The magma supply rate measures the production rate of

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

at a

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 ...

. Global magma production rates on Earth are about .

Definitions

Magma supply rate is also known as the Armstrong unit, where 1 Armstrong Unit = . Armstrong unit can also refer to volcanic

flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications in physics. For transport phe ...

rate per length of arc in discussions of

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...

s, in that case km2/year. Sometimes in discussion of large volcanic systems such as

s the volcanic flux rate is normalized to a surface area, similar to Darcy's law in

hydrodynamic In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in moti ...

s. It is often easier to measure magma supply rates when they are normalized for an exposed surface area as it is often difficult to delimit an

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

Measurement difficulties

Estimating the volcanic flux rate or magma supply of a volcanic system is inherently difficult for a number of reasons, and different measurements can come to different conclusions about the volcanic flux rate of a given volcanic system. Not all volcanic bodies are equally well exposed, and it is often impossible or difficult to measure magma supply rates exactly. Furthermore, volcanic flux rates often vary over time, with distinct lulls and pulses. Wall rocks may be assimilated by magma or magma may undergo differentiation such as crystallization. Magma contains vesicles and volcanic edifices are often

eroded Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is disti ...

. The sizes of volcanic edifices and plutons are difficult to estimate, especially in

s which are mostly buried.

Applications

The magma supply rate is used to infer the behaviour of volcanic systems which erupt periodically, as well as to describe the growth of the continental crust and of deep-seated magmatic bodies such as plutons. Magma output is usually larger in oceanic settings than in continental ones, and

basaltic 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% ...

volcanic systems produce more magma than silicic ones.

Table of selected flux rates

}--> , - , Mount Sidley , , , , , - , Nevado Tres Cruces , , 1.5-0.03 mya , Volume/Duration , , - ,

Parinacota Parinacota (in Hispanicized spelling), Parina Quta or Parinaquta ( Aymara, ''parina'' flamingo, ''quta'' lake, "flamingo lake", other Hispanicized spellings ''Parinaccota, Parinajota'') may refer to: Lakes * Parinaquta (Carabaya), in Peru, Puno ...

, , Since Late Pleistocene. , Volume/Duration , , - ,

, , Last 8,000 years. , Volume/Duration , , - ,

, Young Cone prior to 8.1 ka , , 1000–2000 years long. , , , - , Ruapehu , , 250,000 years , Total volume/Lifespan , , - , Ruapehu, Mangawhero formation , , , , , - , Ruapehu, Te Herenga formation , , , , , - , Ruapehu, Waihianoa formation , , , , , - , Ruapehu, Whakapapa formation , , , , , - ,

Samoa Samoa, officially the Independent State of Samoa and known until 1997 as Western Samoa, is an island country in Polynesia, part of Oceania, in the South Pacific Ocean. It consists of two main islands (Savai'i and Upolu), two smaller, inhabited ...

, , 3 million years , Total volume of edifices/age, neglecting

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

and eroded material , , - , San Francisco Mountain , , ≤ 400 ka , Total volume/Duration, including landslide removals , , - , San Francisco Mountain, main shield building stage , , ~ 100 ka , Total volume/Duration, including landslide removals , , - , San Pedro de Tatara , , , Total volume/Duration, including glacially eroded volumes , , - , Santa Maria , , 103-35 ka , , , - , Santa Maria , , 103 ka – 1902 , , , - ,

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

, , A single pluton plumbing system , Volume of plutons/emplacement time , , - ,

Society Islands The Society Islands ( , officially ; ) are an archipelago in the South Pacific Ocean that includes the major islands of Tahiti, Mo'orea, Moorea, Raiatea, Bora Bora and Huahine. Politically, they are part of French Polynesia, an overseas country ...

, , 5 million years , Total volume of edifices/age, neglecting

and eroded material , , - , Soufrière Hills , , Last 174 ka , Total volume/Duration , , - , Stromboli , , , Magma intrusion needed to create the measured

sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

emissions. , , - , Tancítaro , ≤ , ≥ 550 ka , Total volume/Duration , , - ,

Tenerife Tenerife ( ; ; formerly spelled ''Teneriffe'') is the largest and most populous island of the Canary Islands, an Autonomous communities of Spain, autonomous community of Spain. With a land area of and a population of 965,575 inhabitants as of A ...

, , Long term average , Total volume/Duration , , - ,

, Old Basaltic Series , , 8-4 million years ago , Estimated volume/Duration , , - ,

, Cañadas I volcano , , 1 million years , Estimated volume/Duration , , - ,

, Cañadas II volcano , , 0.8 million years , Estimated volume/Duration , , - ,

, Cordillera Dorsal , , 0.2 million years , Estimated volume/Duration , , - ,

, Teide- Pico Viejo , , 0.2 million years , Estimated volume/Duration , , - , Tunupa- Huayrana , , 240,000–90,000 years , , , - , Ubinas , , < 376 ka , Cone volume/Duration , , - ,

Yellowstone Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

, , Long term average , ,

References

{{Volcanoes Volcanology