Earth Observatory Blog

Submitted on 20 Jan 2022 by:

Volcanic eruptions are sometimes accompanied by clouds of ash and hot gases that travel down the slopes of volcanoes at tens of kilometres per hour. These clouds, called pyroclastic density currents (PDCs), are some of the deadliest volcanic hazards. And as we cannot easily study them in real-time, we took another approach to quantify some of the features that make them so dangerous: their speed, temperature, height, and how far they travelled.

PDCs are often controlled by gravity. They therefore usually flow from high to low elevation and follow the easiest path allowed by topography. This means that PDCs most frequently flow in channels, allowing scientists and government planners to foresee which direction they might go in the event of an eruption.

Although they travel...

Submitted on 16 Dec 2021 by:

A major earthquake struck off the coast of Indonesia in the Flores Sea on 14 December 2021 at approximately 11:20am (Singapore time). According to the United States Geological Survey, the magnitude-7.3 earthquake occurred off the north coast of Flores, about 110 kilometres (km) from Maumere, at a depth of 16 km. The Badan Meteorologi, Klimatologi, dan Geofisika (BMKG), the Indonesian meteorology, climatology, and geophysical agency, issued tsunami warnings for the region but no significant tsunami was detected. 

The Flores Sea region is a seismically active region with complex tectonics because it lies at the junction of several tectonic plates including the Indo-Australian plate, the Sunda plate, and other small tectonic plates. 

This Mw 7.3 earthquake is not a...

Submitted on 06 Dec 2021 by:

On 4th December 2021 at around 2pm local time, Semeru volcano, located in Eastern Java, Indonesia, generated lahars and large flows of volcanic rocks and ash. Badan Nasional Penanggulangan Bencana (BNPB), the Indonesia national disaster management authority, reported that the volcanic activity has killed more than ten people and injured dozens. The Center for Volcanology and Geological Hazard Mitigation (CVGHM), which monitors Semeru and all Indonesian volcanoes, maintains the volcanic alert level at 2 (advisory) on a scale of 1 to 4.

Semeru is the tallest volcano in Java and one of the most active volcanoes in Indonesia. Its current eruptive period started in April 2014, with frequent ash plumes, pyroclastic flows, and rock avalanches. Some incandescence can often be...

Submitted on 10 Nov 2021 by:

On 25 October 2010 at 9:42 PM local time, the people living on the southern Mentawai islands, a chain of islands located off Sumatra, Indonesia, felt a slow, gentle rocking of the rocks below their feet1. Initial reports of the earthquake indicated that a magnitude-7 to -7.2 earthquake had occurred seaward of the islands2. Five to 10 minutes later, a large wave inundated the western coasts of the islands, locally flooding areas more than 10 metres above the ground surface1. Together, the earthquake and tsunami killed more than 400 people and left 300 missing.

Such a large tsunami would typically require an earthquake of magnitude greater than 8. In this case, while the early data from the Mentawai earthquake suggested a much smaller event, a more complete assessment of...

Submitted on 15 May 2021 by:

A strong earthquake struck the Nias region off the west coast of Sumatra, Indonesia, on 14 May 2021 at approximately 1:33pm (Singapore time). According to the United States Geological Survey (USGS), the magnitude-6.6 earthquake occurred at a depth of about 10 kilometres.

Based on information provided by the USGS, yesterday’s earthquake occurred within the Indo-Australian plate, where it bends before subducting under the Eurasian plate. As the plate bends, it can break and generate what is known as an outer-rise earthquake.

Yesterday’s earthquake is not a megathrust event as it did not occur at the boundary between the two tectonic plates, unlike the 2004 Great Sumatran earthquake. "It demonstrates how subduction zones are not just simple plate boundaries but...

Submitted on 21 Apr 2021 by:

Visitors to the Earth Observatory of Singapore (EOS) will be familiar with the exhibition of polar and tropical marine wildlife by some of the world’s leading photographers.

The driving force behind the ‘Elysium Epic Trilogy’ exhibition is Mr Michael Aw, the entrepreneurial underwater photographer who organised three expeditions to the Arctic, Antarctic, and Coral Triangle to document the species featured in this unique exhibition.

The locations of three disparate Elysium expeditions share one common feature – they are all in the front line of climate change. Of his experiences in the Antarctic, the Arctic, and the Coral Triangle, Michael set the scene: “It is humbling and challenging because we can see what we will lose and how much or how little we can do about...

Submitted on 12 Apr 2021 by:

The magnitude-6 earthquake that struck Java on Saturday, 10 April 2021, at approximately 2pm (local time) occurred at a depth of 82 kilometres (km), according to the United States Geological Survey. This earthquake was strongly felt in East Java and led to loss of life and property. The location of this earthquake is the main reason why it was felt so strongly.

The earthquake occurred about 60 km southwest of Malang, off the coast of Java, a region where the Indo-Australian plate dives under the Eurasian plate. In this region, the subducting plate experiences downward-pulling forces. It also experiences increasing pressure and temperature, which cause hydrous minerals to release water. These processes work together to cause the deeper part of the slab to break and...

Submitted on 10 Mar 2021 by:

Palm oil is indispensable to us but it is associated with environmental and social problems, such as land conflicts, deforestation, and haze. Does certifying palm oil help alleviate some of these problems?

A team led by Assistant Professor Janice Lee, a Principal Investigator at the Earth Observatory of Singapore, recently published a study in Environmental Research Letters presenting the impacts of palm oil certification on the environment and the development of Indonesia.

The team evaluated the outcomes from the Roundtable on Sustainable Palm Oil (RSPO), a non-profit organisation that developed a set of criteria for palm oil certification. While certification systems work to protect the...

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...

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