Thermal Constraints on Earthquake Depths in California

Bonner, Jessie L.

doi:10.1785/0120030041

Cited by 79 publications

(66 citation statements)

References 69 publications

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“…The event depths go down to ∼ 13 km there. Bonner et al (2003) report a statistical correlation between heat flow and seismic depths by comparing two separate high-resolution data sets in California. According to this, seismic depths of ∼ 15 km imply heat flow of ∼ 100 mW m −2 or less, and are in general agreement with the results of this study.…”

Section: Heat Flow Versus Maximum Depth Of Seismicity In Western Anatmentioning

confidence: 99%

“…Determination of the conductive heat flow near the surface of the earth has many important applications, such as understanding the recent history of plate tectonic activity Blackwell, 2008, 2009), determining the depth of brittle/ductile transition in the crust (Bonner et al, 2003), and estimating the geothermal energy potential of a region (Tester et al, 2006;Serpen et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Geothermal investigations in western Anatolia using equilibrium temperatures from shallow boreholes

Erkan

2015

Solid Earth

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Abstract. Determination of the conductive heat flow in western Anatolia has broad implications in many areas, including studies on the present-day extensional tectonic activity and assessments of the geothermal resources in the region. In this study, high-resolution equilibrium temperatures from 113 boreholes with depths of ∼ 100 m were analyzed for determination of the conductive heat flow. Thermal conductivities were either determined by measurements on outcrops or estimated using lithologic records. By a detailed analysis of temperature-depth curves, a total of 55 sites were selected as being useful for further conductive gradient/heat flow calculations, while the remaining 58 sites were abandoned due to hydrological effects on temperatures. Heat flow values with formal errors were calculated for 24 sites where rock thermal conductivity information is available. Due to the shallow depths of the investigated boreholes and uncertainties in thermal conductivity information, the results include a large accumulated error. A preliminary heat flow map is generated using the results of this study and a previous study in the southern Marmara region. is not observed in the region. The heat flow values reported in this study are comparable to the previously reported values in the Aegean Sea, as the two regions form the back-arc section of the Hellenic subduction zone.

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Section: Heat Flow Versus Maximum Depth Of Seismicity In Western Anatmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geothermal investigations in western Anatolia using equilibrium temperatures from shallow boreholes

Erkan

2015

Solid Earth

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“…We eliminated events with more than 2 km hypocenter location error and show only the well-located events in Figure 2. Bonner et al [2003] discussed the reliability of the hypocenter determination in the earthquake catalogs in California by comparing them with results of detailed local 3D studies and concluded that the systematic depth error between generic catalog models and local models are generally less than 1 km.…”

Section: à2mentioning

confidence: 99%

“…[15] Maximum depth of seismicity is related to the brittleto-ductile transition in the crust and is highly dependent on the crustal temperatures [e.g., Sibson, 1982;Chen and Molnar, 1983;Bonner et al, 2003]. California is a unique region to compare seismic cut-out depth with surface heat flow as both proxies are abundant and high quality.…”

Section: à2mentioning

confidence: 99%

“…California is a unique region to compare seismic cut-out depth with surface heat flow as both proxies are abundant and high quality. To compare the two data sets, we delimited the maximum depths of earthquakes by dashed lines in Figure 2 using a confidence interval of $95% [Bonner et al, 2003]. We also assumed that the depth of brittle-ductile transition should be represented by a smooth function in places where there is not enough seismicity to define the transition.…”

Section: à2mentioning

confidence: 99%

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Transient thermal regimes in the Sierra Nevada and Baja California extinct outer arcs following the cessation of Farallon subduction

