Seismotectonic and paleoseismic analyses using karst sediments

Forti, Paolo; Postpischl, D.

doi:10.1016/0025-3227(84)90138-5

Cited by 37 publications

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“…A change in trend of the growth axis of stalagmites, and occasionally stalactites, where the youngest layers (or laminae ) maintain alignments with the vertical direction (Figure d), defines a third class. The deviation of the growth axis of a speleothem from the vertical can be associated to several sources including cave flooding by ice or water (e.g., Jaillet et al, ), but in regions of vigorous seismic activity like the Apennines, the most likely cause (Forti & Postpischl, ) is coherent tilt of the concretion and of its bedrock (Becker et al, ). Such a tilt would imply either a low ground shaking, not able to cause speleothem collapse, or a substantial component of creep.…”

Section: Methodsmentioning

confidence: 99%

“…The analysis of speleothem deformation, such as breakage and collapse and offset of growth axis, is part of speleoseismological studies, which seek evidence of past earthquake within the cave archives (Becker et al, , ; Forti, ). Radiometric dating of the deformation (“speleoseismic”) events can be compared to historical seismicity catalogues (e.g.,Forti & Postpischl, ; Postpischl et al, ) or be used to extend back in time the paleoseismological record (e.g., Becker et al, ; Delaby, ; Gilli & Delange, ; Kagan et al, ; Lemeille et al, ; Perez‐Lopez et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…The underlying idea is based on the stalactite‐stalagmite oscillatory system, which represents the vertical datum. If other sources (landslide, flooding, ice flow, and animal or anthropic passage) of deformation can be excluded, the deviation of the growth axis from the vertical, and the speleothem breakage, are evidence for tilting and faulting of the block hosting the cave and for shaking of the cavity walls, respectively (Forti & Postpischl, ; Kagan et al, ). However, the difficulty in quantitative modeling of the observed deformation and its direct attribution to a seismogenic source remains a major issue (Becker et al, ; Lacave et al, ; Pons‐Branchu et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Speleoseismological Constraints on Ground Shaking Threshold and Seismogenic Sources in the Pollino Range (Calabria, Southern Italy)

Ferranti¹,

Martinelli

Valentini

et al. 2019

JGR Solid Earth

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Speleoseismological research carried out in the Pollino Range (Calabria, southern Italy), an area of alleged seismic gap in the active extensional belt running along the Southern Apennines, has placed constraints on the recurrence of M > 6 earthquakes, on the expected ground shaking threshold and on definition of seismogenic sources in the region. Radiometric (U-Th, AMS-14 C, and bulk-14 C) dating of before and after deformation layers from collapsed or tilted cave speleothems indicates that six speleoseismic events have occurred in the area during the last~42 ka, with a mean recurrence of~5.6 ka. Based on the in situ measured geometry and laboratory determined mechanical properties of speleothems and using an ad hoc seismogenic source model for northern Calabria, which involved both normal and strike-slip faults, we evaluate the seismic hazard at the cave sites. The numerical models to compute the ground horizontal acceleration threshold for speleothem failure was tested against intact and currently growing stalactites. The inferred age of these stalactites calibrated using established average speleothem growth rates of 0.3-1.2 cm/ka, ranges from~0.7 to~10 ka, with most of them younger than~5.6 ka. Results show that the~0.8-to 1.0-g peak ground acceleration threshold estimated for collapsed speleothems every 5.6 ka was achieved during strong (M > 6) and close (epicentral distance < 12 km) earthquakes. Considering a mean speleoseismic event recurrence of 5.6 ka and that no speleoseismic shaking has occurred in the last 5.5 ka, the probability of occurrence of an M > 6 event in the area in the next few centuries is quite high.Plain Language Summary Seismic shaking can cause collapse or tilt of cave speleothems (stalactites and stalagmites) and dating the calcite layers immediately after and before the deformation provides the age of unknown prehistorical earthquakes. By dating collapsed and tilted speleothems from the Pollino Range (Calabria, southern Italy), we built a catalog of six speleoseismic events that occurred in the last~42 ka in the area. We defined a seismic hazard model for the cave sites using known or newly proposed seismic sources. The model was tested against an estimate of the vulnerability to seismic shaking for several unbroken and currently forming stalactites based on their geometry (slender speleothems are more vulnerable) and their mechanical properties measured in laboratory. Results indicate that a peak ground acceleration threshold of~1 g for speleothem collapse because of strong (M > 6) and close (distance <12 km from the main seismogenic sources) is reached every 5.6 ka and is in agreement with the age of unbroken speleothems (<10 ka, mostly <5.6 ka). Considering a mean speleoseismic event recurrence of 5.6 ka and that no speleoseismic shaking has occurred in the last 5.5 ka, an M > 6 event in the area is pending in the next few centuries.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Speleoseismological Constraints on Ground Shaking Threshold and Seismogenic Sources in the Pollino Range (Calabria, Southern Italy)

