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Mount Natib is a dormant
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 pe ...
and
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber i ...
complex in the
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 outsi ...
of
Bataan Bataan (), officially the Province of Bataan ( fil, Lalawigan ng Bataan ), is a province in the Central Luzon region of the Philippines. Its capital is the city of Balanga while Mariveles is the largest town in the province. Occupying the enti ...
on western
Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, a ...
Island of the Philippines. The volcano complex occupies the northern portion of the Bataan Peninsula. The mountain and adjacent surrounding is a
protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...
first declared as the
Bataan National Park Bataan National Park is a protected area of the Philippines located in the mountainous interior of Bataan province in the Central Luzon Region. The park straddles the northern half of Bataan Peninsula near its border with Subic Bay Freeport Zone. ...
in 1945.Mt. Natib"
. Bataan...Raging Peninsula. Retrieved on 2012-02-21.


Physical features

Mount Natib is a
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 pe ...
type of volcano topped by a acorn-shaped Natib
Caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber i ...
that is open to the northwest. East of its caldera is the smaller wide Pasukulan Caldera. The highest peak of Mount Natib has an elevation of
asl American Sign Language (ASL) is a natural language that serves as the predominant sign language of Deaf communities in the United States of America and most of Anglophone Canada. ASL is a complete and organized visual language that is express ...
and is at the point of convergence of the two calderas. The caldera complex has an overall base diameter of .


Volcanic activity

There are no historical eruptions within the Natib caldera complex. Studies in 1991 (Panum and Rayem) indicate that the last eruptive activity was probably Holocene to upper
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
. An earlier study in 1971 (Ebasco Services) dated the eruptive products between 69,000 +/- 27,000 years old. A recent study by Dr. Kevin Rodolfo of the Department of Earth and Environmental Sciences at the
University of Illinois at Chicago The University of Illinois Chicago (UIC) is a public research university in Chicago, Illinois. Its campus is in the Near West Side community area, adjacent to the Chicago Loop. The second campus established under the University of Illinoi ...
, had Mount Natib's latest eruption between 11,000 and 18,000 years ago after studying a prehistoric
pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
from the volcano that entered
Subic Bay Subic Bay is a bay on the west coast of the island of Luzon in the Philippines, about northwest of Manila Bay. An extension of the South China Sea, its shores were formerly the site of a major United States Navy facility, U.S. Naval Base Su ...
in
Zambales Zambales, officially the Province of Zambales ( fil, Lalawigan ng Zambales; ilo, Probinsia ti Zambales; Pangasinan: ''Luyag/Probinsia na Zambales''; xsb, Probinsya nin Zambales), is a province in the Philippines located in the Central Luzon r ...
province. Current activity on Natib is through five thermal areas. The
hot spring A hot spring, hydrothermal spring, or geothermal spring is a Spring (hydrology), spring produced by the emergence of Geothermal (geology), geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow ...
s in the Natib
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber i ...
are Asin, Mamot, Tigulangin, Uyong, and Paipit springs. The hot springs have temperatures ranging from 30-56 °C, with low flows, and a neutral to slightly alkaline water discharge. The
Philippine Institute of Volcanology and Seismology The Philippine Institute of Volcanology and Seismology (PHIVOLCS, ; tl, Surian ng Pilipinas sa Bulkanolohiya at Sismolohiya) is a Philippine national institution dedicated to provide information on the activities of volcanoes, earthquakes, and ...
(PHIVOLCS) lists Mount Natib as a potentially active volcano."Natib"
. Philippine Institute of Volcanology and Seismology. Retrieved on 2012-02-21.


Geology

The rocks found on Natib are predominantly
biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumi ...
,
hornblende Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic roc ...
, andesite, trending to
dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...
flows and dacitic tuffs, which are similar to Mount Mariveles, the southern half of the Bataan Peninsula. Natib is part of the Western Bataan Lineament
volcanic belt A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature () where magma is created by partial melting ...
, which includes the active Mount Pinatubo."Pinatubo Volcano"
. Philippine Institute of Volcanology and Seismology. Retrieved on 2012-02-21.


See also

*
List of active volcanoes in the Philippines This is a list of active volcanoes in the Philippines, as categorized by the Philippine Institute of Volcanology and Seismology (PHIVOLCS). Volcanoes in the country have erupted within the last 600 years, with accounts of these eruptions document ...
*
List of potentially active volcanoes in the Philippines This is a list of potentially active volcanoes in the Philippines, as classified by the Philippine Institute of Volcanology and Seismology. List See also * List of active volcanoes in the Philippines * List of inactive volcanoes in th ...
*
List of inactive volcanoes in the Philippines This is a list of inactive volcanoes in the Philippines. Volcanoes with no record of eruptions are considered as extinct or inactive. Their physical form since their last activity has been altered by agents of weathering and erosion with the for ...
*
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 ...


References


External links


Philippine Institute of Volcanology and Seismology (PHIVOLCS), Natib pageSmithsonian Institution's Global Volcanism Program, Natib page
{{Volcanoes of the Philippines Natib Natib Natib Natib Landforms of Bataan Natib Natib Pleistocene stratovolcanoes