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last updated: 04/11/12 11:22.24 (PDT)

On Wednesday April 11 2012 at 1:38 AM (PDT) the USArray seismic network recorded an earthquake (preliminary Mw 8.6) located off the west coast of Sumatra, Indonesia.

Initial source parameters for this tremor are indicated below. The epicentral distance (i.e. distance separating the epicenter and the closest station in the recording network, TOLK) for the USArray is 10841 km (97.49 degrees).

If you felt the quake, the USGS would like to know. Please add your comments to the USGS page "Did you feel it?".


Global map view
Solution Parameters
Local Date:Wednesday April 11, 2012
Local Time: 1:38 AM PST
Universal Time:04/11/12 (102) 08:38.38 UTC
Magnitude:8.6 Mw
Depth:33 km

Proximity to Population Centers

  • 434 km (269 miles) SW of Banda Aceh, Sumatra, Indonesia
  • 550 km (341 miles) SW of Lhokseumawe, Sumatra, Indonesia
  • 963 km (598 miles) W of Kuala Lumpur, Malaysia
  • 1797 km (1116 miles) WNW of Jakarta, Java, Indonesia


Mercator projection regional view

The red star denotes the earthquake epicenter. Significant aftershocks are orange stars. Triangle symbols are active stations at the time of the earthquake in the USArray (excluding ANSS backbone stations and GSN stations, which are represented by a diamond symbol) and colored by network. Blue lines are major rivers. Thin black lines are state boundaries and thick black lines are national boundaries.

Regional map view
Network Legend
 Transportable Array (TA)
 UC San Diego (AZ)
 CalTech (CI)
 ANSS backbone stations (US)
 Global Seismograph Network (IU)
 Lamont-Doherty Coop Seismic Network (LD)
 POLARIS Network (PO)

Regional satellite view

The red marker denotes the earthquake epicenter. Significant aftershocks are orange stars.

Detailed terrain view

The red marker denotes the earthquake epicenter.


You may view plots showing this event as recorded by USArray instruments:

3 components recorded by TOLK, the closest USArray station to the event:

Latest monthly deployment map

Every arrival station waveforms

View waveforms from any station* that recorded arrivals for the event by entering the station code below (e.g. 109C) and clicking the 'View waveforms' button:

* – If waveforms are filtered, the filter type is listed on the image

News links

Tsunami information

Search the internet

To search the internet for more information about this event, click on the button below:

Search for this event using Goggle.com

Current seismic activity measured by USArray

Click the link below to observe an interactive map of earthquakes recorded by the USArray deployment:

Further information

Learn more about the Array Network Facility (ANF) component of USArray, the USArray experiment, the EarthScope project, and the Incorporated Research Institutions for Seismology (IRIS).

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