ORIGINAL RESEARCH PAPER

Flash-flood hyperpycnal flows generating shallow-water landslidesat Fiumara mouths in Western Messina Strait (Italy)

D. Casalbore • F. L. Chiocci • G. Scarascia Mugnozza •

P. Tommasi • A. Sposato

Received: 18 June 2010 / Accepted: 23 March 2011 / Published online: 12 April 2011

� Springer Science+Business Media B.V. 2011

Abstract On October 1, 2009, a small area along the

Sicilian coast between the villages of Scaletta Zanclea and

Giampilieri was struck by intense and concentrated rainfall

causing countless small landslides widespread over the

catchment area of steep subaerial creeks, locally known as

Fiumara. Dense and quick debris flows were channelized

within the Fiumara and destructively hit the villages and

entered the sea, where they likely transformed into hyper-

pycnal flows. The availability of pre- and post-flood high-

resolution bathymetry allows us to recognize the main

features and the most significant morphological variations

related to the impact of the flows on the seafloor. The

passage of hyperpycnal flows on the seafloor possibly

produced a suite of mass-wasting events, encompassing

sheet landslides (i.e. erosive scours), retrogressive slope

failure on loose sediment at the canyon headwall and rock-

falls on the conglomeratic bedrock along canyon sidewall.

The possible causes of these events are discussed on the

basis of available morphological evidence and geotechnical

considerations. Finally, the widespread occurrence of

mass-wasting features (i.e. submarine landslide scars)

morphologically similar to those generated by the 2009

flash flood allows us to hypothesize, from one side, a strong

correlation between this catastrophic event and the evolu-

tion of submarine canyons, and from the other side, the

possible use of these features for the assessment of flash-

flood occurrence.

Keywords Seafloor mapping � Bathymetric residual �Submarine instability � Hyperpycnal flow � Sicily

Introduction

Hyperpycnal flows are negatively buoyant flows that gravi-

tationally move on the seafloor because of their higher

density owing to suspended-sediment load with respect to

the standing water-body (Bates 1953). The river flood

material is thus transported directly to the continental slope

and eventually to the basin; as the flow initially contains fresh

water, its initiation and movement requires a high concen-

tration of suspended matter (Mulder and Syvitski 1995), so

that they are considered a sporadic geological process. These

phenomena have been reported during extreme events as

joukulhaups, lahars, dam breaking or in ‘‘dirty rivers’’, i.e.

small streams with torrential regime. The latter occur in arid

climates (i.e., North African ‘oueds’), after cyclones or

hurricanes (Californian and Mexican ‘arroyos’), in sub-gla-

cial fjords and in mid-latitude areas characterized by tectonic

uplift, as recently observed in some Appenines River (Mil-

liman and Syvitski 1992; Syvitski and Kettner 2007). Such

events commonly build coarse-grained fan-deltas at their

mouth (i.e., Prior and Bornhold 1989, 1990; Nava-Sanchez

et al. 1999; Gorsline et al. 2000; Sacchi et al. 2009). A similar

torrential regime also characterizes the ephemeral streams

developed in the mountainous relief facing the Messina

Strait, locally named Fiumara and characterized by a short

length (\20 km), extremely steep and high valley slopes,

and a flat and wide thalweg (Marchetti 2000; Sabato and

Tropeano 2004; Guarnieri and Pirrotta 2008). A braided

D. Casalbore (&) � P. Tommasi � A. Sposato

CNR, Istituto di Geologia Ambientale e Geoingegneria, Rome,

Via Salaria km 29.300, Monterotondo Stazione, 00016 Rome,

Italy

e-mail: daniele.casalbore@unibo.it

F. L. Chiocci � G. Scarascia Mugnozza

Dip. Scienze della Terra, University of Rome Sapienza,

P.le Aldo Moro 5, 00185 Rome, Italy

123

Mar Geophys Res (2011) 32:257–271

DOI 10.1007/s11001-011-9128-y

pattern and a gravelly bed load characterize the middle and

lower courses of these streams, indicating high-energy

hydraulic regime occurring during flash floods. The Fiumara

may thus represent a natural laboratory to study the offshore

effects of debris flows abruptly entering the sea.

On October 1, 2009, a small area between Scaletta

Zanclea and Giampilieri villages experienced intense and

concentrated rainfall that induced small-scale mass-wasting

events on the surrounding relief and flash flood within the

narrow and steep subaerial Fiumara (Ortolani 2009). Such

processes generated thick and quick debris flows that caused

casualties and severe damage to the human settlements on

the coast before entering the sea. The availability of pre-

flood high resolution bathymetry of the area led us to carry

out a post-event multibeam survey in order to investigate

possible seafloor variations due to the entrance of debris

flows into the sea. The aim of the paper is to show the effects

of the transit of subaerial debris flows into the marine realm

and discuss the presence and type of underwater morpho-

logical marks to define the main characters of the flood-

generated hyperpycnal flows and their related geo-hazard.

Data and methods

The two study areas are the immediate offshore of Scaletta

Zanclea and Giampilieri villages, in the southwestern part of

Messina Strait (Fig. 1), where two bathymetric surveys were

carried out between 2005 and 2007 using small vessel and

the R\V Universitatis (Table 1). Data were DGPS-posi-

tioned and acquired with multibeam systems operating at

different frequencies: Reson Seabat 8125 (455 kHz) for

shallow-water sectors (5–120 m bsl) and Reson Seabat 8160

(50 kHz) for deep-water sectors (100–2,000 m bsl), cover-

ing the entire Messina Strait. At the end of November 2009

(i.e., 58 days after the October 1, 2009, flash flood) a mul-

tibeam survey was carried out with Simrad EM710

(100 kHz) system onboard R\V Urania between 20 and

1,000 m bsl (Table 1) in the Sicilian side of Messina Strait.

For all the surveys, sound velocity profiles were acquired

daily within the investigation area, ‘‘ad hoc’’ calibration

lines were carried out at the start and end of the survey, and

redundant overlapping between swaths was applied. Mul-

tibeam data were processed with ‘‘non-standard’’ proce-

dures by using dedicated software (Caris Hips and Sips 6.1).

