Gigantic debris avalanche of Pleistocene age from ancestral Mount Shasta Volcano, California, and debris-avalanche hazard zonation

Crandell, Dwight Raymond

doi:10.3133/b1861

Cited by 17 publications

(3 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Toreva blocks are commonly composed of one or more blocks that slide and retain the original stratigraphic sequence, whereas hummocks are mound features composed of block material in the surface with a form of conical shape and have a height of tens to hundreds of meters (Ui, 1983;Stoopes and Sheridan, 1992). Hummock sizes in the Naga deposit field decrease in dimension away from the headscarp, consistent with the descriptions in other debris avalanche deposits (Reiche, 1937;Ui, 1983;Crandell et al, 1989;Thompson et al, 2010;de Vries and Delcamp, 2015). The high-resolution DEM also reveals that the highest elevation of the failure is at 255 masl, whereas the elevation at the toe in Lobes 1 and 2 is 50 and 70 masl, respectively.…”

Section: Morphologysupporting

confidence: 62%

Anatomy of the Naga City Landslide and Comparison With Historical Debris Avalanches and Analog Models

et al. 2020

View full text Add to dashboard Cite

Debris avalanches pose some of the most destructive geologic hazards that threaten both urban and rural populations around the world. On 20 September 2018, villages in Naga City, Cebu, Philippines, were devastated by a landslide that claimed 78 lives with 6 missing, joining other catastrophic landslides in the country like the 1628 Iriga and the 2006 Guinsaugon debris avalanches. Understanding the mechanism of these gargantuan landslides and their correct nomenclature are useful for hazard prevention and mitigation. In this study, we compare the deposit characteristics of the Naga City landslide with analog models and well-known historical debris avalanche events/deposits in the Philippines to understand factors that led to the landslide disaster in Naga City. Physical characteristics obtained from aerial and satellite imagery, ground surveys, recorded footage, borehole data, and lithologic maps provided a detailed dataset for analyzing the conditions that led to the mass movement and the observed characteristics of the Naga landslide deposits. Comparison with analog models of hummock formation and the description of historical debris avalanche deposits show striking similarities, which were used to demonstrate that the Naga landslide was a Rockslide-Debris Avalanche. The equations of Corominas (1996) and Dade and Huppert (1998) for long-runout rockfalls support this analysis. The Naga landslide event is an example of a well-documented debris avalanche, complete with all the characteristics of this type of rapid mass movement. It is consistent with the descriptions found in the literature with respect to its deposit features and mechanical behavior as defined by laboratory models and empirically-derived equations. This study helps us understand historical and future long-runout debris avalanches in order for scientists and authorities to find ways to save lives. Unfortunately, there was lack of appropriate hazards assessment on the site, which had warnings in the form of the development of fractures at the headscarp of the landslide, a month prior to the disaster.

show abstract

Section: Morphologysupporting

confidence: 62%

Anatomy of the Naga City Landslide and Comparison With Historical Debris Avalanches and Analog Models

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Hydrothermal alteration on other stratovolcanoes in the Quaternary Cascades arc generally is not well studied, and high-temperature hydrothermal-alteration assemblages have not been described on volcanoes that have been studied in more detail (e.g., Mounts Hood and Shasta, Bargar et al, 1993;Crowley et al, 2003;Zimbelman et al, 2005). Especially noteworthy is the near absence of hydrothermally altered rock in the ~45 km 3 debris-avalanche deposit formed by collapse of ancestral Mount Shasta (Crandell, 1989). The eroded Pliocene Yana and Dittmar stratovolcanoes near Lassen Peak (Fig.…”

Section: ■ Comparison To Hydrothermal Activity On Other Arc-related Smentioning

confidence: 99%

Pleistocene hydrothermal activity on Brokeoff volcano and in the Maidu volcanic center, Lassen Peak area, northeast California: Evolution of magmatic-hydrothermal systems on stratovolcanoes

