Mw 8.6 earthquake in Sumatra on March 28th, 2005 at 16:09 UTC

On March 28, at 16:09 UTC an earthquake with a preliminary magnitude of 8.6 struck Northern Sumatra. A magnitude 8.6 earthquake generates a rupture length of typically 500 kilometers and a displacement of several meters. Although it is a massive earthquake, the energy released is 10-15 times smaller than during the December 26th, 2004 event.

The epicentre is located approximately 200km SE of the December 26th 2004 epicentre. This event has generated a moderate tsunami much less destructive than the one generated by the December 26th event. Locally, wave have been estimated up to 4-5 meters and amplitude up to 2m have been recorded. In the Indian Ocean, amplitudes have been measured up to 50 cm. The aftershock activity is expected to last several weeks.

Waves measuring a maximum height of 2.3 meters (7.6 feet) were recorded in seas near Kirinda in southern Sri Lanka. Smaller waves up to 0.5 meters (1.65 feet) tall also brushed the coastline in the capital Colombo on the west coast of the island. The waves were recorded at both locations approximately three hours after the earthquake.

EMSC Location

Complementary documents

Understanding the potency of Giant Thrust Earthquake along Sumatra Subduction zone: The Effect of SuddenStress/Strain Loading (by Wahyu Triyoso ; Geophysics & Met. Dept ; FIKTM-ITB Bandung-Indonesia)
Understanding After Effect Along West Coast of Northern Sumatra: Tracing The Tail of Giant Thrust Earthquake After Effect (by Wahyu Triyoso ; Geophysics & Met. Dept ; FIKTM-ITB Bandung-Indonesia)
Source rupture process (preliminary results) (by Mourad Bezzeghoud, Evora University, Portugal)
Source analysis (by Martin Vallée, Géosciences Azur, IRD, Nice, France, vallee@geoazur.unice.fr)

Since 28/03/2005 16:09 UTC	Since 26/12/2004
New pattern in aftershocks distribution on April 10th ! The seismicity moved 400 km to the South-East Aftershocks Distribution since 28/03/2005	Aftershocks Distribution since 26/12/2004
Harvard Moment Tensors (since 28/03/2005)	Harvard Moment Tensors (From 26/12/2004 to 28/03/2005)
USGS Moment Tensors (since 28/03/2005)	USGS Moment Tensors (From 26/12/2004 to 28/03/2005)