The processing can be divided into 7 stages that include:

(a) removal of spikes and signal drift from navigation;

(b) application of sound velocity profile in time stamp and

nearest distance mode; (c) calibration of sensor attitude and

application of tide gauge correction, (d) manual editing on

single swath for the first removal of the organized and non-

organized noise, (e) application of statistical and geometri-

cal filters on the whole dataset; (f) further editing of fake

sounding, mainly in the area of overlapping swaths and

(g) generation of a digital elevation model by using

weighted average. In shallow water sectors (\120 m bsl),

the obtained digital terrain models (DTMs) have a cell-size

of 1 m for both pre- and post-flood surveys, while in deep

water sectors, DTMs have a cell size of 10 and 5 m,

respectively. This implies that quantitative seafloor varia-

tions, obtained as difference between pre- and post-event

DTMs, are more reliable for shallow-water sectors, where

the resolution of the two DTMs is comparable (cell-size

1 m) and the precision of the data is higher (about ±1 m)

than those of deep-water sectors, where the cell size and

precision are about ±10 m. For the latter, only qualitative

indications were derived from residual maps. For the study

of the subaerial portion, high-resolution pre- and post-event

DTMs (cell size of 2 m) and aerial photographs (pixel res-

olution of 0.25 cm) were used to identify the main subaerial

mass-wasting features produced by the 1st October heavy

rainfall. This dataset was ground-truthed by numerous field

observations, whose results are not discussed in detail

because they are beyond the scope of this article. It is also

important to mention that there is a physical gap between the

subaerial DTM reaching sea level and the post-event

bathymetry reaching minimum water depth of 20 m bsl. In

this area, as wide as a few tens of meters, the data were

extrapolated even if it could be crucial for the initiation and

evolution of hyperpycnal flows.

Multibeam backscatter from the post-event cruise was

also processed in order to obtain qualitative information on

the sediment distribution at the seafloor and on the meso-

scale erosive-depositional features. Ten grab samples of

sediment were recovered on the most significant features

and backscatter zones in order to ground-truth geophysical

data (Table 2).

Bathymetric data also were used for preparing seafloor

morphology to be used in stability analyses of the shelf

margin at Scaletta Zanclea. Conventional limit equilibrium

(LE) analyses were performed in order to estimate the

shear strength mobilized during the failure highlighted by

the comparison of pre- and post-flood bathymetric surveys.

Subsequently, it was verified if the strength obtained so far

could be compatible with the strength that should be rea-

sonably provided by the shelf deposit assuming different

failure mechanisms.

For LE analyses, a 2D scheme was adopted, though it

should lead to a slight underestimation of mobilized strength.

However, approximations introduced by this procedure are

comparable to the indeterminations affecting the other

parameters of the analysis and the lack of specific geotech-

nical investigations. For the same reasons, to develop a

stress–strain model with a constitutive law appropriate for

granular materials would be too much sophisticated given

the preliminary character of the analysis.

258 Mar Geophys Res (2011) 32:257–271

123

Fig. 1 Shaded relief of Western Messina Strait, with the indication of

Scaletta Zanclea and Giampilieri villages, where devastating flash

floods occurred in October 2009. Subaerial digital terrain model from

SRTM data (cell size 90 m), bathymetry is from 2005 to 2007

multibeam surveys (cell size 10 m, Table 1). Yellow dashed lines

delimit the catchment basins of the main subaerial streams (Fiumara),

labeled as in Figs. 3 and 8 and Table 3. The lower inset shows three

representative bathymetric profiles of the Sicilian side of Messina

Strait (location in the main figure)

Table 1 Multibeam surveys carried out in the study area

Survey name Year Ship Multibeam Frequency

(Khz)

Depth

range (m)

Area of

survey (km2)

Days

MERC 2005 Universitatis Seabat 8160 50 100–2,000 400 8

MERC(2) 2007 Small boat Seabat 8125 455 5–120 60 3

BOB09 2009 Urania Simrad EM710 100 20–1,000 300 3

Mar Geophys Res (2011) 32:257–271 259

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Geological setting

The study area is located in the Messina Strait (Fig. 1), a

geologically active area characterized by complex geody-

namic processes which affect both the Calabrian Arc

compressive zone system and the Tyrrhenian extensional

tectonic system (Lentini et al. 1995; Scarfı et al. 2009 and

references therein). The Messina Strait is bounded by high-

angle normal faults with prevailing N–S to NE–SW

orientation, identified as active during Pliocene and Pleis-

tocene times (Ghisetti 1992). These structures are able to

generate frequent and strong earthquakes, such as the 1908

Reggio Calabria-Messina event (M 7.1) that caused more

than 70,000 casualties (Valensise and Pantosti 1992). The

seismic activity produced a devastating impact during the

last four centuries (Guidoboni et al. 1997), promoting the

formation of massive landslides, slumps, and liquefaction

of soil, as well as the deviation of watercourses (Bottari

et al. 1986; Murphy 1995; Galli 2000).

The area is characterized by rapid tectonic uplift (among

the fastest documented in Italy, Valensise and Pantosti 1992;

Catalano and De Guidi 2003) that produced mountainous

relief very close to the coast, with steep and short subaerial

valleys periodically affected by flash flooding (Guarnieri and

Pirrotta 2008). An average uplift rate of about 1 mm/y has

been estimated for the Sicilian coasts, affecting the hanging

wall of the main recognized seismogenic faults (Bonfiglio

and Violanti 1983; Catalano et al. 2003).

From an oceanographic point of view, the Messina Strait

is characterized by strong marine current and vortices,

known since ancient times (i.e., the two mythological

monsters Scylla and Charybdis in Homer’s Odyssey, 800

B.C.). Throughout the year, two water masses are

encountered in the Strait: the Tyrrhenian surface water

flowing to the south and the colder and saltier Levantine

Intermediate Water flowing from the Ionian Sea to the

north. Superimposed on these stationary currents are

the tidal currents originating from the co-oscillation of the

water masses of the Strait with the tides of the adjacent seas

(Casagrande et al. 2009 and references therein).

Data analysis

Pre-event setting: submarine morphology of the study

area

The physiography of the Strait is characterized by a major

central canyon (Messina Canyon, only partially visible in the

rightmost part of Fig. 1), trending roughly N–S, which is fed

by a large number of tributaries from the Calabrian and

Sicilian coasts. In particular, the Sicilian side of Messina

Strait can be divided into three morpho-bathymetric sectors.

The first sector, located between Messina and S. Margherita

Marina, is characterized by the lack of a continental shelf or

well-developed submarine depositional terrace, i.e., littoral

sediment accumulated below wave-base level on steep

coasts (sensu Chiocci and Orlando 1996; SDT in Fig. 1 and

profile 1); it is instead made up of a slope apron from the coast

down to 300–400 m bsl, evolving downslope in channelized

features. The second sector, between S. Margherita Marina

and Giampilieri, displays a narrow continental shelf, about

800 m wide in correspondence of a slope break located at

80 m bsl, incised by three canyons (Fig. 1 and profile 2). The

third sector, located between Giampilieri and Alı Terme

(Fig. 1 and profile 3), shows a narrow and discontinuous

submarine depositional terrace close to the coast (slope break

at 15–30 m bsl, SDT in Figs. 4 and 5), whose formation can

be related to the present sea-level highstand (\5 ka), as

proposed for similar features identified in the Italian conti-

nental margin (Chiocci et al. 2004). The terrace is cut by a

suite of about 500-m-spaced small canyons, most of them

directly facing the Fiumara mouths. Submarine canyons are

300–500 m wide, 1–1.5 km long, and a few tens of meters

deep; they are markedly erosive down to 300 m bsl where

elongated, low-relief fans are present, usually in

Table 2 Grab sample location

(see also Fig. 4c and 5c) and

depth; coordinates are in UTM-

WGS84-33 N

Grab sample Easting Northing Depth (m) Location

BB1 542,256 4,212,273 45 Giampilieri (shallow flash-flood deposits)

