1996 Biak earthquake

Coordinates: 0°57′S 136°56′E / 0.95°S 136.94°E / -0.95; 136.94
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1996 Biak earthquake
1996 Biak earthquake is located in Papua (province)
1996 Biak earthquake
1996 Biak earthquake is located in Indonesia
1996 Biak earthquake
UTC time1996-02-17 05:59:30
ISC event947787
USGS-ANSSComCat
Local date17 February 1996 (1996-02-17)
Local time14:59:30 WIT (Indonesia Eastern Standard Time)
Magnitude8.2 Mw [1]
Depth20 km (12 mi) [1]
Epicenter0°57′S 136°56′E / 0.95°S 136.94°E / -0.95; 136.94 [1]
TypeMegathrust[2]
Total damage$US 4.2 million [3]
Max. intensityMMI IX (Violent)
Tsunami7.7 m (25 ft)
Casualties108 dead, 423 injured, 58 missing, 10,000 displaced

The 1996 Biak earthquake, or the Irian Jaya earthquake, occurred on 17 February at 14:59:30 local time near

Mercalli intensity of IX (Violent).[4] The run-up height of the generated tsunami reached 7.7 m (25 ft). The disaster left at least 108 people dead, 423 injured, and 58 missing.[5] It damaged or destroyed 5,043 houses which subsequently made another 10,000 homeless.[5] At Korim, 187 houses were destroyed.[6]
Various countries and organizations provided aid and relief in the aftermath of the earthquake.

Tectonic setting

Tectonic map of the New Guinea region with relative plate motion.

New Guinea lies within a very complex tectonic regime surrounded by microplates which accommodate the collision and oblique convergence between the Australian Plate and the Pacific Plate.[7][8] In the north, the Caroline Plate and North Bismarck Plate subduct underneath the Bird's Head Plate and the Woodlark Plate along the New Guinea Trench.[9][10][11] The earthquake occurred at the central portion of the trench. The western portion of New Guinea has parallel subduction zones to the north and south of it along a continuation of the Philippine Trench and a convergent boundary between the Bird's Head Plate and the Banda Sea Plate.[12][11] In western central New Guinea, the Maoke Plate has multiple boundaries with various plates.[13] At the far eastern portion of the island, the South Bismarck Plate interacts with the Woodlark Plate, as well as the Solomon Sea Plate subducting underneath the Woodlark Plate.[9][11] The largest on-land plate boundary in the region, however, is between the Woodlark Plate and the Australian Plate.[11] Though generally considered largely aseismic before this earthquake, this region of the New Guinea Trench may have experienced a similar large earthquake in 1914.[14]

Earthquake

Focal mechanisms indicate shallow-angle reverse faulting which is consistent with a subduction zone rupture. It ruptured an area 230 km (140 mi) long and 100 km (62 mi) wide along the New Guinea oceanic trench with an average slip of 4 m (13 ft). From the hypocenter, the rupture propagated 180 km (110 mi) to the west before propagating another 50 km (31 mi) east, ~15 seconds later. The largest slip was ~12 m (39 ft) near the hypocenter.[14] Large aftershocks struck the area, with various focal mechanisms. The mainshock may have triggered nearby seismic structures to activate. Aftershocks were most common in the areas with the highest slip from the mainshock.[14]

Tsunami

Teletsunami observations[15][16]
Location Recorded height (m)
Shionomisaki, Japan 0.96
Chichi
, Japan		 1.03
Tateyama, Japan 0.90
Shemya, USA 0.35
Adak, USA 0.10
Port Alberni, Canada 0.37
Winter Harbour, Canada 0.15
Crescent City, USA 0.18
Santa Monica, USA 0.05

At Madori, on the west coast of Biak, a run-up of 7.7 m (25 ft) was measured, while at Korem in northern Biak, waves were up to 5.4 m (18 ft). The tsunami also affected parts of nearby islands, including

Owi, and Pai, where waves of 4–7 m (13–23 ft) were measured.[6][17][18] Roughly five minutes after the shaking, nearby residents heard an extraordinarily loud sound, such as one from an airplane, which they understood as a signal that a large wave was approaching. The local coastal population fled for higher ground as result. This action is credited with saving many lives from the tsunami.[6]

The tsunami produced was larger than expected for the size and location of the earthquake. A localized submarine landslide was a plausible explanation for the strong waves in western Biak.[19] This is further supported by the west coast of Biak being struck by the tsunami first, despite facing away from the main tsunami source. This does not align with a traditional shallow earthquake rupture tsunami, which further lends credence to the theory of a submarine landslide in the area near Madori. Multiple landslides were reported in the area near the maximum run-up height.[20][6]

Aftermath

Domestic relief efforts

Immediately after the earthquake, the government of Indonesia provided rice to the affected.

