Response of faults to climate-driven changes in ice and water volumes on Earth’s surface

2010 ◽  
Vol 368 (1919) ◽  
pp. 2501-2517 ◽  
Author(s):  
Andrea Hampel ◽  
Ralf Hetzel ◽  
Georgios Maniatis
Keyword(s):  
Rate Increase ◽  
Numerical Models ◽  
Ice Sheets ◽  
Slip Rate ◽  
Normal Faults ◽  
Basin And Range Province ◽  
Ice Caps ◽  
Last Glaciation ◽  
Earthquake Frequency ◽  
Water Volumes

Numerical models including one or more faults in a rheologically stratified lithosphere show that climate-induced variations in ice and water volumes on Earth’s surface considerably affect the slip evolution of both thrust and normal faults. In general, the slip rate and hence the seismicity of a fault decreases during loading and increases during unloading. Here, we present several case studies to show that a postglacial slip rate increase occurred on faults worldwide in regions where ice caps and lakes decayed at the end of the last glaciation. Of note is that the postglacial amplification of seismicity was not restricted to the areas beneath the large Laurentide and Fennoscandian ice sheets but also occurred in regions affected by smaller ice caps or lakes, e.g. the Basin-and-Range Province. Our results do not only have important consequences for the interpretation of palaeoseismological records from faults in these regions but also for the evaluation of the future seismicity in regions currently affected by deglaciation like Greenland and Antarctica: shrinkage of the modern ice sheets owing to global warming may ultimately lead to an increase in earthquake frequency in these regions.

Antarctic Climate History and Global Climate Changes

2017 ◽  
Author(s):  
Pontus Lurcock ◽  
Fabio Florindo
Keyword(s):  
Ocean Circulation ◽  
Climate Changes ◽  
Numerical Models ◽  
Global Climate ◽  
Sediment Cores ◽  
Ice Sheets ◽  
Global Ocean ◽  
Climate History ◽  
Global Climate Changes ◽  
Planetary Albedo

Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.

Influence of viscous layers on the growth of normal faults: insights from experimental and numerical models

2003 ◽  
Vol 25 (9) ◽  
pp. 1471-1485 ◽  
Author(s):  
Nicolas Bellahsen ◽  
Jean-Marc Daniel ◽  
Laurent Bollinger ◽  
Evgenii Burov
Keyword(s):  
Numerical Models ◽  
Normal Faults

Modelling of interactions between dykes, inclined sheets and faults at Santorini volcano

2021 ◽  
Author(s):  
Kyriaki Drymoni ◽  
John Browning ◽  
Agust Gudmundsson
Keyword(s):  
Tensile Strength ◽  
Fault Zone ◽  
Numerical Models ◽  
Damage Zone ◽  
Sheet Thickness ◽  
Analytical Models ◽  
Energy Conditions ◽  
Dyke Swarm ◽  
Normal Faults ◽  
Santorini Volcano

<p>Dykes and inclined sheets are known occasionally to exploit faults as parts of their paths, but the conditions that allow this to happen are still not fully understood. Here we report field observations from a well-exposed dyke swarm of the Santorini volcano, Greece, that show dykes and inclined sheets deflected into faults and the results of analytical and numerical models to explain the conditions for deflection. The deflected dykes and sheets belong to a local swarm of 91 dyke/sheet segments that was emplaced in a highly heterogeneous and anisotropic host rock and partially cut by some regional faults and a series of historic caldera collapses, the caldera walls providing, excellent exposures of the structures. The numerical models focus on a normal-fault dipping 65° with a damage zone composed of parallel layers or zones of progressively more compliant rocks with increasing distance from the fault rupture plane. We model sheet-intrusions dipping from 0˚ to 90˚ and with overpressures of alternatively 1 MPa and 5 MPa, approaching the fault. We further tested the effects of changing (1) the sheet thickness, (2) the fault-zone thickness, (3) the fault-zone dip-dimension (height), and (4) the loading by, alternatively, regional extension and compression. We find that the stiffness of the fault core, where a compliant core characterises recently active fault zones, has pronounced effects on the orientation and magnitudes of the local stresses and, thereby, on the likelihood of dyke/sheet deflection into the fault zone. Similarly, the analytical models, focusing on the fault-zone tensile strength and energy conditions for dyke/sheet deflection, indicate that dykes/sheets are most likely to be deflected into and use steeply dipping recently active (zero tensile-strength) normal faults as parts of their paths.</p>

scholarly journals Nonequilibrium air clathrate hydrates in Antarctic ice: a paleopiezomdter for polar ice caps

1993 ◽  
Vol 90 (23) ◽  
pp. 11416-11418 ◽  
Author(s):  
H Craig ◽  
H Shoji ◽  
C C Langway
Keyword(s):  
Phase Boundary ◽  
Numerical Models ◽  
Equilibrium Phase ◽  
Vertical Displacement ◽  
Polar Ice ◽  
Ice Flow ◽  
Air Bubble ◽  
Ice Caps ◽  
General Parameter ◽  
Approximate Composition