BB3 542,309 4,212,197 74 Giampilieri (shallow flash-flood deposits

BB4 542,340 4,212,144 90 Giampilieri (shallow flash-flood deposits)

BB5 542,374 4,212,075 118 Giampilieri (sidewall scar)

BB6 542,220 4,212,217 46 Giampilieri (canyon)

BB8 542,326 4,214,467 20 Giampilieri (blocky area)

BB9 541,389 4,211,193 27 Scaletta (minor scar)

BB10 541,228 4,211,121 21 Scaletta (main scar)

BB11 541,269 4,211,106 35 Scaletta (main scar)

BB12 541,363 4,211,068 63 Scaletta (landslide deposit)

BB14 541,476 4,211,015 85 Scaletta (minor scar)

260 Mar Geophys Res (2011) 32:257–271

123

correspondence with a decrease of the slope gradient below

10–12�. Canyon headwalls are made up of multiple coa-

lescing scars; in particular, 18 scars are recognized between

Ali Terme and Santa Margherita Marina.

At Scaletta Zanclea, the headwall of the canyon is located

at about 18 m bsl, 150 m offshore the coast, and its axis is

aligned with the corresponding Fiumara mouth (Fig. 4a).

The headwall is morphologically complex with an overall

semi-circular shape, about 350 m in diameter. In contrast, at

Giampilieri the headwall of the canyon shows a more elon-

gated and narrow shape; its axis is not aligned with the

present-day mouth of the Fiumara, which is located about

200 m to the north. A blocky fan-shaped area is present

between 8 and 25 m bsl offshore Fiumara mouth (Fig. 5a). The

Giampilieri Canyon is highly asymmetric, with the northern

side more rectilinear and steeper than the southern one.

Fig. 2 Cumulative rainfall recorded on October 1, 2009, at the 4 rain

gauge stations closest to the study area (location in the upper left insetof Fig. 1). In the inset, cumulative rainfall at the same rain gauge

stations from September 5 to October 5, 2009; data are from

www.regione.sicilia.it/presidenza/protezionecivile

Fig. 3 a Aerial photo of the

study area (location in Fig. 1),

with the limits of catchment

basin (labeled as in Figs. 1 and

8 and Table 3) and indication of

the main mass-wasting events

occurred during October 1,

2009. Three bathymetric

sections of the lower reach of

Fiumara Racinazzo are shown

in the left part of the figure,

gray areas represent the

sections where debris flows

flowed. b The delta generated

by the October 2009 flash flood

at Scaletta Zanclea, where

Fiumara Racinazzo debouches;

red shadow indicates the 4-m-

high railway wall that was

exposed before the flood and

was then partially buried by the

flash-flood delta. Dashed yellowline indicates the position of the

pre-event coastline

Mar Geophys Res (2011) 32:257–271 261

123

The slope of northern sidewall (45� to vertical) suggests the

outcropping of competent/cohesive material along its margin,

as also confirmed by ROV dives performed in the post-flood

survey (Fig. 6c). Arcuate scarps, parallel to the northern

sidewall, are also visible on the pre- and post-flood DTM

(minor scars in Fig. 5a). These features are some tens of

meters long and a few meters high, and they could be inter-

preted as landslide scarp or tension cracks.

The October 1, 2009 event

On October 1, 2009, the area between Scaletta Zanclea and

Giampilieri villages was struck by heavy rainfall that

generated slope failures and debris flows that caused 37

casualties and severe damage to the local settlements along

the coast (Ortolani 2009).

S. Stefano di Briga and Fiumedinisi rain gauge stations, a

few kilometers to the north and south of the study area,

recorded a cumulative rainfall of 225 and 150 mm between

4.00 p.m. and 10.00 p.m. on October 1st (Figs. 1 and 2,

Protezione Civile 2009), corresponding to an average

intensity of 30 mm/h. Actually, the rainfall intensity is likely

to have been much higher in the catchment basins upslope of

Scaletta Zanclea and Giampilieri villages. This is a conse-

quence of the extremely concentrated nature of the event,

owing to both local orographic and meteorological condi-

tions, as demonstrated, for instance, by the lower rainfall

amount recorded at the outermost rain gauges (Messina

and Antillo, Figs. 1 and 2). The higher occurrence of slope

failures and debris flows in the catchment basins upslope of

Scaletta Zanclea and Giampilieri villages with respect to the

surrounding sector may also be considered another evidence

of the higher rainfall intensity in the study area (Fig. 3a).

Finally, it should be noticed that the 1st October event fol-

lowed a period of intense precipitation. In the previous

2 weeks, a cumulative rainfall as high as about 300 mm was

recorded from rain gauge stations (inset in Fig. 2), which led

to a total precipitation of about 600 mm in the period

Fig. 4 Shaded relief (a) and

backscatter map (b) of the

Scaletta Canyon (location in

Fig. 1); bathymetry is from

2009 post-flood survey

(Table 1). High-backscatter

(HB) flow trail and belt,

interpreted as coarse-grained

flow deposits, are possibly

related to the October 2009

flash-flood deposits. In c, pre-

(black lines) and post-flood

contours (red lines), with the

main morphological features

generated by the gravity flows

in October 2009; the location of

ROV dives and grab sites (see

also Fig. 6 and Table 2) are also

shown. In d, map of residuals

(difference between pre- and

post-flood bathymetry), values

in the color scale bar are in

meters. Note that c and d refer

to the area in the box of a

262 Mar Geophys Res (2011) 32:257–271

123

between September 15 and October 1, corresponding to 60%

of the mean annual rainfall in the area.

Aerial photos before and after the October 1, 2009 event

and subaerial DTMs allowed us to recognize 500 slope

instabilities over an area of 18 km2 (Fig. 3a). The total soil

volume mobilized during and immediately after the rainfall

event for the Fiumara Racinazzo flowing to Scaletta

Zanclea and the Fiumara Giampilieri is estimated to be

about 140.000 and 400.000 m3, respectively.

The generated debris flows were characterized by a

mean concentration of the solid/water mixture of about

40–50% (A. Armanini pers. comm.), with an average unit

weight volume of 17 kN/m3 (Ortolani 2009), implying a

particle concentration of hundreds of kg per m3. The esti-

mated flow thickness and velocity at the mouths were

3–4 m and 10–20 m/s (Ortolani 2009), respectively. In the

Scaletta case, most of the velocity of the subaerial debris

flow was acquired in correspondence of the 50 m high

scarp recognizable in Profile 4 of Fig. 3, upslope from it

the flow was temporarily dammed and then inundated the

final section of the Fiumara. Along the coast, debris flows

generated lobate deltas with beach accretion and coastline

progradation of 4 and 50 m, respectively (Fig. 3b). These

features were partially dismantled during the successive

storms that commonly hit the Sicilian coast during the

winter months.