et al. 2019

View full text Add to dashboard Cite

Partially eroded stratovolcanoes worldwide, notably Mounts Rainier and Adams in the Cascades and several volcanoes in Japan, record episodic periods of eruption and geothermal activity that produce zones of hydrothermal alteration. The partly eroded core of late Pleistocene Brokeoff volcano on the south side of Lassen Peak exposes the upper 1 km of multiple ancient (ca. 410-300 ka) magmatic-hydrothermal alteration zones in a 3.5 by 5 km area that allows characterization of the three-dimensional hydrothermal evolution of the volcano. Both acid-and neutral-pH hydrothermal solutions produced distinctive alteration mineral assemblages in close proximity. Early hydrothermal activity is characterized by alunite-rich alteration that is temporally and spatially related to shallow intrusions in the center of the volcano. Younger acid alteration and a large area of neutral-pH alteration formed along the volcano's flanks. The neutral-pH alteration is vertically zoned over 1000 m from shallow zeolite ± adularia through intermediate argillic (smectite-pyrite ± illite) to deep propylitic (chlorite-calcite-albite-illite) alteration. Pleistocene alteration is partly overprinted by surficial, steam-heated alteration related to Lassen's modern hydrothermal activity. A large (~3.5 km 2), shallow (≤300 m), ca. 1.5 Ma alunite-rich magmatic-hydrothermal alteration zone is exposed on the northeast flank of the nearby Maidu volcanic center. Hydrothermal activity occurred just prior to, or at the beginning of, major eruptive periods on both volcanoes. Fluid flow and hydrothermal alteration were controlled by primary permeability (lateral fluid flow driven by paleotopographic groundwater gradients in volcaniclastic rocks), steeply dipping fractures in more deeply exposed parts of alunite-rich alteration zones, and inferred basement structures. Stable-isotope data indicate hydrothermal fluids were mixtures of variably exchanged meteoric and magmatic waters. Variations in types of hydrothermal alteration and fluid compositions may reflect a temporal increase in depth of magma emplacement and degassing that resulted in increased interaction with and neutralization by wall rocks during ascent of magmatic gases. Alteration zones on both volcanoes are not strongly mineralized, probably reflecting relatively low amounts of magmatic acid, sulfur, and chlorine consistent with degassing of small volumes of pyroxene andesite magma compared to large dacite and/or granodiorite batholiths that form significant epithermal and porphyry deposits.

show abstract

“…430 and 320 ka, and little is known of its original constitution, vent(s), or form. The debris-avalanche deposit produced during the sector collapse has a volume of ~45 km 3 (Crandell et al, 1984;Crandell, 1989). Nevertheless, the remaining, largely buried edifice probably has a total volume of ~180 km 3 (Blakely et al, 2000), including part of the volcano that lies isostatically depressed beneath the level of the surrounding surface, perhaps as well as part of its intrusive core.…”

Section: ■ Brief Summary Of Mount Shasta's Volcanic Evolutionmentioning

confidence: 99%

The remarkable volcanism of Shastina, a stratocone segment of Mount Shasta, California

et al. 2020

View full text Add to dashboard Cite

Mount Shasta, a 400 km3 volcano in northern California (United States), is the most voluminous stratocone of the Cascade arc. Most Mount Shasta lavas vented at or near the present summit; relatively smaller volumes erupted from scattered vents on the volcano’s flanks. An apron of pyroclastic and debris flows surrounds it. Shastina, a large and distinct cone on the west side of Mount Shasta, represents a brief but exceptionally vigorous period of eruptive activity. Its volume of ~13.5 km3 would make Shastina itself one of the larger Holocene Cascade stratovolcanoes. Its andesite-dacite lavas average 63 wt% SiO2 and have little compositional or petrographic variation; they erupted almost entirely from one central vent, although a single vent below Shastina’s north side erupted a flow of the same composition. Eruptions ended with explosive enlargement and breaching of the central crater and successive emplacement of four, more-silicic dacite domes within the crater and pyroclastic flows down its flank. Black Butte, a large volcanic dome and pyroclastic complex below the west flank of Shastina, is petrographically and chemically distinct but only slightly younger than Shastina itself, part of a nearly continuous Shastina–Black Butte eruptive episode. Shastina overlies the widespread pumice of Red Banks, erupted from the Mount Shasta summit area and 14C dated at ca. 10,900 yr B.P. (calibrated). Shastina and Black Butte pyroclastic deposits have calibrated 14C ages indistinguishable from one another at ca. 10,700 cal. yr B.P. A cognate granitic-textured inclusion in a late Shastina lava flow yields a 238U-230Th date on zircons within error of those ages. Our conclusion that the entire, voluminous Shastina–Black Butte episode lasted no more than a few hundred years is confirmed by almost identical remanent magnetic directions of all of the lavas and pyroclastic deposits. Although extremely similar, the remanent magnetic directions do reveal a short path of secular variation through the eruptive sequence. We conclude that the entire Shastina–Black Butte eruptive episode lasted no more than ~200 yr. The magmas that produced the Shastina and Black Butte eruptions were separate individual bodies at different crustal levels. Each of these eruptive sequences probably represents magma approximating a liquid composition that experienced only minimal differentiation or crustal contamination and remained separated from the main central conduit for most eruptions of Mount Shasta. The probability of another rapidly developing, brief but voluminous eruptive episode at Mount Shasta is low but should not be ignored in evaluating future possible eruptive hazards.

show abstract

Gigantic debris avalanche of Pleistocene age from ancestral Mount Shasta Volcano, California, and debris-avalanche hazard zonation

Cited by 17 publications

References 23 publications

Anatomy of the Naga City Landslide and Comparison With Historical Debris Avalanches and Analog Models

Anatomy of the Naga City Landslide and Comparison With Historical Debris Avalanches and Analog Models

Pleistocene hydrothermal activity on Brokeoff volcano and in the Maidu volcanic center, Lassen Peak area, northeast California: Evolution of magmatic-hydrothermal systems on stratovolcanoes

The remarkable volcanism of Shastina, a stratocone segment of Mount Shasta, California

Contact Info

Product

Resources

About