Erkan

Blackwell

2009

J. Geophys. Res.

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[1] We examine the thermal relaxation of the Sierra Nevada and Baja California extinct outer arc blocks following the progressive cessation of Farallon subduction under western North America beginning at $30 Ma. Being parts of the same outer arc until the inland jump of the San Andreas transform fault at $5 Ma, these two regions show many similarities in their geology, geomorphology, rigid body behavior, and their relatively low seismicity. In the thermal model, we combine results of different geophysical and geophysical studies to constrain the thermal state and geometry of the outer arcs before the cessation of subduction and then model the postsubduction temperature responses in these regions using the results of the tectonic reconstructions. A well-constrained regional thermal model of these blocks using the results of many earlier studies in these regions confirms that the present low heat flow values in these regions are the remnants of the very cold outer arc thermal regime of the subduction zone even as long as 30 Ma after cessation of subduction. Thus the entire Pacific boundary of the North American plate is still in a transient thermal state. The calculated low lithospheric temperatures in the Sierra Nevada and Peninsular blocks correlate very well with their rigid body behavior obtained from geodetic studies, and seismogenic layer thicknesses obtained from seismological studies. This is in contrast with the fact that both regions are surrounded by intense deformation associated with the western North America intraplate and extraplate motions. These low-temperature islands play important roles in the present interaction of the North American and Pacific plates and contribute to the broad deformation of the transform boundary. The thermal relaxation of the extinct outer arcs includes both vertical heating from the underlying asthenosphere and the lateral heating from the extinct back arc (Basin and Range), which has remained as a high heat flow region after the cessation of the subduction. We suggest that the significant lateral heat transfer from the Basin and Range in the Sierra Nevada (and from the Gulf of California spreading center in the Peninsular block since $5 Ma) may be the main driving mechanism of the postsubduction volcanism/magmatism along the extinct volcanic arc and the recent tilted uplift of the Sierra Nevada block. The low lithospheric temperatures in Sierra Nevada region may also explain the observation of the high seismic velocities in the mantle beneath the southern Sierra Nevada where the downwelling of the mantle lithosphere proposed.

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Assessing long‐term postseismic deformation following the M7.2 4 April 2010, El Mayor‐Cucapah earthquake with implications for lithospheric rheology in the Salton Trough

et al. 2015

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The 4 April 2010 M w 7.2 El Mayor-Cucapah (EMC) earthquake provides the best opportunity to date to study the lithospheric response to a large (>M6) magnitude earthquake in the Salton Trough region through analysis of Global Positioning System (GPS) data. In conjunction with the EarthScope Plate Boundary Observatory (PBO), we installed six new continuous GPS stations in the months following the EMC earthquake to increase station coverage in the epicentral region of northern Baja California, Mexico. We modeled the pre-EMC deformation field using available campaign and continuous GPS data for southern California and northern Baja California and inferred a pre-EMC secular rate at each new station location. Through direct comparison of the pre-and post-EMC secular rates, we calculate long-term changes associated with viscoelastic relaxation in the Salton Trough region. We fit these velocity changes using numerical models employing an elastic upper crustal layer underlain by a viscoelastic lower crustal layer and a mantle half-space. Forward models that produce the smallest weighted sum of squared residuals have an upper mantle viscosity in the range 4-6 × 1018 Pa s and a less well-resolved lower crustal viscosity in the range 2 × 10 19 to 1 × 10 22 Pa s. A high-viscosity lower crust, despite high heat flow in the Salton Trough region, is inconsistent with felsic composition and might suggest accretion of mafic lower crust associated with crustal spreading obscured by thick sedimentary cover.

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Thermal Constraints on Earthquake Depths in California

Cited by 79 publications

References 69 publications

Geothermal investigations in western Anatolia using equilibrium temperatures from shallow boreholes

Geothermal investigations in western Anatolia using equilibrium temperatures from shallow boreholes

Transient thermal regimes in the Sierra Nevada and Baja California extinct outer arcs following the cessation of Farallon subduction

Assessing long‐term postseismic deformation following the M7.2 4 April 2010, El Mayor‐Cucapah earthquake with implications for lithospheric rheology in the Salton Trough

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