Fig. 5 Shaded relief (a) and

backscatter map (b) of the

Giampilieri Canyon (location in

Fig. 1), bathymetry is from

2009 multibeam survey

(Table 1). High-backscatter

(HB) belt, interpreted as coarse-

grained flow deposits, is

possibly related to the October

2009 flash-flood deposits. In c,

pre- (black lines) and post-flood

contours (red lines), where the

main morphological features

generated by the gravity flows

in October 2009; the location of

ROV dives and grab-sampling

sites (see also Fig. 6 and

Table 2) are also shown. In d,

map of residuals (difference

between pre- and post-flood

bathymetry), values in the colorscale bar are in meters. Note

that c and d refer to the area in

the box of a

Mar Geophys Res (2011) 32:257–271 263

123

Post-flood survey

The availability of multi-temporal bathymetric surveys for

the whole Sicilian coast of the Messina Strait, encom-

passing the area affected by the flood, allows us to define

the morphological variations produced by this catastrophic

event. In the investigated area, significant changes were

recorded only offshore of the mouth of Scaletta and

Giampilieri Fiumara, where positive and negative residuals

(i.e., seafloor accretion or erosion) were identified.

According to this evidence, we interpret all the significant

morphological variations occurred between 2005–2007 and

2009 surveys (Figs. 4 and 5) as being produced during or

immediately after the flood on October 1, 2009.

Fig. 6 Images of representative

ROV dives (upper 4 images)

and grab samples (lower 4

images) recovered in the study

area. a Homogenous sandy

seafloor with scattered

metamorphic clasts in the main

scar at the headwall of Scaletta

Canyon (R5a in Fig. 4); b tree

trunk transported by flash flood

in the upper part of Giampilieri

Canyon (R5b in Fig. 5);

c bedrock outcrops in

correspondence of the

Giampilieri Canyon sidewall

(R5c in Fig. 5); d meter-scale

blocks probably detached from

the upslope steep scarp (R5d in

Fig. 5). BB10 (e) and BB12

(f) samples are taken from the

main scar and landslide deposit

within the Scaletta Canyon

(location in Fig. 4c); they

recovered a gravelly sand

(BB10) and sand with a low

amount of sub-rounded

metamorphic clasts (BB12),

respectively. Samples BB1

(g) and BB5 (h) were taken

from the shallow flash-flood

deposits and sidewall scar in the

upper part of Giampilieri

Canyon, respectively (location

in Fig. 5c). BB1 recovered an

upper oxidized level

(10–20 mm thick) formed by

fine-grained material and

organic matter above a lowerthick dark level of coarse-

grained material with gravelly

clasts; BB5 recovered sand with

sub-rounded to angular

metamorphic clasts

264 Mar Geophys Res (2011) 32:257–271

123

Bathymetric residual at Scaletta Canyon

In the northwestern part of the Scaletta canyon, a semi-cir-

cular landslide scar is well recognizable on the map of

residuals (Figs. 4c, d). The scar has a diameter of about

130 m and extends over an area of 14,000 m2. The landslide

mobilized a volume of 65,000 m3, producing a maximum

excavation of about 15 m (Fig. 4d). The canyon headwall

retreated 50 m upslope, establishing its edge at about 14 m

bsl, 86 m offshore the coast. At the foot of the scar, a fan-

shaped accumulation zone is witnessed by a positive residual

(landslide deposits in Fig. 4c). It extends from 40 m bsl

down to 120 m bsl over an area of 17,000 m2, with a maxi-

mum thickness of 5 m and an estimated volume of

25,000 m3. Minor erosion rims the northeastern part of the

headwall, while a minor scar is recognizable further down-

slope, where it removed part of the landslide deposit (Fig. 4).

Two fan-shaped depositional features can be recognized in

the lower part of the Scaletta Canyon (indicated as flash flood

deposits in Fig. 4a) on the basis of morphological evidence

and comparison between pre- and post-flood contours. They

extend from 220 m bsl down to 500 m bsl, over a total area of

about 100 9 103 m2 with a thickness of several meters.

Within the canyon headwall, multibeam backscatter

imaging (Fig. 4b) shows the occurrence of several high-

backscatter flow trails, several meters wide and a few hun-

dred meters long. These flow trails merge downslope, giving

rise to a high-backscatter belt that matches the location of

the two fan-shaped depositional features (flash-flood

deposits in Fig. 4a). The high backscatter trails and belt are

interpreted as coarse-grained flow deposits. This is also

confirmed by direct observation (ROV dives, R5a in Figs. 4

and 6a) of gravelly and sandy seafloor in the main landslide

scar and by coarse-grained sand with several sub-centi-

metric or centimetric metamorphic angular clasts recovered

from the scar area (BB9, BB10, BB11 grab samples in

Figs. 4c and 6e). Sand with a small amount of sub-rounded

metamorphic gravel clasts was retrieved in the landslide

deposit (BB12 grab sample in Figs. 4c and 6f) and at the

headwall of a deeper scar (BB14 grab sample in Fig. 4c).

Bathymetric residual at Giampilieri Canyon

In the Giampilieri area (Fig. 5a) the setting is different with

respect to the Scaletta area, as the axis of the Giampilieri

Canyon is not aligned with the mouth of the Fiumara. After

entering the sea, the debris flow was likely transformed to

hyperpycnal fluxes that moved first over a span of shelf

relatively flat (about 5�) in front of the mouth and then

entered the canyon at the middle of the NE sidewall, which

is nearly sub-vertical. The result is an erosive trail on the

flat area, with erosive scours (Fig. 5c, d), each about 10 m

wide, 20–30 m long and 1–2 m deep. Where the flow

entered the canyon, a major landslide is present on the NE

canyon sidewall, extending also within the canyon thalweg.

This scar (sidewall scar in Fig. 5c) is few tens of meters

wide and 150 m long, and 5 m deep (Fig. 5d), corre-

sponding to a minimum volume of about 20,000 m3. In the

shallow-water area no relevant deposits are found, apart

from some infilling of depressed areas located within the

blocky facies in shallow water near the mouth (Fig. 5d). A

thin deposit is instead present from 25 to 100 m bsl in the

upper part of the Giampilieri canyon (indicated as shallow

flash-flood deposit in Fig. 5c); it covers an area of

5,000 m2 with a maximum thickness of 2 m for a total

estimated volume of 6,000 m3. The deposit seems to have

been partially removed by the sidewall landslide, on the

basis of their geometric relationship. Other fan-shaped

features can be recognized between 120 and 200 m bsl in

the central part of the canyon (deep flash-flood deposits in

Fig. 5a).

Two high-backscatter belts (Fig. 5b) were recognized in the

proximal part of the canyon, merging downslope in a larger belt

that matches the deep flash-flood deposits in Fig. 5a. These

features can be interpreted as coarse-grained flow deposits, as

also confirmed by direct observation made through ROV dives.

