Magnitude 7.3 - NICOBAR ISLANDS, INDIA REGION
2005 July 24 15:42:06 UTC
- This event has been reviewed by a seismologist.
|Depth||16 km (9.9 miles) set by location program|
|Region||NICOBAR ISLANDS, INDIA REGION|
135 km (85 miles) W of Misha, Nicobar Islands, India
420 km (260 miles) S of Port Blair, Andaman Islands, India
1110 km (690 miles) SW of BANGKOK, Thailand
2775 km (1720 miles) SE of NEW DELHI, Delhi, India
|Location Uncertainty||horizontal +/- 4.9 km (3.0 miles); depth fixed by location program|
|Parameters||NST=259, Nph=259, Dmin=982.9 km, Rmss=0.91 sec, Gp= 32°,|
M-type=teleseismic moment magnitude (Mw), Version=S
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Some buildings damaged in the Andaman and Nicobar Islands. Felt (V) on Car Nicobar, Katchal and Nancowry. Also felt (V) at Campbell Bay, Great Nicobar and Port Blair, South Andaman Island. Felt (IV) at Chennai; (III) at Srikakulam, Visakhapatnam, Vizianagaram and other coastal areas of Andhra Pradesh and at Dum Dum and Garia, West Bengal, India. Felt at Mamallapuram, India. Felt (IV) in Aceh Province, Indonesia. Felt (III) at Colombo, Matale and Kandy, Sri Lanka. Felt at Peraliya and Sri Jayawardenepura Kotte, Sri Lanka. Also felt at Male, Maldives and on Phuket, Thailand.
This earthquake occurred near the western boundary of the aftershock zone of the devastating Sumatra-Andaman Islands earthquake of December 26, 2004. The aftershock zone of the December 26th earthquake continues to be active and forms a crescent-shaped region extending about 1200 km north of Sumatra, Indonesia. The recent event was a strike-slip earthquake, probably in the India plate below its shallowly dipping boundary with the Burma plate. The earthquake resulted from horizontal displacement of the ground across a nearly vertical fault plane. This is unlike the thrust-fault motion that produced the December 26th earthquake and that occurred on the interface of the eastward-subducting India plate and the overriding Burma plate. The recent event therefore occurred on a different fault than the fault that caused the Great Sumatra-Andaman Islands earthquake. However, the two earthquakes are almost certainly related. A great earthquake can trigger earthquake activity on faults that are distinct from the main-shock fault plane, and separated from it by tens or even hundreds of kilometers. A magnitude 7.2 earthquake is considered a major earthquake, but the size of this recent earthquake pales in comparison to the December 26th earthquake. A 7.2 strike-slip earthquake typically ruptures a 15 km by 80 km patch along a fault, whereas the December 26, 2004 earthquake ruptured a patch of fault about 1200 km long and 200 km wide.
Scientific & Technical Information
The earthquake locations and magnitudes cited in NOAA tsunami statements and bulletins are preliminary and are superseded by USGS locations and magnitudes computed using more extensive data sets.
NOAA Tsunami Bulletins for this Earthquake
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- Pacific Tsunami Warning Center
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The earthquake locations and magnitudes cited in these bulletins are very preliminary, and may disagree with the more accurate USGS locations and magnitudes computed using more extensive data sets.
General Tsunami Information
- Preliminary Earthquake Report
- U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver