Balut Island, also known as Malulong, is a potentially active

volcanic island Geologically, a high island or volcanic island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed ...

south of the tip of

Davao Occidental Davao Occidental ( Cebuano: ''Kasadpang Dabaw''; Filipino: ''Kanlurang Davao''), officially the Province of Davao Occidental, is a province in the Philippines located in the Davao Region in Mindanao. Its capital is the municipality of Malita. To ...

province A province is almost always an administrative division within a country or state. The term derives from the ancient Roman ''provincia'', which was the major territorial and administrative unit of the Roman Empire's territorial possessions out ...

in the

Mindanao Mindanao ( ) ( Jawi: مينداناو) is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of ...

region, southern

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 ...

. At the center of the island is Balut Volcano, a

fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volc ...

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

with no historical eruptions.

Description

The island is located about from mainland

, separated by the Sarangani Strait. Balut, Sarangani and Olanivan islands make up the Sarangani Islands group. Politically, the group is organised under the Municipality of Sarangani of Davao Occidental. Mabila on Balut Island is administrative and commercial center of the town. Balut is subdivided into 8

barangay A barangay (; abbreviated as Brgy. or Bgy.), historically referred to as barrio (abbreviated as Bo.), is the smallest administrative division in the Philippines and is the native Filipino term for a village, district, or ward. In metropolita ...

Topography

Balut Island, the westernmost of the Sarangani Islands, is the larger, higher, and better cultivated than Sarangani Island. In the center of the island is Balut Volcano, which is fumarolic on occasion. Balut Island rises to about from the seabed with the highest elevation at

above mean sea level Height above mean sea level is a measure of the vertical distance ( height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as '' orthometric heights''. Th ...

. Base diameter of the island is . If seen from the northwest, it appears between two peaks. Northeast is another peak of Balut, southwest of the peak is the Langab volcano. In the southeast part of the island is Ten Seventy Hill with an elevation of .

Coastline

The north and east coasts are bordered by a reef, which in some places extends out over 1 mile, while on the south and west sides the fringing reef does not extend out to any distance. Off the southwest point is a rock island called Manamil Island with an elevation of . Lajan Point, the northeast point of the island, is low and covered by

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

s.Bureau of Insular Affairs (1902).
"A Pronouncing Gazetteer and geographical Dictionary of the Philippine Islands"
p.325. Washington Government Printing Office. South of the Lajan Point is Mabila, which is the ''

poblacion ''Poblacion'' (literally "town" or "settlement" in Spanish; ) is the common term used for the administrative center, central, downtown, old town or central business district area of a Philippine city or municipality, which may take up th ...

'' or town center of the Municipality of Sarangani. The Port of Mabila is the main port of entry to the island and the gateway to the rest of the municipality.(2010-12-04)
"PPA devolves Mabila Port to Sarangani LGU"
Philippine Information Agency.

Classification

Balut is classified by Philippine Institute of Volcanology and Seismology as a potentially active

stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and peri ...

with

solfataric A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

activity. Hot springs and thermally altered grounds with temperatures of are located at the west and Ssouthwest basal slopes of Balut Volcano. Temperature at the Palabuno Hot Spring is ."Balut"
Philippine Institute of Volcanology and Seismology. Retrieved on 2013-11-04.

Geology

Rock type on the volcano is predominantly

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

and

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...

. Balut is part of the

Central Mindanao Arc Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

, an area of frequent

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

s and volcanic activity. All volcanoes in the Philippines are part of 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 volcanic eruptions and earthquakes occur. The Ring o ...

. Like most volcanoes in southern Philippines, Balut Volcano is not studied much scientifically.

Volcanic activity

There are no recorded historical eruptions on the island. The January 4, 1641 eruption that enveloped most of

in darkness was falsely attributed to Balut Volcano, as well as other volcanoes in the Philippines. Later studies showed that the eruption was of Mount Parker, NW of Balut Island.

Astronomy

Being among the southernmost islands in the Philippines, it is possible to see both Polaris and the

Magellanic Clouds The Magellanic Clouds (''Magellanic system'' or ''Nubeculae Magellani'') are two irregular dwarf galaxies in the southern celestial hemisphere. Orbiting the Milky Way galaxy, these satellite galaxies are members of the Local Group. Because bo ...

from this area. Polaris is very low in the northern sky at about 5° altitude (about a thumb's length with the arm outstretched). The

Southern Cross Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

is also visible, and its vertical bar points almost directly at the South

cardinal point The four cardinal directions, or cardinal points, are the four main compass directions: north, east, south, and west, commonly denoted by their initials N, E, S, and W respectively. Relative to north, the directions east, south, and west are at ...

. Being near the equator, the sun is often very high in the sky. At a latitude of 5° 24', the sun passes directly overhead at noontime on or about April 3 and September 8 of each year, causing zero-length shadows. This phenomenon is not possible in high-latitude areas. Astronomers from

PAGASA Pagasa may refer to: * ''Pagasa'' (genus), an insect genus in the family Nabidae * PAGASA, an acronym for the Philippine Atmospheric, Geophysical and Astronomical Services Administration *"May Pagasa", a pen-name of José Rizal José Prot ...

set up on the island to observe the December 26, 2019 Annular Solar Eclipse. Balut Island, Sarangani Island, and Olanivan Island are the only places in the Philippines where the annularity was visible. Other parts of the Philippines only experienced a

partial solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six mon ...

. The eclipse had a magnitude of 97.2% in Balut Island, 97.1% in Sarangani Island, and 96.8% in Olanivan Island. According to local folklore, eclipses are caused by a large, celestial dragon called the Bakunawa, that devours the sun.