Ferranti¹,

Martinelli

Valentini

et al. 2019

JGR Solid Earth

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“…This evidence includes broken speleothems and fallen stalactites (e.g., Postpischl et al, 1991;Ferranti et al, 1997;Lemeille et al, 1999;Delaby, 2001;Kagan et al, 2005;Šebela, 2008;Panno et al, 2009;Bábek et al, 2015;Méjean et al, 2015), blocks and ceiling collapses (e.g., Gilli, 1999;Pérez-López et al, 2009), deformed cave sediments and fault displacements (e.g., Gilli et al, 2010;Bábek et al, 2015), and speleothem growth anomalies (e.g., Forti et al, 1981;Forti and Postpischl, 1984;Akgöz and Eren, 2015;Rajendran et al, 2015). Although direct observations of cave damages immediately after an earthquake have rarely been observed, "seismothems" (i.e., speleothems potentially broken, or deformed, by a seismic…”

Section: Introductionmentioning

confidence: 99%

“…A few speleotectonic studies have been conducted in the high seismically active region of the Apennines (Forti and Postpischl, 1984;Postpischl et al, 1991;Ferranti et al, 1997Ferranti et al, , 2015. We performed a geological-structural field study, with a paleoseismological approach, in the Cavallone Cave located within the Maiella Massif, in the eastern Central Apennines (Fig.…”

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confidence: 99%

Defining a mid-Holocene earthquake through speleoseismological and independent data: implications for the outer Central Apennines (Italy) seismotectonic framework

Domenica

Pizzi

2017

Solid Earth

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Abstract. A speleoseismological study has been conducted in the Cavallone Cave, located in the easternmost carbonate sector of the Central Apennines (Maiella Massif), in a seismically active region interposed between the post-orogenic extensional domain, to the west, and the contractional one, to the east. The occurrence of active "silent normal faults", to the west, close to blind thrusts, to the east, raises critical questions about the seismic hazard for this transitional zone. Large collapses of cave ceilings, fractures, broken speleothems with new re-growing stalagmites on their top, preferential orientation of fallen stalagmites and the absence of thin and long concretions have been observed in many portions of the karst conduit. This may indicate that the cave suffered sudden deformation events likely linked to the occurrence of past strong earthquakes. Radiocarbon dating and, above all, the robust correspondence with other coeval on-fault and off-fault geological data collected in surrounding areas outside the cave, provide important constraints for the individuation of a mid-Holocene paleoearthquake around 4.6-4.8 kyr BP. On the basis of the available paleoseismological data, possible seismogenic sources can be identified with the Sulmona normal fault and other active normal fault segments along its southern prosecution, which recorded synchronous strong paleoevents. Although the correlation between speleotectonic observations and quantitative modeling is disputed, studies on possible effects of earthquake on karstic landforms and features, when corroborated by independent data collected outside caves, can provide a useful contribution in discovering past earthquakes.

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2007

Karst Hydrogeology and Geomorphology

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Seismotectonic and paleoseismic analyses using karst sediments

Cited by 37 publications

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Speleoseismological Constraints on Ground Shaking Threshold and Seismogenic Sources in the Pollino Range (Calabria, Southern Italy)

Speleoseismological Constraints on Ground Shaking Threshold and Seismogenic Sources in the Pollino Range (Calabria, Southern Italy)

Defining a mid-Holocene earthquake through speleoseismological and independent data: implications for the outer Central Apennines (Italy) seismotectonic framework

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