These latter also show the presence of: (a) tree trunks on the

seafloor (Fig. 6b), (b) partly cemented sand and cobble along

the sub-vertical canyon sidewall (Fig. 6c) and (c) meter-sized

blocks at the foot of the sidewall scar (Fig. 6d) that appear to be

detached from the sub-vertical slope.

Five grab samples labeled BB1, BB3, BB4, BB5, and

BB6 were taken in the Giampilieri Canyon and in sur-

rounding areas, while one sample (BB8) was taken at the

base of the blocky facies present on the shelf (Fig. 5c). In

the proximal part of the canyon thalweg, sample BB1

(Figs. 5c, 6 g) recovered first an oxidized layer (10–20 mm

thick) formed by fine-grained material and organic matter

mainly represented by plant fragments. Below, a thick dark

layer of coarse-grained material with gravelly clasts is

present. Sample BB6 (Fig. 5c), taken at the same water

depth as BB1 but outside the deposit, retrieved a 10-mm-

thick layer of sand and gravel with metamorphic clasts

overlying a fine-grained level. Samples BB4 and BB5

(Fig. 5c), taken from the scar, mainly recovered sand and

sub-rounded to angular metamorphic clasts. Sample BB8

(Fig. 5c), taken at the base of the blocky facies, recovered

fine sand with wood fragments.

Stability analyses of the failure at Scaletta Canyon

Two-dimension limit equilibrium back-analyses were per-

formed along a profile located on the central part of the

Scaletta slide scar (Fig. 4). The regular shape of the land-

slide scar, reconstructed by comparing pre- and post-slide

bathymetry, suggests that failure involved a nearly

Mar Geophys Res (2011) 32:257–271 265

123

homogeneous material, as also confirmed by seafloor

samples and observations conducted during ROV dives.

These considerations and the simple slope morphology

induced to analyze failure along circular surfaces. Actually

the selected circle is slightly shallower than that interpo-

lating the post-slide seafloor to account for some post-

failure erosion of the slide scar (Fig. 7a). However, similar

results were also obtained using a general surface closer to

the post-slide morphology.

Two series of analyses were conducted with different

hypotheses on applied stresses: (1) applying normal and

tangential stresses Drv and s to the seafloor exerted by the

debris/hyperpycnal flow running over the shelf; (2) in

addition to normal and shear stresses an excess pore

pressure Du was assumed within the soil mass corre-

sponding to the vertical stress induced by the debris/hyper-

pycnal flow body. In both cases a bulk weight of 18 kN/m3

for the terrace deposit was assumed, as it is made up of

coarse sand and gravel.

Even though Du actually depends on the complete state of

stress, assuming Du within the soil mass equal to the vertical

stress induced by the debris/hyperpycnal flow body could be

reasonable due to the small depth of the slip surface.

On the basis of the thickness (hdeb = 3 m) and sub-

merged unit weight of the debris (c0deb = 7 kN/m3) the

load per unit area Drv at the seabed upslope of the canyon

headwall should have been in the order of 10–15 kPa.

The flow could also have induced a shear stress at the

seafloor which can be considered to be equal to the yield

stress sy at the bottom of the debris flow (Fig. 7a). In this

respect, Lee and Locat (2004) report that for bouldery

debris flows in China a value of 2.5 kPa was measured for

a 3-m-thick flow. The same authors utilized sy equal to

5 kPa for the analysis of the Palos Verdes debris avalanche,

off the Southern California coast. While the loading foot-

print (Fig. 7a) extends well behind the slope crest, a

reduced extension was assumed downslope from it due to

the relevant dispersion of the debris flow after the slope

break. Negligible bottom shear stress due to hydroplaning

were assumed beneath the flow front (Mohrig et al. 1998).

Under hypothesis (1) (loading of debris/hyperpycnal

flow body in drained conditions), analyses yield a mobi-

lized angle of shear strength equal to 23� or 24� depending

on the value assumed for sy (2.5 kPa or 5 kPa). This angle

is too low compared to that of the drained strength enve-

lope of a coarse-grained loose deposit such as that forming

the depositional terrace at Scaletta.

Conversely, if the pore pressure induced by the load

exerted by the flow is not dissipated during the flow transit

and undrained conditions establish, as in hypothesis (2), the

mobilized shear strength angle u0m ranges between 25.5�and 26.5� depending on the pore pressure distribution. This

angle could be regarded as a rough estimate of the strength

mobilized at a flow failure. In order to verify if this

hypothesis is plausible, from the value of u0m the slope

tgw0L of the flow liquefaction surface FLS in the plane of

stress invariants p0-q (isotropic and deviatoric stress com-

ponents) was calculated (Fig. 7b). For an undrained shear

process, FLS separates stable from unstable conditions and

lies at a quite lower angle with respect to the drained

failure envelope. For clean sands consolidated under iso-

tropic conditions, Kramer (1996) suggests that tgw0L be

approximately two thirds of the drained strength envelope.

Under this assumption in our case the slope of the drained

strength envelope in the p0-q plane would correspond to a

drained shear strength angle range 38�–39�, which should

be not far from that of the failed sediments.

Discussion

Reconstruction of hyperpycnal flows and related mass-

wasting features

We associate all significant seafloor variations with the

entrance of subaerial debris flows into the sea, where they

Fig. 7 Simplified scheme a adopted for the stability analysis the of

submarine landslide occurred at the headwall of Scaletta Canyon (see

Fig. 4 and text for detail). Hdeb indicates the height of the subaerial

debris flows entering to the sea, c0deb is the submerged unit weight of

the debris flow. b Position in the plane of stress invariants of the flow

failure surface FLS, expressing undrained failure conditions in the

submerged slope, with respect to the steady state line (SSL) that

corresponds to the drained strength envelope (Kramer 1996)

266 Mar Geophys Res (2011) 32:257–271

123

are inferred to evolve to more turbulent hyperpycnal flows

downslope, as witnessed by the recognition of erosive

scours on the seafloor (Fig. 5, see below). The recognized

morphologies coupled with geological constraints have

been indirectly used to draw some hints on the behavior of

the flood-generated hyperpycnal flows. Morphological

features observed on the seafloor were linked to the fol-

lowing seafloor instabilities: (1) delamination; (2) slope

failure in loose material; (3) rock-fall in the bedrock along

canyon sidewalls.

Delamination, i.e., removal of sheet portions of a lay-

ered seafloor, was inferred from the presence of erosive

scours in the flat area offshore the Giampilieri Fiumara

mouth (Fig. 5). These erosive features can be related to the

strong shear stresses applied by the bottom of the dense

hyperpycnal flow, rich in coarse-grained fraction, on the

loose sandy seafloor. Similar features were recognized in

modern and ancient coarse-grained deltas, where they have

been interpreted as erosive flutes generated by turbulent

gravity flows (i.e., Prior and Bornhold 1989, 1990). The

alignment of the scours could thus mark the transition from

the subaqueous debris flow to more turbulent hyperpycnal

flow on the shelf before entering the Giampilieri Canyon.

