Many years ago, in our previous home, I did a summary post on the Katmai region on the Alaskan Peninsula. There was another post in 2012 that discussed recent (at that time) earthquakes and speculated on possible future activity.
While I’ve known about Martin for many years, last November, the Smithsonian GVP raised it as possible topic, so I put it on the list of future volcanoes to discuss. As we’ve not discussed Alaska for a while, why not take a closer look at a pair of volcanoes at the SW end of the Katmai chain? The 1,863 m high Martin is located some 16 km SW from Novarupta, 453 km SW from Anchorage. In the following post, I’m going to use Novarupta as Ground Zero, the central measuring point.
Martin is a mostly ice-covered stratovolcano at the SW end of the Katmai volcano cluster in the Katmai National Park. It is built on the flank of the neighboring Alagogshak volcano immediately to the WSW. The volcanic structure is a small, fragmented cone constructed by at least 10 thick blocky dacite lava flows.
Neighboring Alagogshak volcano is only recently recognized as a stratovolcano. It is located along the volcanic front only a few kilometers SW of Martin. It has produced nearly 20 km3 of andesite – dacite material via intermittent eruptions over the last 600 k years.
On the other side of the volcanic front, the third neighboring volcano is Mageik, perhaps 8 km along the volcanic front to the ENE. In this post, I will be dealing with Martin and Alagogshak, and grouping neighboring Mageik with the Trident, Novarupta, Griggs, Katmai cluster discussed in 2014.
This portion of the volcanic front is heavily glaciated, which makes analysis of what is going on in the craters of the volcanoes problematic. Martin has vigorous fumaroles which have been mistakenly identified as small, phreatic eruptions, most recently in 2005. Recent activity has been earthquake swarms in 2012 and 2014.
The Katmai – Novarupta region is remote, with less than 1,000 living within 100 km of the region. The Alaska Volcano Observatory does monitor multiple volcanoes in the Katmai group with both webicorders and webcams. Martin’s webicorder can be found here. The Katmai webcam is not currently operating.
The Katmai volcanic group is surrounded by Katmai National Park & Preserve. It was established in 1918 following the devastation of the 1912 Katmai – Novarupta eruption and creation of the Valley of Ten Thousand Smokes. Today, it is frequented by visitors and guides. The region has over 9,000 years of human habitation.
It also has significant wildlife, particularly salmon and brown bears. Bear viewing present and remote is extremely popular, with Brooks Camp being the most popular destination. Occasionally, visitors choose poorly and become one with the bear as self-described Bear Whisperer Timothy Treadwell and his girlfriend did in 2003. The attack was fully captured on audio, some of which was not released to the public due to its graphic nature. Treadwell used to record his interactions with bears.
Weather in Katmai is generally wet and cool, spring summer to fall with temperatures ranging from freezing to as high as 27°. Winters are even more variable than summers, ranging from -37° – +10° C. Most ponds and lakes are frozen by mid to late fall. Snow covers higher elevations of the park until late May – early June. Strong winds and storms are more common along the coast than in the interior of the park. Visitors are advised to bring high quality waterproof clothing, layer up, and keep heads and hands covered.
Katmai Cluster
The heart of Katmai is a cluster of five stratovolcano groups. It also includes the 1912 Novarupta vent, a massive ignimbrite flow in the Valley of Ten Thousand Smokes, and the caldera lake occupying Mount Katmai. The magma plumbing system under the cluster is complex, as demonstrated in the 1912 eruption, where the source of the Plinian eruption and ignimbrite was separated from the newly formed Katmai caldera by 10.5 km. Stratovolcanoes in this cluster from S to N include Mageik, Trident, Griggs and Katmai. Novarupta is not a stratovolcano, though part of the group.
Mount Mageik is a broad stratovolcano on the volcanic front. It tops out at 2,165 m and shares the ridge line with Mount Martin and Alagogshak 6.5 km SW. Mageik is 9.5 km SW from Novarupta. It is ice-capped and sits at the head of the Valley of Ten Thousand Smokes across Katmai Pass from Trident. The volcano has four small overlapping peaks on the summit. The central summit has a dome. Other peaks are cones with ice-filled craters. The East Mageik summit cone was the source for at least six Holocene eruptions and fed lava flows on the NE – SE flanks of the volcano. There is a young explosion crater between east and central summits filled with a shallow lake. There are three debris avalanches from the S flank, one of which may have reached the coast. One of these took place during the 1912 eruption to the S and E of Mageik.
Trident is a cluster of four overlapping stratovolcanoes with at least 23 lava domes on its flanks. The summit complex is 3 – 5 km SE of Novarupta and merges into the ridge defining the volcanic front with Mount Katmai. The peaks are all glaciated. The youngest, SW Trident was formed during historic time. Eruptions migrated NE – SW over time. There were a series of thick andesitic lava flows erupted 1953 – 1968 forming a cone. Periodic explosions took place until 1974. Some lava flows on Trident’s western flanks collapsed into the Novarupta vent during the 1912 eruption. The cluster tops out at 1,864 m.
