Seismogenic, electrically conductive, and fluid zones at continental plate boundaries in New Zealand, Himalaya, and California

Jiracek, George R.; González, Víctor; Caldwell, T. G.; Wannamaker, Philip E.; Kilb, Debi

doi:10.1029/175gm18

Cited by 29 publications

(39 citation statements)

References 99 publications

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“…High fluid pressures may make the fault extremely weak, possibly permitting patches of the deep fault to deform by brittle rather than ductile failure, and support localized slip on the deep extension of the SAF (Shelly 2010). Localized deformation in the ductile deformation region is possible where strain softening occurs and water-weakening is one mechanism to facilitate this (Jiracek et al 2007). Thus, tremor occurrences provide several indirect indications for the existence of a fluid source at tremor source depth.…”

Section: Crustal Fluid Source and Indications For Mantle-derived Fluidsmentioning

confidence: 99%

“…At these temperatures the electrical conductivity of sea water is approximately ten times higher than at room temperatures (Quist and Marshall 1968). These include fracture interconnectivity, grain-edge interconnectivity or both (Jiracek et al 2007). In addition, peremability must be maintained over time, either by con-tinous deformation, permeability-enhancing reactions or high fluid pressures, or a combination of these mechanisms (Jiracek et al 2007;Cox 2005).…”

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confidence: 99%

“…These include fracture interconnectivity, grain-edge interconnectivity or both (Jiracek et al 2007). In addition, peremability must be maintained over time, either by con-tinous deformation, permeability-enhancing reactions or high fluid pressures, or a combination of these mechanisms (Jiracek et al 2007;Cox 2005). Long-lasting deformation can generate interconnection on long distance ranges.…”

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confidence: 99%

“…MT cannot distinguish between permeability structure in actively deforming zones and maintained permeability formed in previously active zones. Only small strain rates, perhaps in combination with other mechansims, are required to maintain permeability in a ductile deformation regime, once developed (Jiracek et al 2007). Thus, the HCZ likely represents a ductile deformation region with maintained hydraulic permeability.…”

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confidence: 99%

“…Gürer and Bayrak (2007) formations, thereby facilitating mechanical failure and actively triggering seismicity or earthquakes within critically stressed regions (Jiracek et al 2007). …”

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confidence: 99%

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Magnetotelluric Studies at the San Andreas Fault Zone: Implications for the Role of Fluids

Becken

Ritter

2011

Surv Geophys

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Fluids residing in interconnected porosity networks have a significant weakening effect on rheology of rocks and can strongly influence deformation along fault zones. The magnetotelluric (MT) technqiue is sensitive to interconnected fluid networks, and can image these zones on crustal and upper mantle scales. MT has imaged several prominent electrically conductive anomalies at the San Andreas fault which have been attributed to the presence of saline fluids within such networks, and which have been associated with tectonic processes. These models suggest that ongoing fluid release in the upper mantle and lower crust is closely related to the mechanical state of the crust. Where fluids are drained into the brittle portion of the crust, and where these fluids are kept at high pressures, fault creep is supported. In response to fluid flux from deeper levels in combination with meteoric and crustal metamorphic fluid supply, and in response to fault creep, high-conductivity zones develop as fault zone conductors in the brittle portion of crust. In turn, the absence of crustal fluid pathays may be characteristic for mechanically locked segments. MT models suggest that those fluids are trapped at depth and kept at high pressures. It is speculated that fluids may infiltrate neighbouring rocks and induce non-volcanic tremor. MT has imaged several prominent electrically conductive anomalies at the San Andreas fault which have been attributed to the presence of saline fluids within such networks, and which have been associated with tectonic processes. These models suggest that ongoing fluid release in the upper mantle and lower crust is closely related to the mechanical state of the crust. Where fluids are drained into the brittle portion of the crust, and where these fluids are kept at high pressures, strain provides a means to develop and maintain permeability structure, and thus electrical conductivity, within the damage zone. Accordingly, these conductivity models played an important role in pin-pointing the SAFOD drilling location near Parkfield. *abstractClick here to download abstract: abstract.txt Surv. Geophys. manuscript No.In this paper, we consider MT studies at the SAF near Hollister and Carrizo The SAF has also been a target for telluric (Madden et al. 1993;Park et al. 2007) and magnetotelluric monitoring (e.g. Kappler et al. 2010). These installations attempted to monitor long-term electric (and magnetic) field variations of internal origin due to resistivity variations assiciated with earthquakes, large scale fluid flow or other causes. To date, it was not possible to identify significant field variations which can be attributed to tectonic processes. In this paper, we don't discuss details of this issue. 7The main objective of this paper is to review the MT results from the SAF in combination with other geophysical, geological and geochemical data and models in order to address fluid-related processes and their potential implications on the geodynamic setting, active tectonic processes and the mechanical ...

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Section: Crustal Fluid Source and Indications For Mantle-derived Fluidsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Gürer and Bayrak (2007) formations, thereby facilitating mechanical failure and actively triggering seismicity or earthquakes within critically stressed regions (Jiracek et al 2007). …”

mentioning

confidence: 99%

See 3 more Smart Citations

Magnetotelluric Studies at the San Andreas Fault Zone: Implications for the Role of Fluids

Becken

Ritter

2011

Surv Geophys

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Role of deep crustal fluids in the genesis of intraplate earthquakes in the Kachchh region, northwestern India

Kumar

Mahesh

Nagar

et al. 2017

Geophysical Research Letters

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Fluids play a prominent role in the genesis of earthquakes, particularly in intraplate settings. In this study, we present evidence for a highly heterogeneous nature of electrical conductivity in the crust and uppermost mantle beneath the Kachchh rift basin of northwestern India, which is host to large, deadly intraplate earthquakes. We interpret our results of high conductive zones inferred from magnetotelluric and 3‐D local earthquake tomography investigations in terms of a fluid reservoir in the upper mantle. The South Wagad Fault (SWF) imaged as a near‐vertical north dipping low resistivity zone traversing the entire crust and an elongated south dipping conductor demarcating the North Wagad Fault (NWF) serve as conduits for fluid flow from the reservoir to the middle to lower crustal depths. Importantly, the epicentral zone of the 2001 main shock is characterized as a fluid saturated zone at the rooting of NWF onto the SWF.

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Crustal Exhumation of Plutonic and Metamorphic Rocks: Constraints from Fission-Track Thermochronology

Baldwin

Fitzgerald

Malusà

2018

Springer Textbooks in Earth Sciences, Geography and Environment

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Seismogenic, electrically conductive, and fluid zones at continental plate boundaries in New Zealand, Himalaya, and California

Cited by 29 publications

References 99 publications

Magnetotelluric Studies at the San Andreas Fault Zone: Implications for the Role of Fluids

Magnetotelluric Studies at the San Andreas Fault Zone: Implications for the Role of Fluids

Role of deep crustal fluids in the genesis of intraplate earthquakes in the Kachchh region, northwestern India

Crustal Exhumation of Plutonic and Metamorphic Rocks: Constraints from Fission-Track Thermochronology

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