"Craigite," the mixed-air clathrate hydrate found in polar ice caps below the depth of air-bubble stability, is a clathrate mixed crystal of approximate composition (N2O2).6H2O. Recent observations on the Byrd Station Antarctic core show that the air hydrate is present at a depth of 727 m, well above the predicted depth for the onset of hydrate stability. We propose that the air hydrate occurs some 100 m above the equilibrium phase boundary at Byrd Station because of "piezometry"--i.e., that the anomalous depth of hydrate occurrence is a relic of a previous greater equilibrium depth along the flow trajectory, followed by vertical advection of ice through the local phase-boundary depth. Flowline trajectories in the ice based on numerical models show that the required vertical displacement does indeed occur just upstream of Byrd Station. Air-hydrate piezometry can thus be used as a general parameter to study the details of ice flow in polar ice caps and the metastable persistence of the clathrate phase in regions of upwelling blue ice.

The last glaciation and sea level history of Fosheim Peninsula, Ellesmere Island, Canadian High Arctic

1996 ◽  
Vol 33 (7) ◽  
pp. 1075-1086 ◽  
Author(s):  
Trevor Bell
Keyword(s):  
High Arctic ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Ice Caps ◽  
Marine Deposits ◽  
Last Glaciation ◽  
Maximum Elevation ◽  
Glacier Runoff ◽  
History Of ◽  
Ice Conditions

The last glaciation of Fosheim Peninsula is reconstructed on the basis of landform and sediment mapping and associated radiocarbon dates. Ice growth involved the expansion of cirque glaciers and accumulation on upland surfaces that are now ice free. Limited ice buildup, despite lowering of the paleoglaciation level by 700–800 m, is attributed to the hyperaridity of the region during glacial conditions. Marine deposits in formerly submerged basins beyond the ice margins are interpreted to represent (i) sedimentation caused by local ice buildup and marine transgression by 10.6 ka BP, (ii) increased ablation and glacier runoff [Formula: see text]9.5 ka BP, and (iii) marine regression during the Holocene. Holocene marine limit reaches a maximum elevation of approximately 150 m asl along northern Eureka Sound and Greely Fiord and descends southeastwards to 139–142 m asl near the Sawtooth Mountains. A synchronous marine limit is implied where the last ice limit was inland of the sea. The magnitude and pattern of Holocene emergence cannot be fully explained by the glacioisostatic effects of the small ice load during the last glaciation of the region. Deglaciation of the peninsula was underway by 9.5 ka BP; however, local ice caps may have persisted through the wannest period of the Holocene until 6–5 ka BP. This was likely a function of reduced sea ice conditions and increased moisture availability which benefited low-lying coastal icefields, but had negligible effect on interior highland ice caps.

Late Pleistocene extension and strike-slip in the Dead Sea Basin

2004 ◽  
Vol 141 (5) ◽  
pp. 565-572 ◽  
Author(s):  
YUVAL BARTOV ◽  
AMIR SAGY
Keyword(s):  
Internal Structure ◽  
Slip Rate ◽  
Dead Sea ◽  
Strike Slip ◽  
Normal Faults ◽  
Small Scale ◽  
Dead Sea Basin ◽  
Pull Apart Basin ◽  
Western Border ◽  
The Dead

A newly discovered active small-scale pull-apart (Mor structure), located in the western part of the Dead Sea Basin, shows recent basin-parallel extension and strike-slip faulting, and offers a rare view of pull-apart internal structure. The Mor structure is bounded by N–S-trending strike-slip faults, and cross-cut by low-angle, E–W-trending normal faults. The geometry of this pull-apart suggests that displacement between the two stepped N–S strike-slip faults of the Mor structure is transferred by the extension associated with the normal faults. The continuing deformation in this structure is evident by the observation of at least three deformation episodes between 50 ka and present. The calculated sinistral slip-rate is 3.5 mm/yr over the last 30 000 years. This slip rate indicates that the Mor structure overlies the currently most active strike-slip fault within the western border of the Dead Sea pull-apart. The Mor structure is an example of a small pull-apart basin developed within a larger pull-apart. This type of hierarchy in pull-apart structures is an indication for their ongoing evolution.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

2020 ◽  
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need for re-examining the assumption of pre-determined frictional breakdown energy common in dynamic rupture modeling and for better understanding of the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

8. Glaciers of the past

2018 ◽  
pp. 146-152
Author(s):  
David J. A. Evans
Keyword(s):  
Numerical Models ◽  
Ice Core ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Aerial Imagery ◽  
The Past ◽  
Glacial Landforms

To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.

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