Novarupta is the vent that sourced the 1912 eruption, its Plinian plume and the ignimbrite filling the Valley of Ten Thousand Smokes. It is the least topographically prominent volcano in the Katmai cluster topping out at 841 m. The funnel-shaped structure is 2 km wide, plugged with a 400 m diameter 65 m high dome. There are prominent scarps on the flanks of surrounding mountains from subsidence into the depression. Novarupta is 4 km behind (WNW) the volcanic front defined by Mageik, Trident, Katmai. There are linear fractures normal to the volcanic front between Novarupta and Trident.
2047 m tall Mount Katmai was initially thought to be the source of the 1912 eruption, as it was the most obvious new collapse structure following the eruption. Further analysis moved the eruption source to the Novarupta vent 10.5 km W. Katmai is a compound stratovolcano with four summits, most of which were truncated by the caldera collapse in 1912. It was the source of at least two large explosive eruptions in the later Pleistocene. There are Holocene lava flows from a flank vent to the SE flank into Katmai River canyon. The new 3 x 4 km caldera is filled with a 250 m deep, rising lake. Lake waters covered a post-collapse dome. Three post-collapse glaciers are growing within the caldera. Much of the volcano is glaciated.
The final volcano in the group is Griggs, a full 10 km to the W of the volcanic front, 10 km NNE of Novarupta. It is a broad stratovolcano, formerly known as Knife Peak, truncated on its SW side by a flank collapse / debris avalanche. A Holocene volcano was constructed within the 1.5 km wide amphitheater. Three concentric craters mostly fill the scarp. Thick, blocky lava flows blanket the SW flank of the volcano below the collapse scarp. Flows from Griggs are generally andesitic unlike the dacites of the rest of the cluster. There have been no observed eruptions, but the system has active fumaroles. Griggs is 2,317 m high with a total volume around 25 km3. It does not appear that the Griggs plumbing system is connected to the rest of the Katmai cluster.
Alagogshak
Alagogshak is a rather recently recognized volcano front stratovolcano. It is located some 15 km SW of Katmai Pass, 95 km SE from King Salmon on the Alaska Peninsula. It produced 10 – 18 km3 of andesite – dacite eruptive products in several eruptive episodes over 600 ka. Rocks in the central vent are hydrothermally altered. Stacks of lava flows extend 6 – 10 km from the central vent in most directions. These products are varied, probably reflecting evolution of multiple magma batches over the 600 ka lifetime of the system. In contrast, neighboring Martin, on the Alagogshak flank 3 km NE has produced far more coherent eruptive products. The most recent lava production from Alagogshak was 43 ka, after which volcanic activity shifted 3 km NE to the Martin vent.
Perhaps as much as two-thirds of Alagogshak has been stripped by glacial erosion. The original coverage of its volcanic products may have been as much as 60 – 90 km2. The estimated volume of 10 – 18 km3 is much smaller than that of neighboring Mageik (30 km3) and Griggs (20 – 25 km3), but larger than the young Martin vent (5 km3). There is no evidence of voluminous tephras from Alagogshak, meaning eruptions were generally effusive.
The heavily eroded vent today is an amphitheater that holds a NW draining glacier. The walls of the vent are coarse scoria beds, poorly sorted phreatomagmatic ejecta layers with dense, glassy blocks. There is a 140 m thick black, glassy dacite lava flow present. Stacks of lava flows dip radially from the vent and are well preserved in several sectors. Some of these stacks are as much as 300 m thick with individual flows 10 – 30 m thick.
The various stacks have been dated, with ages generally 680 – 104 ka. The youngest dated 43 ka. The oldest outlier dated at 954 ka. While 600 – 900 ka is relatively long-lived for an andesite – dacite volcano, it is not extraordinarily long lived, and has a life span similar to a number of Cascade volcanoes that erupted intermittently for comparatively long times. This sort of behavior seems to require longer periods of repose separating periods of activity.
Alagogshak has not been recently active and may be extinct like its neighbor to the SW, Kejulik. If so, this leaves a 122 km activity gap between recently active Martin and Peulik. This gap is in stark contrast with the closely spaced volcanoes of the Katmai cluster, along a 25 km stretch of the volcanic front to the NE from Martin.
Mount Martin
Mount Martin is a small Holocene volcano overlapping the NE edge of the Alagogshak volcanic edifice. Its initial activity took place some 30 ka after Alagogshak’s last known activity. It is constructed of a small fragmental cone and a staircase of at least 10 overlapping coulees of blocky dacite lavas, 75 – 100 m thick. These stretch as far as 10 km NW. The summit tops out above 1,860 m, though only 500 above the ridge it was constructed upon. The cone is 2 km wide with a crater holding active fumaroles. The cone is less than 5% of all eruptive products, with the 31 km2 lava flow field making up the rest of the estimated 7 km3. Eruptive products have changed over time, with the lava flows being dacites and the cone and its ejected debris generally andesitic.