Laboratory and field studies have demonstrated that sub-

aqueous debris flows can give rise to turbidity currents, as

their highly permeable front regions may be subject to high

dynamic stresses resulting in the entrainment of ambient

water that can cause the head region to dilate and break up

(e.g., Mohrig and Marr 2003; Elverhøi et al. 2005).

Moreover, the permeability of the coarse-grained mixture

within the body of the debris flow may give rise to the

production of a turbulent, overriding suspended-sediment

cloud as a consequence of elutriation of finer grains from

the flow surface (e.g., Mulder and Alexander 2001; Sohn

et al. 2002; Mohrig and Marr 2003).

The scar observed at the head of the Scaletta Canyon

could be related to a slope failure that occurred in a loose

coarse-grained sediment, forming the submarine deposi-

tional terrace. Failure should have been induced by the load

applied to the seafloor by the hyperpycnal flow (Fig. 7).

The most plausible triggering mechanism is represented by

an abrupt increase in pore pressure owing to the sudden

loading exerted on the seafloor by the debris flow running

over the upper section of the slope. The hypothesis is

legitimated by the high propagation velocity of the flow (on

the order of 10–20 m/s), which implies that such a stress

increase was applied in a short time interval to a large area,

thus avoiding a dissipation of the excess pore pressure

(undrained conditions). A similar process was, for instance,

hypothesized in coarse-grained fan deltas developed within

the fjords of British Columbia (Prior and Bornhold 1989),

and also in the Fraser River delta (Christian 1998). The

bottle-neck shape of the landslide scar also suggests that

failure was accompanied by fluidization, as it is often

recognized in loose granular materials. A further insight in

the mechanical properties of the terrace deposit is, how-

ever, necessary in order to quantitatively assess its attitude

to liquefaction. This could be obtained through a combi-

nation of in situ tests and laboratory undrained triaxial tests

on samples reconstituted at the relative density determined

in situ.

The landslide in the Giampilieri Canyon sidewall

involved a much more resistant material, as the sub-vertical

scarps made up of moderately cemented sand and cobble

demonstrate (Fig. 6c). Moreover, the presence at the foot

of the sidewall scar of meter sized blocks (Fig. 6d), that

likely detached from the upslope steep scarp, suggests a

block slump or a toppling mechanism. The slope instability

was possibly triggered by the undercutting of the canyon

sidewall generated by a plunging flux entering the canyon

from the upslope terrace. The steepness of the canyon

sidewall, the presence of small scars along it, and the

tension cracks observed behind the canyon edge in the pre-

flood survey indicate that the slope was prone to instability

before the flood event.

The role of hyperpycnal flow in the evolution of small

canyons and related geo-hazard implication

South of Giampilieri, the seafloor is furrowed by many

small and closely-spaced canyons. Their morphology,

characterized by a relatively uniform width and a flat floor,

is similar (apart from the size) to that of channels formed

by hyperpycnal flows in other submarine settings, such as

the California Continental borderland (Piper and Normark

2001), the head of Laurentian Fan (Mosher and Piper

2007), the Scotian continental slope (Piper et al. 2007) and

the area offshore of the Tet River (Bourrin et al. 2008).

The key role played by flood-generated hyperpycnal

flows in the formation of canyons is also testified to by the

strict correspondence between the location of Fiumara

mouths and submarine canyons (9 cases on 13, Fig. 8 and

Table 3) as well as by the similarity in the width of the

subaerial Fiumara mouth and that of the submarine chan-

nels (Fig. 9a, Table 3). Similar observations are also

reported in recent studies of modern sandy deltas (i.e.,

Mitchell 2005; Brucker et al. 2007), implying that the

width of hyperpycnal flow channels should be related to the

discharge of a hyperpycnal flood (Piper and Normark

2009). However, it is noteworthy that the scatter plot of the

canyon width versus the catchment area of the Fiumara,

which could be used as a proxy for the discharge of a flash

flood, shows a lack of correlation between the two vari-

ables (Fig. 9b), suggesting that volume or total discharge is

not a controlling factor for the development of the sub-

marine channel. Conversely, the attention should be

Mar Geophys Res (2011) 32:257–271 267

123

focused on the amount of sediment load in the flash flood to

generate a debris flow, which transforms into hyperpycnal

flows when entering the sea. The debris flows generated

within the Racinazzo catchment basin, indeed, produced a

significant impact on the Scaletta village and the Scaletta

Canyon headwall, whereas the more diluted flows gener-

ated in the nearby Divieto catchment basin did not produce

any significant changes in seafloor morphology. An

Table 3 Main morphometric

parameters of submarine canyon

and associated Fiumara(numbered as in Fig. 1)

a Fiumara width refers to the

cross-section measured at its

mouth on a terrestrial DTM

Canyon

name

Progressive

distance

along coast (m)

Distance from

the coast (m)

Width

(m)

Associated

Fiumara

Widtha

(m)

Fiumara

catchment

basin (km2)

1 600 280 175 a 160 1.1

2 1,250 205 200 b 190 0.7

3 1,887 193 210 No No No

4 2,326 100 320 c 300 6.1

5 3,104 128 185 d 174 0.5

6 3,830 80 170 e(Scaletta) 160 1.3

7 4,130 202 140 f 125 0.8

8 4,600 124 190 No No No

9 5,400 160 210 g(Giampilieri) 220 8.8

10 6,000 435 165 No No No

11 6,400 430 140 No No No

12 7,000 330 230 h 250 6.2

13 8,050 75 123 i 140 2

Fig. 8 Relationship between catchment basin of subaerial Fiumara(brown bar, labeled as in Figs. 1 and 3 and Table 3) and submarine

canyons (blue bar, numbered as in Table 3); distance from the coast

and width of canyons and mouths are to scale (for numerical value

refer to Table 3). AT Alı Terme, SC Scaletta Zanclea, GI Giampilieri,

SM S. Margherita Marina

268 Mar Geophys Res (2011) 32:257–271

123

exhaustive explanation of the relation between total dis-

charge and capability to generate debris flow in the study

area is, however, beyond the scope of this paper.

We can, however, hypothesize that other ‘‘marine’’

processes may have a role in controlling canyon formation

and evolution. The steepness and high sedimentation rates

of this continental margin act, in fact, as predisposing

factors for the development of small-scale instabilities. The

frequent occurrence of medium and large earthquakes in

the area, recorded by the CFTI-Med 4.0 database (Guido-

boni et al. 1997), could obviously represent a main trig-

gering of small-scale submarine instabilities as well as the

cyclic loading by storm-waves (i.e., Locat and Lee 2002

and references therein). Once a canyon is formed, however,

the occurrence of hyperpycnal flows in shallow water may

increase instability and force the canyon to reach the

coastline through retrogressive failures, as confirmed by

the scar generated at the headwall of the Scaletta Canyon

during the 1st October flood. This is the reason why even

though not all canyons are found in front of the Fiumara

mouths, all Fiumara mouths face submarine canyons

(Fig. 8 and Table 1). In this regard, the elongated shape of

submarine canyons with a flat floor that terminate upslope

with a well-defined headwall is thought to be typical of

channels developed through successive retrogressive fail-

ures (Mosher et al. 2004; Casalbore et al. 2010).

