Earth Observatory Blog

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 20 Sep 2019 by:

At home and abroad there is increasing agreement that we are facing an existential environmental crisis. Death, destruction, and disruption by extreme weather events, haze from forest fires, and contamination of oceans by plastic waste have dramatically increased the awareness of environmental degradation, and given rise to a realisation that the conclusions from decades of scientific research, and the dire predictions arising from it, indeed point to a considerable challenge to society.  

Singapore’s Prime Minister Lee Hsien Loong said in the 2019 National Day Rally speech that “climate change is one of the gravest challenges the human race faces and Singapore is already feeling its impact – which is likely to worsen over the next few decades”. 

Last week...

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...

Submitted on 20 Mar 2019 by:

What lies beneath Singapore?

With land in scarce supply, Singapore is increasingly looking underground for storage spaces and even city construction. A team from the Earth Observatory of Singapore (EOS) have started working on a seismic survey to find out more about Singapore’s underground seismic structure and seismic hazard. A total of 88 seismometers have been deployed at 87 sites across Singapore, including school, parks, nature reserves, and weather stations.

The underground may also hold valuable resources for Singapore, such as water and energy. One example of this is geothermal energy. Hot springs in Singapore are generated by hot rocks deep underground. We want to identify the source of this...

Submitted on 12 Mar 2019 by:

Scientists at the Earth Observatory of Singapore (EOS) and Asian School of the Environment (ASE), at Nanyang Technological University (NTU), and collaborating institutions National University of Singapore and University of Colorado, have demonstrated the potential to use GPS (more generally known as GNSS) technology to track storm surges in coastal settings.

A new study, published on 5 March 2019 in leading journal GPS Solutions, reveals that GNSS signals can be used to track storm surges. Led by EOS Research Fellow, Dr Dongju Peng, the work was supported by a Ministry of Education grant to...

Submitted on 04 Mar 2019 by:

Scientists from Academia Sinica (Taiwan) and the Earth Observatory of Singapore (EOS) have published a study in Science Advances, using a technique developed at EOS for discerning the strength of rocks in Earth’s continental lower crust.

The strength of the lower crust plays an important role in controlling the size and time between earthquakes, as well as the evolution of plate tectonics and growth of mountains over geological time. Using our method we are able to image how the strength of the rocks vary in the lower crust beneath Taiwan, measured by their effective viscosity. If rocks have high effective viscosity, it means they are strong, and...

Submitted on 25 Jan 2019 by:

Magma commonly moves up towards the surface by creating cracks in the crust. It flows inside of the cracks, which grow upwards as the magma applies pressure and damages surrounding rocks. These magma-filled cracks are known as dikes and they are an important form which allows magma to travel easily through the crust.

Nature always finds the easiest path for a dike, so if it takes less pressure to push apart the ground vertically or horizontally, the dike will grow accordingly. This is an important principle that cracks grow perpendicularly to the weakest force and generally in the direction of the highest.

Imagine tearing apart a piece of paper – pulling the paper apart from left to right...

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 20 Dec 2018 by:

Dear EOS Community,

What a busy and exciting year for the Earth Observatory of Singapore (EOS). In early 2018, we kicked off the celebration of our 10thyear as a Research of Excellence at the Nanyang Techonological University (NTU). Marking a decade of geohazard research in Asia, EOS has built a team of outstanding scientists and staff to move the institution forward for years to come.

The celebration began with a much deserved party for our staff and faculty, in early May. People are the key to a successful institution and at EOS, we are no different. Our team of exemplary principal investigators are year-over-year conducting more critical research throughout Asia, which provide vital information to communities in at-risk areas.

Looking back on the past...

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...