Hayes Volcano
Encyclopedia
Hayes Volcano is a stratovolcano
in southwestern Matanuska-Susitna Borough, Alaska
, 135 km northwest of Anchorage
, that was not discovered until 1975. It is responsible for a series of six major tephra
layers in the Cook Inlet region of Alaska. Hayes was mostly destroyed by at least six catastrophic eruptions between 3,400 and 3,800 years ago, and the average volume of these eruptions was 2.4 cubic km. In comparison, the volume of the May 18, 1980 eruption of Mount St. Helens
was about 1 cubic km. The eruptions of Hayes Volcano during that time were the most voluminous Holocene
eruptions to have occurred in the Cook Inlet region. There is currently no fumarolic
activity present. The last eruption of Hayes Volcano occurred roughly 1,200 years ago. It is named after the adjacent Hayes Glacier
.
age composed
of pyroclastic deposits, volcanic breccia
, and lava dome
s. Although the edifice of the volcano is
largely covered by glacier ice, parts of small lava domes, dome debris, and pyroclastic deposits project
through the ice at altitudes of 2,400 to 2,800 meters above sea level. The volcano is nestled within the Tordrillo Mountains, a rugged, glacier-clad mountain range, between the Alaska Range
and Cook Inlet, that
is composed primarily of older plutonic
igneous rock
s. Most of the area is in high relief (greater than 1,500 meters) and supports an extensive complex of glacier ice that covers most of the mountainous terrain. The volume of perennial snow and glacier ice on Hayes Volcano is not known but is comparable to the ice volume present on Mount Spurr
volcano (to the south), which supports about 67 km³ of ice and perennial snow.
Unlike the other volcanoes in the Cook Inlet area, Hayes Volcano lacks a well-defined cone, and deposits from eruptions older than the 4,400-to-3,600-year-old eruption are not known. The volcano is unusual in this regard because all other volcanoes in the Cook Inlet area consist of relatively voluminous assemblages of volcanic rock and debris that formed over many tens of thousands of years.
apparent on the volcano. During trips to the volcano in 1999 and 2000, signs of volcanic unrest, such as melting of glacier ice, steaming, or discoloration of the ice surface by volcanic ash were not observed.
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
in southwestern Matanuska-Susitna Borough, Alaska
Matanuska-Susitna Borough, Alaska
-National protected areas:* Chugach National Forest * Denali National Park and Preserve ** Denali Wilderness * Lake Clark National Park and Preserve ** Lake Clark Wilderness -Demographics:...
, 135 km northwest of Anchorage
Anchorage, Alaska
Anchorage is a unified home rule municipality in the southcentral part of the U.S. state of Alaska. It is the northernmost major city in the United States...
, that was not discovered until 1975. It is responsible for a series of six major tephra
Tephra
200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
layers in the Cook Inlet region of Alaska. Hayes was mostly destroyed by at least six catastrophic eruptions between 3,400 and 3,800 years ago, and the average volume of these eruptions was 2.4 cubic km. In comparison, the volume of the May 18, 1980 eruption of Mount St. Helens
Mount St. Helens
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...
was about 1 cubic km. The eruptions of Hayes Volcano during that time were the most voluminous Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
eruptions to have occurred in the Cook Inlet region. There is currently no fumarolic
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
activity present. The last eruption of Hayes Volcano occurred roughly 1,200 years ago. It is named after the adjacent Hayes Glacier
Hayes Glacier
Hayes Glacier enters the south east part of Weddell Sea about 27 km west south west of Dawson-Lambton Glacier. The glacier was discovered in the course of a U.S. Navy LC-130 plane flight over Caird Coast, November 5, 1967, and was plotted by United States Geological Survey from photographs...
.
Physical setting
Hayes Volcano is an ice-shrouded, glacially scoured eruptive center of QuaternaryQuaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
age composed
of pyroclastic deposits, volcanic breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
, and lava dome
Lava dome
|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...
s. Although the edifice of the volcano is
largely covered by glacier ice, parts of small lava domes, dome debris, and pyroclastic deposits project
through the ice at altitudes of 2,400 to 2,800 meters above sea level. The volcano is nestled within the Tordrillo Mountains, a rugged, glacier-clad mountain range, between the Alaska Range
Alaska Range
The Alaska Range is a relatively narrow, 650-km-long mountain range in the southcentral region of the U.S. state of Alaska, from Lake Clark at its southwest end to the White River in Canada's Yukon Territory in the southeast...
and Cook Inlet, that
is composed primarily of older plutonic
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
igneous rock
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
s. Most of the area is in high relief (greater than 1,500 meters) and supports an extensive complex of glacier ice that covers most of the mountainous terrain. The volume of perennial snow and glacier ice on Hayes Volcano is not known but is comparable to the ice volume present on Mount Spurr
Mount Spurr
Mount Spurr is a stratovolcano in the Aleutian Volcanic Arc of Alaska, named after United States Geological Survey geologist and explorer Josiah Edward Spurr, who led an expedition to the area in 1898...
volcano (to the south), which supports about 67 km³ of ice and perennial snow.
Unlike the other volcanoes in the Cook Inlet area, Hayes Volcano lacks a well-defined cone, and deposits from eruptions older than the 4,400-to-3,600-year-old eruption are not known. The volcano is unusual in this regard because all other volcanoes in the Cook Inlet area consist of relatively voluminous assemblages of volcanic rock and debris that formed over many tens of thousands of years.
Historical eruptions
Historical eruptions of Hayes Volcano are not known and evidence of recent eruptive activity is notapparent on the volcano. During trips to the volcano in 1999 and 2000, signs of volcanic unrest, such as melting of glacier ice, steaming, or discoloration of the ice surface by volcanic ash were not observed.