First Lady of Indonesia contributed US$63,938 in cash, as well as 8,000 pieces of clothing.[23]

International relief efforts

The

USAID donated US$265,486 for housing (plastic sheeting, tents, blankets), US$10,000 to help with distributing relief as well as a two-member assessment team. Another US$10,000 was to distribute relief items.[23] The Association of Medical Doctors of Asia contributed a team of three doctors with supplies and tools to help treat the injured.[23]

See also

References

  1. ^ a b c ISC (2015), ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009), Version 2.0, International Seismological Centre, archived from the original on 25 November 2016, retrieved 15 February 2016
  2. doi:10.1029/1998JB000018, archived
    (PDF) from the original on 13 June 2010, retrieved 29 August 2010
  3. ^ USGS (4 September 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey, archived from the original on 17 July 2020, retrieved 8 November 2018
  4. ^ "Katalog Gempabumi Signifikan dan Dirasakan". bmkg.go.id. BMKG. Archived from the original on 25 July 2021. Retrieved 11 August 2021.
  5. ^ a b "Hari Ini dalam Sejarah: Gempa dan Tsunami Terjang Irian Jaya, 108 Orang Meninggal". Kompas (in Indonesian). 17 February 2021. Archived from the original on 4 August 2022. Retrieved 4 August 2022.
  6. ^
    doi:10.1029/97EO00128
    .
  7. ^ Taylor, M. A. J.; Dmowska, R.; Rice, J. R., Comparison of Coulomb Shear Stress Changes from the Feb. 17, 1996 Biak Mw = 8.2 Event and a Subsequent Seismic Inversion, archived from the original on 15 July 2010, retrieved 29 August 2010
  8. hdl:1885/104031
    .
  9. ^
    doi:10.1029/2003JB002481
    .
  10. ^ Tregoning, Paul. "Plate kinematics in the western Pacific derived from geodetic observations" (PDF). Australian National University. Archived (PDF) from the original on 15 June 2022. Retrieved 2 August 2022.
  11. ^
    S2CID 9127133
    .
  12. S2CID 131074367. Archived
    from the original on 13 September 2022. Retrieved 2 August 2022.
  13. S2CID 228963531
    .
  14. ^
    doi:10.1029/2001JB000796
  15. ^ "Tsunami Newsletter, Vol. XXVIII, No. 2, July 1996, 35 p." (PDF). International Tsunami Information Center. Archived (PDF) from the original on 5 August 2022. Retrieved 4 August 2022.
  16. S2CID 140181911. Archived
    from the original on 13 September 2022. Retrieved 5 August 2022.
  17. S2CID 245171123
    .
  18. ^ Prawiradisastra, Suryana; Santoso, Eko Widi (1997). "Identifikasi Gempa Biak 17 Pebruari 1996 sebagai Upaya Program Mitigasi Bencana". Alami: Jurnal Teknologi Reduksi Risiko Bencana (in Indonesian). 2 (3). Archived from the original on 13 September 2022. Retrieved 4 August 2022.
  19. doi:10.17014/ijog.v7i1.135. Archived
    from the original on 4 August 2022. Retrieved 2 August 2022.
  20. S2CID 129537661. Archived
    from the original on 13 September 2022. Retrieved 2 August 2022.
  21. ^ "Indonesia - Earthquake Information Report No.1". reliefweb. UN DHA. Archived from the original on 3 August 2022. Retrieved 3 August 2022.
  22. ^ "Indonesia - Earthquake Information Report No.2". reliefweb. UN DHA. Archived from the original on 3 August 2022. Retrieved 3 August 2022.
  23. ^ a b c d e f g "Indonesia - Earthquake Information Report No.3". reliefweb. UN DHA. Archived from the original on 3 August 2022. Retrieved 3 August 2022.

External links

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