The 1990 Bohol earthquake occurred on February 8, 1990 at 15:15:32 (UTC +8) which had a magnitude of 6.8 . The earthquake had a moderate depth of 25.9 km (16 mi). Most of the damage was observed in the province of

Bohol Bohol (), officially the Province of Bohol ( ceb, Lalawigan sa Bohol; tl, Lalawigan ng Bohol), is an island province of the Philippines located in the Central Visayas Regions of the Philippines, region, consisting of the island itself and 75 m ...

. A

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

hit the southeastern coastline of Bohol and the island of

Camiguin Camiguin, officially the Province of Camiguin ( ceb, Probinsya sa Camiguin; tl, Lalawigan ng Camiguin; Kamigin: ''Probinsya ta Kamigin''), is an island province in the Philippines located in the Bohol Sea, about off the northern coast of Min ...

. There were 6 deaths, over 200 injuries and an estimated

₱ The Philippine peso sign (₱) is the currency symbol used for the Philippine peso, the official currency of the Philippines. The symbol resembles a Roman letter P with two horizontal strokes. It differs from the currency symbol used for the pe ...

157 million ( $7 million) in total damage reported. Twenty-three years later, a much more devastating 7.2 M_w under the same fault system would strike the island killing 222 individuals.

Tectonic Setting

The Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

is usually prone to earthquakes due to its location within the

Pacific Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many Types of volcanic eruptions, volcanic eruptions and ...

, where most of the world's seismological events occur. The Bohol Sea is home to segments of the

Philippine Fault System The Philippine Fault System is a major inter-related system of geological faults throughout the whole of the Philippine Archipelago, primarily caused by tectonic forces compressing the Philippines into what geophysicists call the Philippine Mobil ...

, a system of fault line extending from the Northwestern province of

Ilocos Sur Ilocos Sur, officially the Province of Ilocos Sur ( ilo, Probinsia ti Ilocos Sur; tl, Lalawigan ng Ilocos Sur), is a province in the Philippines located in the Ilocos Region in Luzon. Located on the mouth of the Mestizo River is the capital o ...

, transversing through

Quezon province Quezon, officially the Province of Quezon ( tl, Lalawigan ng Quezon), is a province in the Philippines located in the Calabarzon region on Luzon. Kalilayan was the first known name of the province. It was later renamed Tayabas. In honor of the ...

Masbate Island Masbate Island is the largest of three major islands of Masbate Province in the Philippines. The other two major islands are Ticao Island and Burias (island), Burias Island. It is the 11th-largest island in both area and population in the Philip ...

and the

Eastern Visayas region Eastern Visayas ( war, Sinirangan Kabisay-an; ceb, Sidlakang Kabisay-an; tl, Silangang Kabisayaan or ''Silangang Visayas'') is an administrative region in the Philippines, designated as Region VIII. It consists of three main islands, Samar, ...

, and ending at the end of

Davao Gulf Davao Gulf is a gulf situated in the southeastern portion of Mindanao in the Philippines. It has an area of or about 520,000 hectares. Davao Gulf cuts into the island of Mindanao from the Philippine Sea. It is surrounded by all five provinces in ...

. The fault that had ruptured suggested a northeast-southwest trending nodal plane. However, overlaying layers of milocene dated limestone suggested that the fault was inactive for numerous years.

Earthquake

The epicentre of the quake was located 17 km southeast of

Tagbilaran City Tagbilaran, officially the City of Tagbilaran ( ceb, Dakbayan sa Tagbilaran), is a 3rd class component city and capital of the province of Bohol, Philippines. According to the 2020 census, it has a population of 104,976 people. Encompassing a la ...

and was due to the rupture of an unknown normal fault line offshore Bohol island. The ruptures have caused dipping in a southeastern direction. It recorded a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

of 6.7–6.8, measuring an Intensity of VII (''Destructive'') on the PHIVOLCS Intensity Scale, as well as a maximum intensity of VIII (Damaging tremor) on the Rossi-Forrel scale recorded in Tagbilaran City. Approximately 30 minutes after the mainshock, an aftershock with a close magnitude of 6.6 occurred near the same area, with a different slip pattern, directing in a northwestward direction. The said aftershock caused some damage and further worsened the conditions from the already affected buildings.

Tsunami

The rupture from the unknown fault that caused

waves reported as high as 2 meters hitting the surrounding islands nearby. There were no damage reported from the waves.

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 could not 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 Jagna, officially the Municipality of Jagna ( ceb, Munisipalidad sa Jagna; tgl, Bayan ng Jagna), is a 3rd class municipality in the province of Bohol, Philippines. According to the 2020 census, it has a population of 35,832 people. Jagna is lo ...

and

Duero The Douro (, , ; es, Duero ; la, Durius) is the highest-flow river of the Iberian Peninsula. It rises near Duruelo de la Sierra in Soria Province, central Spain, meanders south briefly then flows generally west through the north-west part of ...

and roads to the town of

Anda Anda or ANDA may refer to: Places China *Anda, Heilongjiang, a city in Heilongjiang, China *Anda railway station, a railway station in Anda, China Iran *Anda, Iran, a village in Fars Province, Iran Norway *Anda, Norway, an island in Øksnes mun ...

Landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

Fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

s, multiple

Mud Volcanoes A mud volcano or mud dome is a landform created by the eruption of mud or slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true igneous volcanoes as they do not produce lava ...

, and a drastic increase of sea levels were observed in particular places near the epicenter. The total cost is estimated at ₱157 million ($7 million). There were 6 confirmed deaths from the quake and at least 200 injuries. A further 46,000 were displaced and 7,000 homeless.

References

{{DEFAULTSORT:1990 Bohol Sea earthquake Bohol Sea earthquake Bohol Sea Earthquakes in the Philippines Bohol Sea earthquake History of Bohol Bohol Sea earthquake 1990 disasters in the Philippines

Tectonic Setting

Earthquake

Tsunami

Casualties and damage

See also

References