Reconstructing the volume and tephra dispersal from
volcanic super-eruptions is necessary to assess the widespread
impact of these massive events on climate, ecosystems and humans.
Recent studies have demonstrated that volcanic ash transport and
dispersion models are unrivaled in accurately constraining the
volume of material ejected and provide further insight about the
eruption dynamics during these gigantic events. However, the
conventional simplified characterization of caldera-forming supereruptions
as a single-phase event can lead to inaccurate estimations
of the eruption dynamics and its impacts. Here, we apply a novel
computational inversion method to reconstruct, for the first time, the
two phases of the largest eruption of the last 200 ky in Europe, the
Campanian Ignimbrite (CI) super-eruption. Additionally, we discuss
the eruption’s contribution to the Middle to Upper Paleolithic
transition by evaluating its environmental and climate implications

Costa, Antonio

Engwell, Samantha

Folch, Arnau

Marti, Alejandro

Reconstructing the volume and tephra dispersal from

volcanic super-eruptions is necessary to assess the widespread

impact of these massive events on climate, ecosystems and humans.

Recent studies have demonstrated that volcanic ash transport and

dispersion models are unrivaled in accurately constraining the

volume of material ejected and provide further insight about the

eruption dynamics during these gigantic events. However, the

conventional simplified characterization of caldera-forming supereruptions

as a single-phase event can lead to inaccurate estimations

of the eruption dynamics and its impacts. Here, we apply a novel

computational inversion method to reconstruct, for the first time, the

two phases of the largest eruption of the last 200 ky in Europe, the

Campanian Ignimbrite (CI) super-eruption. Additionally, we discuss

the eruption’s contribution to the Middle to Upper Paleolithic

transition by evaluating its environmental and climate implications

UPCommons

  
 
 
~ 81 ~ 
A novel approach to reconstruct the plinian and co-ignimbrite phases of 
large eruptions  - Campanian Ignimbrite 
 
Alejandro Marti (*)(1), Arnau Folch (1), Antonio Costa (2), and Samantha Engwell (3) 
(1) CASE Department, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain 
(2) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy  
(3) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Italy 
(*) Alejandro.Marti@bsc.es 
Abstract- Reconstructing the volume and tephra dispersal from 
volcanic super-eruptions is necessary to assess the widespread 
impact of these massive events on climate, ecosystems and humans. 
Recent studies have demonstrated that volcanic ash transport and 
dispersion models are unrivaled in accurately constraining the 
volume of material ejected and provide further insight about the 
eruption dynamics during these gigantic events. However, the 
conventional simplified characterization of caldera-forming super-
eruptions as a single-phase event can lead to inaccurate estimations 
of the eruption dynamics and its impacts. Here, we apply a novel 
computational inversion method to reconstruct, for the first time, the 
two phases of the largest eruption of the last 200 ky in Europe, the 
Campanian Ignimbrite (CI) super-eruption. Additionally, we discuss 
the eruption’s contribution to the Middle to Upper Paleolithic 
transition by evaluating its environmental and climate implications. 
 
I. INTRODUCTION 
Volcanic super-eruptions, typically associated with caldera-
forming events, are often multiphase. The typical scenario 
begins with a Plinian column (Fig. 1a) which destabilizes to 
produce collapsing fountains that shed pyroclastic flows, 
spreading laterally along the ground1, eventually leading to 
secondary, co-ignimbritic plumes (Fig. 1b). Source conditions 
for co-ignimbrite plumes vary considerably from those of 
Plinian plumes, with much larger source radii and lower initial 
velocities. In eruptions where both phases have occurred, 
tephra deposits are typically bimodal. Such deposits are 
commonly separated into constituent phases based on their 
grainsize characteristics, with the coarse mode attributed to the 
Plinian phase, and the fine mode attributed to the co-
ignimbrite phase2. In order to correctly evaluate the magnitude 
of each eruptive phase, it is critical to constrain their eruption 
dynamics and quantify their Eruption Source Parameters 
(ESPs) independently.  
Here, we apply a novel computational approach to 
reconstruct, for the first time, the two phases of the largest 
eruption of the last 200 ky in Europe, the Campanian 
Ignimbrite (CI) super-eruption3 . It has been debated if the CI 
eruption, dated approximately 39.000 calendar years ago, was 
related to the disappearance of the remaining Neanderthals in 
Europe and, its interference with the territorial expansion of 
anatomically modern humans in the more southern parts of 
western Eurasia4. The event coincided with the onset of an 
extremely cold climatic phase (Heinrich Event 4) and the 
attendant episode of the Freno-Scandinavian ice cap and 
peripheral tundra on land. To conclude this work, we evaluate 
the environmental and climate-forcing implications associated 
to the eruption to provide new insights of the eruption’s 
contribution to the Middle to Upper Paleolithic transition.  
 
