Earth Observatory Blog

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 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 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 23 Mar 2017 by:

The tectonically sleepy, yet very populated island of Bali was shaken on Wednesday morning (22 March 2017) by a magnitude-5.5 earthquake. Located 2 kilometres (km) northeast of Banjar Pasekan in southeastern Bali, the morning quake shook the area. But, because of its 118 km-depth, it did not cause major damage or any casualties.

Director of the Earth Observatory of Singapore, Professor Kerry Sieh, who has studied the mega-thrust fault off of the western side of Sumatra and down through Java and Bali, suggests that yesterday’s moderate earthquake is a reminder to us that even though the area has been dormant for the past several hundred years, it has the potential to release a large earthquake, or even a series of large quakes, of about magnitude-8.5 to 9.0 in the...