A final consideration regards the widespread recognition

in the study area of scar morphologies similar to that

generated by the flash flood at Scaletta Canyon headwall.

Each of them has a volume of some hundreds of cubic

meters, 5–10 times higher than the volume mobilized by

the October 1, 2009, landslide (65,000 m3). Therefore, if

we hypothesize that each major scar is the result of 5–10

landslides similar to the October 1, 2009 event, we may

assume for statistical purposes the occurrence of 90–180

landslides in the last 5 ky, i.e., one landslide every

25–50 years in a sector of coast as long as 5.5 km, or one

landslide each km every 125–250 years. This high fre-

quency of submarine landslide is similar to that observed in

other geologically active areas (i.e., Gulf of Corinth,

Lykousis et al. 2007) and raises an important question

about the geo-hazard related to these processes.

Conclusion

The present study shows the effect of flash-flood and debris

flows that recently (October 1, 2009) devastated the

Giampilieri and Scaletta Zanclea villages in Italy on the

submarine environment. The recognition of different mass-

wasting features, their comparison with other similar fea-

tures elsewhere, have allowed the reconstruction of a suite

of genetically-linked processes that influence the evolution

of the canyon heads here present. The recognized mass-

wasting features encompass erosive scours due to the

flowing of hyperpycnal flows on low gradient seafloor,

retrogressive slope failure that evolved in fluidized flows at

the canyon headwall, rockfalls and topples at the canyon

sidewall. These results allow us to link flash-flood gener-

ated debris that can evolve in hyperpycnal flow through a

progressive water entrainment in the flowing mass to the

occurrence of shallow-water submarine landslides. Sedi-

mentation rate, cyclic loading of storm-waves, and ground

acceleration due to earthquakes must also play an impor-

tant role, and the weighting of each predisposing or trig-

gering factor is a changeling scientific goal for future work.

More generally, the research highlights that repeated

multibeam surveys are a fundamental tool in geologically

active marine areas, because they depict even small-scale

events and allow a quantitative estimate of erosion and

deposition created by fast-occurring processes that other-

wise cannot be detected. Through morphometric analysis

and geological consideration we are able to hypothesize

Fig. 9 Width of submarine canyons plotted against width of facing

subaerial Fiumara mouths (a) and against their catchment basin;

b numerical values are reported in Table 3. Note the strong

correlation between the two variables in the left plot (R2 = 0.93)

Mar Geophys Res (2011) 32:257–271 269

123

the frequency of instability events in the studied span of

margin to be on the order of one landslide each km every

125–250 years. The understanding of the stability condi-

tions of a submarine slope and consequently a reliable

geo-hazard definition should rely on more detailed study of

single failure events and in situ geotechnical investigations,

but such studies are expensive and often not feasible.

Seafloor mapping and multi-temporal surveys may thus

represent a first step toward a geo-hazard assessment,

allowing the identification of the most dangerous areas,

where monitoring activities should concentrate.

Acknowledgments Crews of the R/V Urania and Universitatis are

gratefully acknowledged along with researchers and students partici-

pating the surveys as well as Vigili del Fuoco and Dipartimento per la

Protezione Civile Nazionale. In particular Captain Vincenzo Lubrano,

thanks to his ability and goodwill, was able to sail the 60 m long Urania

Vessel close to the coast, allowing the complete reconstruction of the

mass-wasting features produced in shallow water. Two anonymous

reviewers and the guest editor A. Cattaneo are acknowledged for useful

suggestions that greatly improved the quality of the paper. The study is

part of the MaGIC project (www.magicproject.it). Some figures were

realized through the use of Global Mapper v.10.

References

Bates CC (1953) Rational theory of delta formation. Am Assoc Petrol

Geol Bull 37(9):2119–2162

Bonfiglio L, Violanti D (1983) Prima segnalazione di Tirreniano ed

evoluzione pleistocenica del Capo Peloro (Sicilia nord-orien-

tale). Geogr Fis Dinam Quat 6:3–15

Bottari A, Carapezza E, Carapezza M, Carveni P, Cefali F, Lo

Giudice E, Pandolfo C (1986) The 1908 Messina Strait

earthquake in the regional geostructural framework. J Geodyn

5:275–302

Bourrin F, Durrieu de Madron X, Heussner S, Estournel C (2008)

Impact of winter dense water formation on shelf sediment

erosion (evidence from the Gulf of Lions NW Mediterranean).

Cont Shelf Res 28:1984–1999

Brucker S, Hughes Clarke JE, Beaudoin J, Lessels C, Czotter K,

Loschiavo R, Iwanowska K, Hill P (2007) Monitoring flood-

related change in bathymetry and sediment distribution over the

Squamish Delta, Howe Sound, British Columbia: United States

Hydrographic Conference 2007, Norfolk, Virginia

Casagrande G, Warn Varnas A, Stephan Y, Folegot T (2009) Genesis

of the coupling of internal wave modes in the Strait of Messina.

J Marine Syst 78:191–204

Casalbore D, Romagnoli C, Chiocci FL, Frezza V (2010) Morpho-

sedimentary characteristics of the volcaniclastic apron around

Stromboli volcano (Italy). Mar Geol 269:132–148

Catalano S, De Guidi G (2003) Late Quaternary uplift of northeastern

Sicily: relation with the active normal faulting deformation.

J Geodyn 36:445–467

Catalano S, De Guidi G, Monaco C, Tortorici G, Tortorici L (2003)

Long-term behaviour of the late Quaternary normal faults in the

Strait of Messina area (Calabrian arc): structural and morpho-

logical constraints. Quaternary International 101–102:81–91

Chiocci FL, Orlando L (1996) Lowstand terraces on Tyrrhenian Sea

steep continental slopes. Mar Geol 134:127–143

Chiocci FL, D’Angelo S, Romagnoli C, Ricci Lucchi F (2004)