The aims of this conference paper are: 
(1) To quantify the volume and tephra dispersal across Europe 
and Mediterranean area during each phase of the event. 
(2) To describe the density-current effects in the umbrella cloud 
(3) To discuss the eruption’s contribution to the Middle to Upper 
Palaeolithic transition 
(4) To provide an outreach interactive website for more 
information on this work  
(http://www.bsc.es/viz/campanian_ignimbrite) 
 
II. METHODOLOGY 
To reconstruct the tephra dispersal and the ESPs of the CI 
eruption, we used the FALL3D tephra dispersal model5 in 
conjunction with a downhill simplex inversion method (DSM) 
to infer values of ESPs such as erupted mass, mass flow rate, 
plume height and total grain-size-distribution (TGSD). We 
compare the tephra dispersal and volume results from 
reconstructing the CI eruption as a two-phase event (Method 
1), with those form the classical single-phase approach6 
(Method 2). Optimal inversion values for the ESPs were 
obtained by best-fitting two independent datasets containing 
tephra deposits separated into constituent phases. To account 
for the gravitational cloud spreading associated to the CI 
eruption, we couple FALL3D with a model that accounts for 
the density-driven transport in the umbrella cloud7. 
 
III. RESULTS 
A. Method 1: two-phase approach 
Results for the best-fit model parameters for Method 1 
suggest that the eruption began with a short, high-intensity 
ultra-Plinian explosive phase that yielded a column height of 
Figure 1. . Illustration of a typical multi-phase super-eruption with an initial 
(a) Sustained Plinian phase; followed by a (b) Caldera-collapse and large 
pyroclastic density currents eventually leading to secondary, co-ignimbritic 
plumes offset from the vent. Nodes with grey outline represent the model 
domain used for the CI model simulations. Our simulations used a grid 
spacing 0.2 degrees latitude and longitude (~4km), and 1 km cell height. 
Red nodes illustrate the effect of the density-current and the corresponding 
transport regimes in the umbrella cloud based on the best-fit model 
parameters (blue text) associated to the CI event. 
  
 
 
~ 82 ~ 
44 km and a mass eruption rate (MER) of 3.75×109 kg/s. The 
Plinian phase lasted for 4 h, depositing a total of 54 km3 (~22 
km3 DRE) of fallout material. After that time, the column 
would have collapsed to form radially spreading pyroclastic 
density currents, thereby superseding the Plinian column phase 
and leading to a co-ignimbrite phase. The co-ignimbrite 
column would have reached 37 km in height, fed by an 
average MER of 2.25×109 kg/s over 19 h, depositing ~154 
km3 (~62 km3 DRE) of fallout material. Assuming that ~35-
40% of the erupted material was elutriated from PDC8 the total 
MER would have reached up to ~5-6×109 kg/s. 
 
B. Method 2: single-phase approach 
Best-fit simulation results from Method 2suggest a column 
height of 38 km, a mean MER of 2.55×109 kg/s and a duration 
of 23 hours. The amount of material deposited as tephra 
fallout totaled ~211 km3 (~84 km3 DRE).  
 
