up with our colleagues at the International Centre for Aceh and Indian...