Earth Observatory Blog

Submitted on 22 Feb 2021 by:

Last December, the Earth Observatory of Singapore (EOS) celebrated the 10th anniversary of its collaboration with the Centre for Volcanology and Geological Hazard Mitigation (CVGHM).

Over the past decade, EOS and CVGHM have shared knowledge, expertise, and adventures through fieldwork, workshops, and publications.

"This long-term collaboration has enabled us to refine eruption histories, unravel magma storage conditions and eruption dynamics, further our understanding of related geophysical signals, and evaluate the implications in terms of hazards in one of the most populated and volcanologically active regions of the world," said Assistant Professor Caroline Bouvet de la Maisonneuve, a Principal Investigator at EOS.

Dr Hanik Humaida, Head of the...

Submitted on 29 Jan 2021 by:

A series of deadly earthquakes struck the Indonesian island of Lombok over three weeks in August 2018, causing widespread damage. These earthquakes were unusual because there were two magnitude-6.9 mainshock events that were each preceded by a smaller foreshock, instead of a single mainshock. The complexity of the earthquake sequence caused great anxiety about when another powerful earthquake might occur.

In our study published in the journal Science Advances, we demonstrate how the complexity of this earthquake sequence is due to the influence of Gunung Rinjani, Lombok’s large active volcano, on the geological fault that hosted the earthquakes.

After the first powerful magnitude-6.4 earthquake...

Submitted on 15 Jan 2021 by:

A moderate earthquake struck western Sulawesi, Indonesia, on 15 January 2021 at approximately 2:28am (SGT). According to the United States Geological Survey, the Mw 6.2 event occurred about 36 kilometres (km) south of Mamuju on the island of Sulawesi at a depth of 18 km.

This event follows a smaller Mw 5.7 foreshock event that occurred approximately 12 hours earlier at about the same location.

Today’s event is due to compressional forces on a fault system that has left a visible record in the topography and geology. However, not many earthquakes have happened on this fault system in the recent past. “The east-dipping thrust fault here is part of an obscure system of faults that extends offshore and is not well studied,” said Dr Kyle Bradley, a Principal...

Submitted on 01 Dec 2020 by:

The activity of Ili Lewotolok (or Lewotolo) volcano ramped up on 29 November 2020 with a series of eruptions. The largest of these eruptions occurred at about 9:45am local/Singapore time (1:45am UTC) and sent a gas and ash plume more than 5 kilometres (km) into the atmosphere. This powerful eruption was recorded by the infrasound network from the Earth Observatory of Singapore (EOS).

Scientists from EOS use infrasound sensors to remotely characterise volcanic eruptions. Even if Ili Lewotolok volcano is about 2,500 km away from Singapore, the eruption on 29 November produced a clear infrasound signal on the Singapore Infrasound Array. The same...

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 21 May 2020 by:

Did you know that in the past six weeks six volcanoes in Indonesia erupted? These volcanoes are Semeru, Anak Krakatau, Merapi, Kerinci, Dukono, and Ibu. 

These recent eruptions are part of the usual volcanic bustle in Indonesia, impacting mostly the areas close to the volcanoes. While some of these activities were picked up all the way in Singapore, all were reported to aviation authorities.

Issuing Eruption Notifications

The Centre for Volcanology and Geological Hazards Mitigation (CVGHM), the monitoring agency for Indonesian volcanoes, issued a Volcano Observatory Notification for Aviation (VONA) on each eruption. The notification includes a summary of the volcanic activity, the...

Submitted on 09 Mar 2020 by:

113 years ago, on 4 January 1907, a powerful magnitude (M) 8.2-8.4 earthquake occurred off the west coast of Sumatra, Indonesia. This earthquake belonged to a special class called “tsunami earthquakes” that do not generate very strong shaking, but can result in large tsunamis.

The tsunami that was produced struck Nias and Simeulue, killing thousands. It also struck the distant shores of Sri Lanka, India, and the island of Reunion. The first earthquake was later followed by another quake measuring approximately M 7.0, resulting in the destruction of countless houses.

In the years that followed, the sequence got jumbled and the two events were conflated as one, but the 1907 disaster was preserved in local memory by way of the legend of the Smong – a Devayan word for...

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...