Earth Observatory Blog

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 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...

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 14 Nov 2018 by:

On Sunday (29 July 2018), I learnt about the strong 6.4-magnitude (M) earthquake in Lombok, Indonesia. As we have friends living there, I wanted to visit to see what aid we could organise for the people there. So my husband and I went to Lombok with some friends, and we linked up with other humanitarian aid groups to visit the Sembalun area, which is about 1,000 metres above sea level, at the foothills of Mount Rinjani, one of the most scenic volcanoes in the world.

 

At about 6.46 pm the following Sunday (5 August 2018), just as we had finished a meeting to prioritise the relief needs, an earthquake suddenly occurred. It was my first time experiencing a quake, and it really shook the foundations of what I knew about them.

I realised I had many...

Submitted on 06 Oct 2018 by:

Soputan Volcano in north Sulawesi erupts five days after the neighbouring magnitude-7.5 Palu earthquake – Was the eruption triggered by the earthquake?

An eruption from Soputan volcano commenced at 08:47 local time on 3 October 2018, producing a dense ash plume that rose 4 kilometres (km) above the summit and drifted west and northwest. This event occurred five days after the magnitude-7.5 Palu earthquake that caused a disastrous tsunami. The epicentre was located at a depth of 10 km and about 600 km to the west-southwest of Soputan volcano.

Could the eruption have been triggered by the earthquake?

Earthquakes and volcanoes are intimately linked through plate tectonics. Examples of earthquake-volcano interactions namely include the 1975 eruption of Kīlauea...

Submitted on 02 Oct 2018 by:

On 28 September 2018, central Sulawesi in Indonesia got struck by a powerful earthquake measuring 7.5 in magnitude (M). A tsunami that followed later devastated the city of Palu and the town of Donggala, leaving more than a thousand dead and even more homeless.

Associate Professor Adam Switzer, a Principal Investigator at the Earth Observatory, shares with us why this earthquake-tsunami event is a complicated one and what you can do to stay as safe as possible if you were ever caught up in one.

Submitted on 08 Mar 2018 by:

The highly active Sumatran Subduction Zone has produced more than four great earthquakes in the last decade. The first of these was the giant Mw 9.2 Sumatra-Andaman earthquake that ruptured on 26 December 2004. This devastating event was followed by three others – the Mw 8.6 Nias-Simeulue quake in 2005, the Mw 8.4 Bengkulu earthquakes in 2007, and the Mw 7.7 Mentawai tsunami-earthquake in 2010.

In order to understand why so many great earthquakes originate from this region, we have to measure the strength of the rocks in the earth’s lower crust and upper mantle. Our new research, published today on 8 March 2018 in Nature Communications, highlights a ground-breaking new approach to how the strength of these rocks...

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