C. Method 1 vs. Method 2 
Method 1 is more accurate than the classical single-phase 
approach used in Method 2 (correlation coefficients 0.96 vs. 
0.74) and in previous studies6. Both methods confirm the 
dominant role of the co-ignimbrite phase in the total bulk 
volume of the eruption. The amount of material deposited as 
fallout amongst experiments differed in less than 1.5%, a very 
consistent result. Method 1 simulated the dispersal of tephra 
(0.5 cm thick or larger) to be 15% smaller than Method 2, and 
20% smaller than previous studies6. 
Figure 2. Model isopach maps showing the best-fit FALL3D tephra dispersal 
deposit (cm) for each phase of the CI super-eruption.  Tephra dispersal is 
shown for (a) the 44km high ultra-plinian plume accumulating a total of 54 
km3 of fallout material; (b) the 38 km co-ignimbrite plume accounting for 
74% of the total fallout material; (c) the combined Plinian and co-ignimbrite 
phases accumulating a total of 208 km3 of fallout material over ~3 million 
km2; (d) the classical single-phase approach for an eruption duration of 23h.  
D. Density-current effects 
We find the density-driven transport to be dominant for the 
first hour with an effective spreading radial velocity of ~130 
m/s and producing an umbrella cloud radius of ~100 km. 
Model results show the effect of the density-driven transport 
to be significant in proximal areas, where tephra deposition is 
1.5-2 times higher NE from the source and up to 50% lower in 
the east Mediterranean region due to the wind direction. These 
values are lower than expected for an eruption of such a 
magnitude. This is due to the strong stratospheric wind 
velocity of ~90 m/s found at the transport height above the 
vent. 
IV. CONCLUSIONS 
We bring to light valuable new results and methods in 
reconstructing the 39 ky CI super-eruption, accounting for 
both Plinian and co-ignimbrite phases. Simulation results 
show tephra fallout predominantly originated from the co-
ignimbrite clouds. Density-current processes would have been 
significant in proximal areas. However, tephra transport would 
have been primarily dominated by wind advection, most likely 
as a result of intense stratospheric winds corresponding to 
best-fit synoptic conditions. Ecosystem recovery would have 
required tens to thousands of years depending on the 
thickness, nature and distance from source of the tephra 
deposits.  
We suggest that the eruption would have cause a 
demographic crash among modern human populations boosted 
by the impact of the synchronous Heinrich Event 4 and the 
attendant episode of glacial advance on land. Such crash 
would have favoured the persistence of the Neanderthals in the 
Iberian Peninsula and not their disappearance as previously 
thought.  
ACKNOWLEDGMENT 
A.M. thanks the CASE visualization team at the BSC for 
their contribution to this work.   
 
REFERENCES 
1. Sparks, R. S. J., Wilson, L. & Hulme, G. Theoretical modeling of the 
generation, movement, and emplacement of pyroclastic flows by column 
collapse. J. Geophys. Res. Solid Earth 83, 1727–1739 (1978). 
 
2. Engwell, S. L., Sparks, R. S. J. & Carey, S. Physical characteristics of 
tephra layers in the deep sea realm: the Campanian Ignimbrite eruption. Geol. 
Soc. London, Spec. Publ. 398, 47–64 (2014). 
 
3. Fedele, F., Giaccio, B., Isala, R. & Orsi, G. The Campanian ignimbrite 
eruption, Heinrich event 4, and Palaeolithic change in Europe: a high-
resolution investigation. In Volcanism and the Earth’s Atmosphere 139, 301–
325 (American Geophysical Union, 2003). 
 
4. Zilhão, J. Neandertals and moderns mixed, and it matters. Evol. Anthropol. 
15, 183–195 (2006). 
 
5. Costa, A., Macedonio, G. & Folch, A. A three-dimensional Eulerian model 
for transport and deposition of volcanic ashes. Earth Planet. Sci. Lett. 241, 
634–647 (2006). 
 
6. Costa, A. et al. Quantifying volcanic ash dispersal and impact of the 
Campanian Ignimbrite super-eruption. Geophys. Res. Lett. 39, L10310 
(2012). 
 
7. Costa, A., Folch, A. & Macedonio, G. Density-driven transport in the 
umbrella region of volcanic clouds : Implications for tephra dispersion 
models. Geophys. Res. Lett. 40, 4823–4827 (2013). 
 
8. Sparks, R. S. J. & Walker, G. P. L. The significance of vitric-enriched air-
fall ashes associated with crystal-enriched ignimbrites. J. Volcanol. Geotherm. 
Res. 2, 329–341 (1977).


English

A Novel approach to reconstruct the plinian and co-ignimbrite phases of large eruptions - Campanian Ignimbrite