Mount Martin is just SW of the Katmai volcanic cluster in Katmai National Park. It was named for the first person to visit the region following the 1912 eruption. The volcano is relatively new, not older than the Holocene, constructed on the flank of adjacent Alagoshak volcano WSW along the volcanic front.
The size of Martin has been overestimated due to its proximity to neighboring Alagogshak volcano. Martin has a ring of active glaciers, but erosion of the cone and coulees is insignificant at best.
Typical activity from Martin is summit fumaroles, often putting steam plumes as high as a kilometer above the summit. The cone ejects a persistent steam plume with as many as 20 vigorous fumaroles. These precipitate sulfur in the cone material NW of the shallow acidic lake on the floor of the 300 m wide crater. Audible jetting from the active fumaroles can be heard from as far as 16 km away, indicating high velocity outgassing from Martin.
Significant quantities of SO2 are released from Mount Martin in comparison with neighboring volcanoes. This suggests a significant contribution of high-temperature magmatic gasses to the total gas emissions from the volcano. Gas from Martin’s summit fumaroles was sampled via aircraft five times 1998 – 2006. Sampling found traces of SO2, CO2 and H2S. Interestingly, only one of the trips found appreciable amounts of CO2. Two of the other trips found trace amounts. The other two found none.
There were two reports of historic eruptions attributed in a 1954 paper to Martin, though there have been no observed eruptions. AVO lists 14 reports of steam plumes above Martin 1913 – 2005. There were occasional episodes of increased seismicity in Oct 1996, Dec 1998, May – July 1999, Jan 2006 (the largest swarm since monitoring began), Jun 2007, Dec 2008 and Oct 2014. The Jan 2006 swarm was by far the largest.
The most significant seismic swarm at Martin took place over a week in Jan 2006. 300 earthquakes recorded in two days, a total of 860 locatable quakes over the course of the week. No quake was larger than M 2. Normal activity is around 25/mo since the seismic network was installed in 1996. AVO did increase the color code to Yellow due to this swarm. Satellite and pilot observations did not indicate anything out of the ordinary.
The triggering mechanism for the swarm was originally unknown. The short duration, similarity in observed focal mechanisms, and the lack of other signs of unrest suggest that a large magma injection beneath the volcano was not responsible for the swarm. However, a small volume magma or fluid injection into a dike 0 – 3 km below sea level beneath Martin’s summit may have been. By 2017, mainly due to subsequent gas sample analysis, the 2006 swarm is now thought to be an injection of a smallish magma batch into a shallow location beneath the volcano. Changes in sampled gas since then are therefore due to residual degassing of the 2006 magma injection.
Tectonics
Volcanic activity in the Katmai region like all volcanic activity along the Alaska Peninsula and Aleutians is driven by the subduction of the Pacific Plate beneath North America. This portion of the volcanic arc, the Eastern Aleutians, is segmented into the Cook and Katmai segments. Larger caldera forming volcanoes are located near segment boundaries. Intrasegment volcanoes are smaller stratocones. Ten of the 22 volcanoes along the 540 km long volcanic front have erupted in recorded history. Another six show hydrothermal activity.
The Benioff zone dips at 45° beneath the volcanic arc to a maximum depth of 200 km. The Cook and Katmai segments are not parallel, but are misaligned by 35°. This is thought to reflect a change in strike and perhaps a lateral warping of the subducting plate. Cook segment volcanoes to the N of Katmai line up at the 100 km isobath. Katmai segment volcanoes lie on a change in the underlying seismic zone from 75 – 100 km. There is good evidence that crustal tectonics play an important role in localizing volcanism, as narrowly spaced linear groups of volcanoes appear to be positioned on a deep crustal fault underlying the volcanic front. Transverse faults divide the arc into subsegments and localize larger magma reservoirs at shallow depths.
Intrasegment volcanoes tend to erupt andesites with minor dacites. These products are uniform. Segment boundary volcanoes erupt a wider range of magmas including basalts and rhyolites. Greater crust thickness in this region allow magma ponding at shallow levels, which in turn differentiates producing dacites and rhyolites.
Conclusions
As of this writing, Alagogshak appears to be mostly dormant, with activity shifting ENE along the volcanic front 3 km to the more recent Mount Martin. Martin gets periodic injections of new magma and has sufficient thermal potential to drive a vigorous system of fumaroles at its summit. These fumaroles appear to be driven by magmatic gasses from recently delivered packets of magma beneath the volcano. While relatively small and young as compared with other neighboring volcanoes, Martin appears to be driven by active delivery of new magma beneath it.
Additional information
AVO – Alagogshak description and information
AVO – Mount Martin description and information
Explosive eruptive record in the Katmai region, Alaska Peninsula: an overview, J Fierstein, 2007
agimarc
Spica
Granyia
volcanohotspot.wordpress.com 
Video courtesy Breitbart this morning of Sakurajima erupting over a soccer game on July 17. Video looked across the playing field in Kyushu while the plume rises. Ref started the game anyway. volcano is 22 km from the field. Visiting team won 1-0. Cheers –
https://california18.com/volcano-erupts-near-soccer-field-and-the-game-continues-as-if-nothing/5846492022/
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