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

volcanic island Geologically, a volcanic island is an island of volcanic origin. The term high island 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 (; ), 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, the most populous town in the province. To the east lies ...

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

in the

Mindanao Mindanao ( ) is the List of islands of the Philippines, second-largest island in the Philippines, after Luzon, and List of islands by population, seventh-most populous island in the world. Located in the southern region of the archipelago, the ...

region, southern

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

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

fumarolic A fumarole (or fumerole) is a vent in the surface of the Earth or another 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 ...

volcano A volcano is commonly defined as a vent or fissure 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 oft ...

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. The island is also located about north of Marore Island, one of the outlying islands of Indonesia. Politically, the group is organized under the Municipality of Sarangani of Davao Occidental since 1978, having previously been part of

Jose Abad Santos Jose is the English transliteration of the Hebrew and Aramaic name ''Yose'', which is etymologically linked to ''Yosef'' or Joseph. Given name Mishnaic and Talmudic periods *Jose ben Abin *Jose ben Akabya *Jose the Galilean *Jose ben Halafta *Jo ...

. Mabila on Balut Island is administrative and commercial center of the town. Balut is subdivided into 10

barangay The barangay (; abbreviated as Brgy. or Bgy.), historically referred to as ''barrio'', is the smallest Administrative divisions of the Philippines, administrative division in the Philippines. Named after the Precolonial barangay, precolonial po ...

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 a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level ...

. 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 mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

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'' (from Spanish '' población'', meaning "population"), sometimes abbreviated as Pob., is a term used in the Philippines to refer to the administrative center, downtown, old town, or commercial area of a city or municipality. It ...

'' 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 The Philippine Institute of Volcanology and Seismology (PHIVOLCS, ; ) is a Philippine national institution dedicated to provide information on the activities of volcanoes, earthquakes, and tsunamis, as well as other specialized information and ...

as a potentially active

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

with

solfataric A fumarole (or fumerole) is a vent in the surface of the Earth or another 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 volcan ...

activity. Hot springs and thermally altered grounds with temperatures of are located at the west and Southwest 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 aphanite, 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 planetary surface, surface of a terrestrial ...

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 predomina ...

. Balut is part of the Central Mindanao Arc, an area of frequent

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

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 tectonic belt of volcanoes and earthquakes. It is about long and up to about wide, and surrounds most of the Pa ...

. 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 Polaris is a star in the northern circumpolar constellation of Ursa Minor. It is designated α Ursae Minoris (Latinisation of names, Latinized to ''Alpha Ursae Minoris'') and is commonly called the North Star or Pole Star. With an ...

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 both ...

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 lightweight x86-64 Linux distribution targeted at experienced Linux users and delivered by a tar.gz-based package system with BSD-style initscripts. It is not based on any other Linux distribution. It also utilizes a ports system to ...

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 (N), south (S), east (E), and west (W). The corresponding azimuths (clockwise horizontal angle from north) are 0°, 90°, 180°, and 270°. The four o ...

. Being near the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

, 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 The Philippine Atmospheric, Geophysical and Astronomical Services Administration (, abbreviated as PAGASA , which means "hope" as in the Tagalog language, Tagalog word ''pag-asa'') is the National Meteorological and Hydrological Services (NMHS ...

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 Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...

. 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 The Bakunawa, also called the Philippine moon-eating dragon, the Philippine moon dragon, moon dragon, or the moon-eating dragon, is a serpent, that looks like a Dragon in Philippine mythology. It is believed to be the cause of eclipses, earthqu ...

, that devours the sun.