UPCommons. Portal del coneixement obert de la UPC

    ~ 81 ~ A novel approach to reconstruct the plinian and co-ignimbrite phases of large eruptions  - Campanian Ignimbrite  Alejandro Marti (*)(1), Arnau Folch (1), Antonio Costa (2), and Samantha Engwell (3) (1) CASE Department, Barcelona Supercomputing Center (BSC-CNS), Barcelona, Spain (2) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy  (3) Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Italy (*) Alejandro.Marti@bsc.es Abstract- Reconstructing the volume and tephra dispersal from volcanic super-eruptions is necessary to assess the widespread impact of these massive events on climate, ecosystems and humans. Recent studies have demonstrated that volcanic ash transport and dispersion models are unrivaled in accurately constraining the volume of material ejected and provide further insight about the eruption dynamics during these gigantic events. However, the conventional simplified characterization of caldera-forming super-eruptions as a single-phase event can lead to inaccurate estimations of the eruption dynamics and its impacts. Here, we apply a novel computational inversion method to reconstruct, for the first time, the two phases of the largest eruption of the last 200 ky in Europe, the Campanian Ignimbrite (CI) super-eruption. Additionally, we discuss the eruption’s contribution to the Middle to Upper Paleolithic transition by evaluating its environmental and climate implications.  I. INTRODUCTION Volcanic super-eruptions, typically associated with caldera-forming events, are often multiphase. The typical scenario begins with a Plinian column (Fig. 1a) which destabilizes to produce collapsing fountains that shed pyroclastic flows, spreading laterally along the ground1, eventually leading to secondary, co-ignimbritic plumes (Fig. 1b). Source conditions for co-ignimbrite plumes vary considerably from those of Plinian plumes, with much larger source radii and lower initial velocities. In eruptions where both phases have occurred, tephra deposits are typically bimodal. Such deposits are commonly separated into constituent phases based on their grainsize characteristics, with the coarse mode attributed to the Plinian phase, and the fine mode attributed to the co-ignimbrite phase2. In order to correctly evaluate the magnitude of each eruptive phase, it is critical to constrain their eruption dynamics and quantify their Eruption Source Parameters (ESPs) independently.  Here, we apply a novel computational approach to reconstruct, for the first time, the two phases of the largest eruption of the last 200 ky in Europe, the Campanian Ignimbrite (CI) super-eruption3 . It has been debated if the CI eruption, dated approximately 39.000 calendar years ago, was related to the disappearance of the remaining Neanderthals in Europe and, its interference with the territorial expansion of anatomically modern humans in the more southern parts of western Eurasia4. The event coincided with the onset of an extremely cold climatic phase (Heinrich Event 4) and the attendant episode of the Freno-Scandinavian ice cap and peripheral tundra on land. To conclude this work, we evaluate the environmental and climate-forcing implications associated to the eruption to provide new insights of the eruption’s contribution to the Middle to Upper Paleolithic transition.   The aims of this conference paper are: (1) To quantify the volume and tephra dispersal across Europe and Mediterranean area during each phase of the event. (2) To describe the density-current effects in the umbrella cloud (3) To discuss the eruption’s contribution to the Middle to Upper Palaeolithic transition (4) To provide an outreach interactive website for more information on this work  (http://www.bsc.es/viz/campanian_ignimbrite)  II. METHODOLOGY To reconstruct the tephra dispersal and the ESPs of the CI eruption, we used the FALL3D tephra dispersal model5 in conjunction with a downhill simplex inversion method (DSM) to infer values of ESPs such as erupted mass, mass flow rate, plume height and total grain-size-distribution (TGSD). We compare the tephra dispersal and volume results from reconstructing the CI eruption as a two-phase event (Method 1), with those form the classical single-phase approach6 (Method 2). Optimal inversion values for the ESPs were obtained by best-fitting two independent datasets containing tephra deposits separated into constituent phases. To account for the gravitational cloud spreading associated to the CI eruption, we couple FALL3D with a model that accounts for the density-driven transport in the umbrella cloud7.  III. RESULTS A. Method 1: two-phase approach Results for the best-fit model parameters for Method 1 suggest that the eruption began with a short, high-intensity ultra-Plinian explosive phase that yielded a column height of Figure 1. . Illustration of a typical multi-phase super-eruption with an initial (a) Sustained Plinian phase; followed by a (b) Caldera-collapse and large pyroclastic density currents eventually leading to secondary, co-ignimbritic plumes offset from the vent. Nodes with grey outline represent the model domain used for the CI model simulations. Our simulations used a grid spacing 0.2 degrees latitude and longitude (~4km), and 1 km cell height. Red nodes illustrate the effect of the density-current and the corresponding transport regimes in the umbrella cloud based on the best-fit model parameters (blue text) associated to the CI event.     ~ 82 ~ 44 km and a mass eruption rate (MER) of 3.75×109 kg/s. The Plinian phase lasted for 4 h, depositing a total of 54 km3 (~22 km3 DRE) of fallout material. After that time, the column would have collapsed to form radially spreading pyroclastic density currents, thereby superseding the Plinian column phase and leading to a co-ignimbrite phase. The co-ignimbrite column would have reached 37 km in height, fed by an average MER of 2.25×109 kg/s over 19 h, depositing ~154 km3 (~62 km3 DRE) of fallout material. Assuming that ~35-40% of the erupted material was elutriated from PDC8 the total MER would have reached up to ~5-6×109 kg/s.  B. Method 2: single-phase approach Best-fit simulation results from Method 2suggest a column height of 38 km, a mean MER of 2.55×109 kg/s and a duration of 23 hours. The amount of material deposited as tephra fallout totaled ~211 km3 (~84 km3 DRE).   C. Method 1 vs. Method 2 Method 1 is more accurate than the classical single-phase approach used in Method 2 (correlation coefficients 0.96 vs. 0.74) and in previous studies6. Both methods confirm the dominant role of the co-ignimbrite phase in the total bulk volume of the eruption. The amount of material deposited as fallout amongst experiments differed in less than 1.5%, a very consistent result. Method 1 simulated the dispersal of tephra (0.5 cm thick or larger) to be 15% smaller than Method 2, and 20% smaller than previous studies6. Figure 2. Model isopach maps showing the best-fit FALL3D tephra dispersal deposit (cm) for each phase of the CI super-eruption.  Tephra dispersal is shown for (a) the 44km high ultra-plinian plume accumulating a total of 54 km3 of fallout material; (b) the 38 km co-ignimbrite plume accounting for 74% of the total fallout material; (c) the combined Plinian and co-ignimbrite phases accumulating a total of 208 km3 of fallout material over ~3 million km2; (d) the classical single-phase approach for an eruption duration of 23h.  D. Density-current effects We find the density-driven transport to be dominant for the first hour with an effective spreading radial velocity of ~130 m/s and producing an umbrella cloud radius of ~100 km. Model results show the effect of the density-driven transport to be significant in proximal areas, where tephra deposition is 1.5-2 times higher NE from the source and up to 50% lower in the east Mediterranean region due to the wind direction. These values are lower than expected for an eruption of such a magnitude. This is due to the strong stratospheric wind velocity of ~90 m/s found at the transport height above the vent. IV. CONCLUSIONS We bring to light valuable new results and methods in reconstructing the 39 ky CI super-eruption, accounting for both Plinian and co-ignimbrite phases. Simulation results show tephra fallout predominantly originated from the co-ignimbrite clouds. Density-current processes would have been significant in proximal areas. However, tephra transport would have been primarily dominated by wind advection, most likely as a result of intense stratospheric winds corresponding to best-fit synoptic conditions. Ecosystem recovery would have required tens to thousands of years depending on the thickness, nature and distance from source of the tephra deposits.  We suggest that the eruption would have cause a demographic crash among modern human populations boosted by the impact of the synchronous Heinrich Event 4 and the attendant episode of glacial advance on land. Such crash would have favoured the persistence of the Neanderthals in the Iberian Peninsula and not their disappearance as previously thought.  ACKNOWLEDGMENT A.M. thanks the CASE visualization team at the BSC for their contribution to this work.    REFERENCES 1. Sparks, R. S. J., Wilson, L. & Hulme, G. Theoretical modeling of the generation, movement, and emplacement of pyroclastic flows by column collapse. J. Geophys. Res. Solid Earth 83, 1727–1739 (1978).  2. Engwell, S. L., Sparks, R. S. J. & Carey, S. Physical characteristics of tephra layers in the deep sea realm: the Campanian Ignimbrite eruption. Geol. Soc. London, Spec. Publ. 398, 47–64 (2014).  3. Fedele, F., Giaccio, B., Isala, R. & Orsi, G. The Campanian ignimbrite eruption, Heinrich event 4, and Palaeolithic change in Europe: a high-resolution investigation. In Volcanism and the Earth’s Atmosphere 139, 301–325 (American Geophysical Union, 2003).  4. Zilhão, J. Neandertals and moderns mixed, and it matters. Evol. Anthropol. 15, 183–195 (2006).  5. Costa, A., Macedonio, G. & Folch, A. A three-dimensional Eulerian model for transport and deposition of volcanic ashes. Earth Planet. Sci. Lett. 241, 634–647 (2006).  6. Costa, A. et al. Quantifying volcanic ash dispersal and impact of the Campanian Ignimbrite super-eruption. Geophys. Res. Lett. 39, L10310 (2012).  7. Costa, A., Folch, A. & Macedonio, G. Density-driven transport in the umbrella region of volcanic clouds : Implications for tephra dispersion models. Geophys. Res. Lett. 40, 4823–4827 (2013).  8. Sparks, R. S. J. & Walker, G. P. L. The significance of vitric-enriched air-fall ashes associated with crystal-enriched ignimbrites. J. Volcanol. Geotherm. Res. 2, 329–341 (1977).

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A Novel approach to reconstruct the plinian and co-ignimbrite phases of large eruptions - Campanian Ignimbrite

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