Sumatra on EARTH Magazine

19th-century discovery now reveals modern human arrival in Sumatra

Thu, 14 Dec 2017 06:57:40 -0500

New research at Lida Ajer Cave in Sumatra, combined with data from human teeth found there in the 1880s, suggests humans were in Indonesia roughly 20,000 years earlier than previously thought. Credit: Julien Louys.

Modern humans began journeying out of Africa by at least 75,000 years ago, eventually expanding across the planet. Evidence of these early human travels, including fossils and artifacts, is typically spotty and difficult to find. But one such discovery more than a century ago has shed new light on the appearance of humans in Southeast Asia.

Dehydrated sediment layer made Sumatra quake stronger

Tue, 15 Aug 2017 14:25:42 -0400

Map showing the rupture zone of the magnitude-9.1 Sumatra quake in December 2004, as well as the tsunami inundation zone and locations where scientists pulled up sediment cores that are adding to the understanding of the massive quake. Credit: K. Cantner, AGI.

Subduction zones are notorious for unleashing great earthquakes and tsunamis, such as the 2004 magnitude-9.1 Sumatra quake that caused shaking and inundations that killed more than 250,000 people and left millions more homeless. However, despite the dangerous reputations of subduction zones, their hazards are still often underestimated. New research reveals how sediments in the Sumatra Trench may have contributed to producing an even bigger earthquake and tsunami than hazard forecasts had estimated.

Downgoing plate topography stopped 2005 Sumatra rupture

Fri, 01 Apr 2016 12:10:25 -0400

Earthquakes off the coast of Sumatra in 2004 and 2005 ruptured different neighboring segments of the subduction zone. A raised ridge between the segments may have blocked the ruptures from propagating simultaneously. Credit: K. Cantner, AGI.

In late March 2005, a magnitude-8.7 earthquake struck off the northwest coast of Sumatra, Indonesia, rupturing a portion of the Sunda Megathrust Fault and further terrorizing a region still reeling from the devastating 2004 Boxing Day earthquake and tsunami just three months prior. The March quake, however, could have been far larger than it was, according to new research. Scientists have identified a topographic barrier on the oceanic Indo-Australian Plate — which descends under the Sunda Plate in the Sumatra Subduction Zone — that may have stopped the 2005 rupture from propagating farther.

Sumatran strike-slip earthquakes challenge seismologists

Wed, 09 May 2012 14:35:04 -0400

Map showing the location of two large strike-slip earthquakes (red stars) off the west coast of Sumatra, Indonesia on April 11, 2012. Aftershocks (orange circles) of the strike-slip earthquakes are also indicated, as are prominent tectonic features including the Sunda megathrust fault (pink) and a series of north-south fractures (black) in the vicinity of the earthquakes. courtesy of Earth Observatory of Singapore

Events may shed light on regional tectonics, alter stress on nearby megathrust

Following the magnitude-8.6 earthquake that struck off the coast of Sumatra, Indonesia on April 11, chaos reigned in Banda Aceh, a provincial capital near Sumatra’s northern tip as residents scrambled to evacuate to higher ground ahead of a potential tsunami. Unlike in December 2004 when a deadly tsunami — triggered by the magnitude-9.1 Sumatra-Andaman earthquake — swept over the Sumatran coastline, though, no significant tsunamis made landfall on April 11 and only a handful of earthquake-related fatalities were reported.

Earthquake rocks Sumatra

Thu, 05 Jan 2012 06:41:58 -0500

A magnitude-7.6 earthquake rocked Sumatra, the westernmost island of Indonesia, on Wednesday. U.S. Geological Survey Earthquake Hazards Program

Updated on Oct. 1:

A second, magnitude-6.6 earthquake struck southern Sumatra, Indonesia, today at about 8:52 a.m. local time; this time, the epicenter was 215 kilometers southeast of Padang, West Sumatra. The death toll from both events has risen to at least 531 people.