Memorie descrittive della Carta Geologica d’Italia—Atlante dei

Terrazzi Deposizionali Sommersi lungo le coste italiane vol 58

Christian HA (1998) Seismic liquefaction potential of the southwest-

ern Fraser River delta margin. In Clague JJ, Luternauer JL,

Mosher DC (eds) Geology and natural hazards of the Fraser

River Delta, British Columbia, vol 525. Geological Survey of

Canada Bulletin, pp 231–240

Elverhøi A, Issler D, De Blasio FV, Ilstad T, Harbitz CB, Gauer P

(2005) Emerging insights into the dynamics of submarine debris

flows. Nat Haz Earth Syst Sci 5:633–648

Galli P (2000) New empirical relationships between magnitude and

distance for liquefaction. Tectonophysics 324:169–187

Ghisetti F (1992) Fault parameters in the Messina Strait (southern

Italy) and relations with the seismogenic source. Tectonophysics

210:117–133

Gorsline DS, de Diego T, Nava-Sanchez EH (2000) Seismically

triggered turbidites in small margin basins: Alfonso Basin,

Western Gulf of California and Santa Monica Basin, California

Borderland. Sed Geol 135:21–35

Guarnieri P, Pirrotta C (2008) The response of drainage basins to the

late Quaternary tectonics in the Sicilian side of the Messina

Strait (NE Sicily). Geomorphol 95:260–273

Guidoboni E, Ferrari G, Mariotti D, Comastri A, Tarabusi G,

Valensise G (1997) Catalogue of strong earthquakes in Italy 461

b.c.–1997 and Mediterranean area 760 b.c.–1500. An advanced

laboratory of historical seismology. http://storing.ingv.it/cfti4

med. Accessed 3 March 2011

Kramer S (1996) Geotechnical earthquake engineering. Prentice Hall,

Upper Saddle River

Lee HJ, Locat J (2004) Mobilization of submarine flows: examples

and questions. In: Picarelli L (ed) Occurrence and mechanisms

of flow-like landslides in natural slopes and earthfills. Patron

Editore, Bologna, pp 273–287

Lentini F, Carbone S, Catalano S, Grasso M (1995) Principali

lineamenti strutturali della sicilia nord-orientale. Studi Geologici

Camerti, volume speciale, 1995/2

Locat J, Lee HJ (2002) Submarine landslides: advances and

challenges. Can Geotech J 39:193–212

Lykousis V, Sakellariou D, Rousakis G, Alexandri S, Kaberi H,

Nomikou P, Georgiou P and Balas D (2007) Sediment failure

processes in active grabens: the Western Gulf Of Corinth

(Greece). In Lykousis V, Sakellariou D, Locat J (eds) Submarine

mass movements and their consequences, 3rd international

symposium, pp 297–305

Marchetti M (2000) Geomorfologia fluviale, Pitagora editrice,

Bologna, p 230

Milliman JD, Syvitski JPM (1992) Geomorphic/tectonic control of

sediment discharge to the ocean: the importance of small

mountainous rivers. J Geol 100:525–544

Mitchell NC (2005) Channelled erosion through a marine dump site

of dredge spoils at the mouth of the Puyallup River, Washington

State, USA. Mar Geol 220:131–151

Mohrig D, Marr JG (2003) Constraining the efficiency of turbidity

current generation from submarine debris flows and slides using

laboratory experiments. Mar Petrol Geol 20:883–899

Mohrig D, Whipple K, Hondzo M, Ellis C, Parker G (1998) Hydroplaning

of subaqueous debris flows. GSA Bulletin 110:387–394

Mosher DC, Piper DJW (2007) Analysis of multibeam seafloor

imagery of the Laurentian Fan and the 1929 Grand Banks

landslide area. In: Lykousis V, Sakellariou D, Locat J (eds)

Submarine mass movements and their consequences, 3rd inter-

national symposium, pp 77–88

Mosher DC, Piper DJW, Campbell DC, Jenner K (2004) Near

surfacegeology and sediment-failure geohazards of the central

Scotian Slope. Am Assoc Petrol Geol Bull 88:703–723

Mulder T, Alexander J (2001) The physical character of subaqueous

sedimentary density flows and their deposits. Sedimentology 48:

269–299

270 Mar Geophys Res (2011) 32:257–271

123

Mulder T, Syvitski JPM (1995) Turbidity currents generated at mouths

of rivers during exceptional discharges to the world oceans. J Geol

103:285–299

Murphy W (1995) The geomorphological controls on seismically

triggered landslides during the 1908 Straits of Messina earth-

quake, Southern Italy. Q J Eng Geol Hydrogeol 28:61–74. doi:

10.1144/GSL.QJEGH.1995.028.P1.06

Nava-Sanchez EH, Gorsline DS, Cruz-Orozco R, Godinez-Orta L

(1999) The El Coyote fan delta: a wave-dominated example

from the Gulf of California, Mexico. Quat Int 56:129–140

Ortolani (2009) Alluvione di Messina del 1� ottobre 2009. Le colate

rapide di fango e detriti hanno devastato il territorio, le fiumare

hanno retto. Geoitalia 29:31–36. www.geoitalia.org

Piper DJ, Normark WR (2001) Sandy fans—from Amazon to

Hueneme and beyond. Am Assoc Petrol Geol Bull 85:

1407–1438

Piper DJW, Normark W (2009) Processes that initiate turbidity

currents and their influence on turbidites: a marine geology

perspective. J Sediment Res 79:347–362

Piper DJW, Shaw J, Skene KI (2007) Stratigraphic and sedimento-

logical evidence for late Wisconsinan subglacial outburst floods

to Laurentian Fan. Palaeogeogr Palaeoclimatol Palaeoecol 246:

101–119

Prior DP, Bornhold BD (1989) Submarine sedimentation on a

developing Holocene fan delta. Sedimentology 36:1053–1076

Prior DP, Bornhold BD (1990) The underwater development of

Holocene fan deltas. In: Colella A, Prior DB (eds) Coarse grained

deltas, vol 10. Int. Assoc. Sediment. Spec. Publ., pp 75–90

Protezione Civile (2009) Emergenza colate di fango nel territorio

della provincia di Messina, Italia. http://www.regione.sicilia.

it/presidenza/protezionecivile/documenti/messina2009/Relazion

edescrittivaFSUE_MESSINA.pdf. Accessed 3 March 2011

Sabato L, Tropeano M (2004) Fiumara: a kind of high hazard river.

Phys Chem Earth 29:707–715

Sacchi M, Molisso F, Violante C, Esposito E, Insinga D, Lubritto C,

Porfido S, Toth T (2009) Insights into flood-dominated fan-

deltas: very high-resolution seismic examples off the Amalfi

cliffed coasts, eastern Tyrrhenian Sea. In Violante (ed) Geohaz-

ard in Rocky Coastal Areas, vol 322. Geological Society,

London, pp 33–71 (special publications)

Scarfı L, Langer H, Scaltrito A (2009) Seismicity, seismotectonics

and crustal velocity structure of the Messina Strait (Italy). Phys

Earth Plan Int 177:65–78

Sohn YK, Choe MY, Jo HR (2002) Transition from debris flow to

hyperconcentrated flow in a submarine channel (the Cretaceous

Cerro Toro Formation, southern Chile). Terra Nova 14:405–415

Syvitski JPM, Kettner AJ (2007) On the flux of water and sediment

into the northern Adriatic Sea. Cont Shelf Res 27:296–308

Valensise G, Pantosti D (1992) A 125 kyr-long geological record of

seismic source repeatability: the Messina Strait (southern Italy)

and the 1908 earthquake (Ms 71/2). Terra Nova 4:472–483

Mar Geophys Res (2011) 32:257–271 271

123