2002 Sumatra earthquake

Tectonic setting

The island of Sumatra lies on the convergent plate boundary between the Indo-Australian plate and the Eurasian plate. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust, and near pure strike-slip faulting along the Great Sumatran fault. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797, 1833, 1861, 2004, 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935, 1984, 2000 and 2002.

Earthquake

The earthquake occurred as a result of shallow thrust faulting on the boundary between the subducting Australian Plate and the overriding Sunda Plate. while the International Seismological Centre and the National Centers for Environmental Information said that the earthquake had a magnitude of 7.2 and 7.6, respectively.

Its offshore epicenter was located 7 km north-northeast of Simeulue Regency, and 50 km northwest of the town of Sinabang. A rupture area of 65 km x 75 km was estimated, extending southwest to Simeulue, with a maximum slip of 1.123 m near the hypocenter; up to 0.982 m of slip was recorded at Simeulue. The observed source time function gives a 20 second duration for the earthquake, with the greatest phase of seismic moment release occurring almost 10 seconds after initiation. VI (Strong) at Tapaktuan and V (Moderate) at Meulaboh and Singkil in Aceh Province. including a 6.3 event at 09:46 UTC on 2 November, which had a maximum MMI of VII.

The rupture area of the 2002 earthquake lies at the boundary between the rupture areas of the 2004 and 2005 earthquakes, as determined by the uplift patterns of coral microatolls. From its proximity to the epicenter of the 2004 earthquake, it is regarded as a foreshock of that event. Microatolls around Simeulue show evidence of uplift as a result of the 2002 event, distinct from the uplift caused by the 2004 event. Waveforms from this earthquake have been used to model the propagation of Rayleigh waves during the 2004 earthquake, using an empirical Green's function analysis.

Damage and casualties

The earthquake killed three people, injured 65 others and damaged 994 homes, Dozens of homes and shops were completely destroyed.

References

References

1. {{cite anss. M 7.4 - 50 km NW of Sinabang, Indonesia. 2002. usp000bfuz
2. Natawidjaja, D. H.. (2006). "Source parameters of the great Sumatran megathrust earthquakes of 1797 and 1833 inferred from coral microatolls". Journal of Geophysical Research.
3. (2 November 2002). "Earthquake off Indonesia's Sumatra injures 40". [[Reuters]].
4. b 4.7 [[foreshock]]s to the north on 18 and 31 October, respectively.{{cite anss. M 4.7 - 88 km NNW of Sinabang, Indonesia. 2002. usp000bet2
5. {{cite anss. M 4.7 - 93 km NNW of Sinabang, Indonesia. 2002. usp000bfqc
6. {{cite anss. M 6.3 - 52 km N of Sinabang, Indonesia. 2002. usp000bfwd
7. Biggs, J.. (2009). "The 2007 Pisco, Peru, earthquake (M8.0): seismology and geodesy". Geophysical Journal International.
8. Sieh, K.. "The Sunda megathrust: past, present and future".
9. Vallée, M.. (2007). "Rupture Properties of the Giant Sumatra Earthquake Imaged by Empirical Green's Function Analysis". Bulletin of the Seismological Society of America.
10. (2 November 2002). "Indonesia hit by quake". [[BBC News]].
11. ISC. (2022). "ISC-GEM Global Instrumental Earthquake Catalogue (1904–2018)". [[International Seismological Centre]].
12. National Geophysical Data Center / World Data Service (NGDC/WDS). (1972). "Significant Earthquake Database". [[National Geophysical Data Center]], [[National Oceanic and Atmospheric Administration.