An earthquake with a magnitude of 6.7 that occurred on May 14, 2021 was an unusual earthquake, which was centered between the subduction zone and the divergent zone, otherwise known as an intraplate earthquake or outer rise earthquake. The cause of the outer rise earthquake is the tectonic stress that acts on the earthquake source of the outer rise of the extension stress or pull, the earthquake in the outer rise zone has a normal fault source mechanism. The mechanism of the outer rise earthquake source could also be due to a shear fault (transform) as happened in Aceh on April 11, 2012. Twin earthquakes with a strength of 8.5 on the Richter scale and 8.1 on the Richter scale, followed by a small tsunami as high as 1 meter in Nias, 80 cm in Meulaboh, and 6 cm in Sabang.
Earthquake records outside the subduction zone include the 9 June 2016 earthquake south of Bali with a magnitude of M6.0, 15 July 2016 earthquake in the south of West Java M5.1 which shook the southern coast of West Java, 23 July 2016, the Bengkulu and Lampung earthquake with a M 5 magnitude, 4 that rocked the coasts of Bengkulu to Lampung and March 19, 2020, the southern Bali earthquake with a magnitude of M6.5 was felt throughout Bali and Lombok.
The magnitude and mechanism of the outer rise earthquake source can trigger a tsunami, this has been recorded in Indonesia in various regions, including: (1) On 11 September 1921 an earthquake in southern Java measuring M7.5 occurred which triggered a tsunami, (2) On 19 August 1977 earthquake south of Sumbawa measuring M8.3 triggered a destructive tsunami south of Sumbawa.
Geophysical Engineering ITS in collaboration with Masyarakat Geologi Tata Lingkungan (Mageti) presents WEBINAR “Memahami Gempa ‘Outer Rise’ Busur Sunda, dari Sumatra sampai Sumba”, with invited resource speakers:
As a respondent:
and the moderator:
This event will be held virtually on:
The presentation of resource speakers could be accessed through the following link:
Let’s join the event and get the e-certificate
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