1990 Bohol Sea earthquake

The 1990 Bohol earthquake occurred on February 8, 1990 at 15:15:32 (UTC +8) which had a magnitude of 6.8 on the moment magnitude scale and VII (Very strong) on the Modified Mercalli intensity scale.[2] Most of the damage was observed in the province of Bohol.[3] A tsunami hit the southeastern coastline of Bohol and the island of Camiguin.[4] There were 6 deaths, over 200 injuries and an estimated ₱157 million ($7 million) in total damages reported.

1990 Bohol Sea earthquake
UTC time1990-02-08 07:15:32
ISC event377912
 377915
USGS-ANSSComCat
 ComCat
Local dateFebruary 8, 1990
Local time15:15:32 PST
Magnitude6.8 Mw
Depth25.9 kilometers
Epicenter9.755°N 124.694°E25.9
FaultBohol Fault System
TypeDip-slip
Areas affectedBohol, Cebu, Camiguin, Leyte, Negros Occidental, Negros Oriental, Cagayan de Oro, Siquijor
Total damage₱157 million ($7 million)
Max. intensityPEIS – VII (Destructive)
Peak acceleration1.50 g
TsunamiYes, 2 meter waves observed in Camiguin island
LandslidesYes
Aftershocks6.6 Mw[1]
Casualties6 fatalities, 200+ injuries

Twenty-three years later, a similar quake occurred and wreaked havoc.[5]

Background

The Philippines is usually prone to earthquakes due to its location within the Pacific Ring of Fire, where most of the world's seismological events occur. However, the Central Visayas region is not particularly known for having frequent seismic activity. But if these do happen, they are surprisingly violent and information is sparse.

Earthquake

The epicentre of the quake was located 17 km southeast of Tagbilaran City and was due to the rupture of an unknown fault line offshore Bohol island. It had a magnitude of 6.8 and was recorded as an Intensity VII by the Philippine Institute of Volcanology and Seismology but lowered down to Intensity VI by the United States Geological Survey on the Rossi–Forel scale and the Mercalli scale respectively.[6][7]

Tsunami

The rupture from the unknown fault that caused tsunami waves reported as high as 2 meters hitting the surrounding islands nearby. There were no damage reported from the waves.[8][4]

Casualties and damage

Damage was mostly sustained by the Eastern and Southeastern Coastline of Bohol most of which were due to poorly built infrastructure that couldn't stand such strong movement. Estimates say that about 3,000 units of houses and other structures as well as 182 of which were totally demolished such as a bridge connecting the towns of Jagna and Duero and roads to the town of Anda. Landslides and Fissures have also been observed in particular places near the epicenter. The total cost is estimated at ₱157 million ($7 million).

There were six (6) confirmed deaths from the quake and at least 200 injuries. A further 46,000 were displaced and 7,000 homeless.[6]

See also

References
  1. "M 6.6 - 6 km ESE of Bacong, Philippines". earthquake.usgs.gov. USGS–ANSS. Retrieved 22 August 2021.
  2. "M 6.8 - 13 km E of Bacong, Philippines". earthquake.usgs.gov. Archived from the original on 2021-08-09. Retrieved 2021-08-21.
  3. "Philippine Earthquake February 8, 1990" (PDF). EERI Newsletter.
  4. Besana, G. M.; Daligdig, J. A.; Abigania, M. T.; Talisic, J. E.; Evangelista, N. (2004-12-01). "Insights on the 1990 Bohol Tsunamigenic Earthquake, Bohol Island, Philippines". AGU Fall Meeting Abstracts. 11: S11A–1004.
  5. "Deadly Philippine quake hits Bohol and Cebu". BBC News. 2013-10-15. Retrieved 2021-08-21.
  6. "February 08, 1990 Earthquake in Bohol Province. PHIVOLCS". Archived from the original on 2021-08-13.
  7. "M 6.8 - 13 km E of Bacong, Philippines". earthquake.usgs.gov. Archived from the original on 2021-08-09. Retrieved 2021-08-22.
  8. "The 1990 Bohol earthquake: Tsunami observations and effects at Bohol Island, Philippines". Science of Tsunami Hazards.

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