The geometry of the Wadati-Benioff zone under southern Central America and its tectonic significance: results from a high-resolution local seismographic network

Protti, Marino; ̈ndel, Federico Gu; McNally, Karen

doi:10.1016/0031-9201(94)90046-9

Cited by 134 publications

(160 citation statements)

References 30 publications

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“…At the southeastern terminus of the regional study, near the Costa Rica-Panama border, (located toward the lower right region of map in Figure 10), values are most reduced, including events both along the MAT and along shallow thrusts along the back arc. At this locale the failed Cocos ridge subducts [e.g., Protti et al, 1994], potentially increasing local high-frequency attenuation. Alternatively, because the rate of convergence gradually increases to the southeast from 70 to approximately 100 mm yr −1 [DeMets, 2001], there may be a modest increase in fault maturity due to increased cumulative slip, thus allowing for reduced t a [Choy and Kirby, 2004;Schorlemmer et al, 2005;Choy and Boatwright, 2009].…”

Section: Regional Resultsmentioning

confidence: 99%

Global evaluation of large earthquake energy from 1997 through mid-2010

Convers

Newman

2011

J. Geophys. Res.

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[1] We develop an updated radiated seismic energy E catalog of global earthquakes with seismic moment M 0 ≥ 10 19 Nm (M W ≥ 6.7) from 1997 through mid-2010, recording 342 events using 17849 seismograms. Station-specific corrections and event duration-dependent total P wave group calculations allow for improved E determinations for large-and long-duration earthquakes. We find the global mean energy-to-moment ratio = log 10 (E/M 0 ) = −4.59 ± 0.36. Robust deviations are found for thrust ( T = −4.74), strike-slip ( SS = −4.44), and normal ( N = −4.51) faulting events. For two regions with recent energy deficient tsunami earthquakes (TsE), we examine all large thrust earthquakes with M 0 ≥ 5 × 10 17 Nm (M W ≥ 5.7), to identify a regional characterization in their relative radiated energy-to-moment ratio. While thrust events along Java, Indonesia, the site of two TsE events in 1994 and 2006, are comparable ( T−JV = −4.91) to the global thrust average, events along the Middle America Trench (MAT), the site of the 1992 Nicaragua TsE, are consistently deficient ( T−MAT = −5.15). Along the MAT, a trend of increased deficiency in radiated energy to the southeast occurs in the direction of more rapid plate convergence. Global thrust mechanisms become increasingly deficient in radiated seismic energy at shallow depths, with TsE events representing the shallowest and most energetically deficient end-member of the events in the study. Results suggest thrust events are highly variable but tend to increase in apparent stress from about 15 kPa near the surface to 2 MPa near 70 km depth.

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Section: Regional Resultsmentioning

confidence: 99%

Global evaluation of large earthquake energy from 1997 through mid-2010

Convers

Newman

2011

J. Geophys. Res.

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“…The seismically active slab dips ~65° near the Nicaraguan border and shallows by a few degrees inboard of the Cocos Ridge. At depths below 60 km there is no seismically defined slab landward of the Cocos Ridge (Vergara Muñoz, 1988;Protti et al, 1994). …”

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confidence: 99%

Expedition 344 summary

Li¹,

Malinverno²,

Torres³

et al. 2013

Proceedings of the IODP

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Expedition 344 summaryProc. IODP | Volume 344 2 from velocity-strengthening to velocity-weakening friction, and shear becomes localized. The onset of seismogenic behavior is correlated with the intersection of the 100°-150°C isotherm and the subduction thrust (Hyndman et al., 1997;Oleskevich et al., 1999). With increasing depth down the subduction thrust, the frictional characteristics undergo a second transition either due to the juxtaposition with the forearc mantle or because the rocks are heated to 350°-450°C and can no longer store elastic stresses needed for rupture. Transitional regions between the three zones have conditional stability and can host rupture but are generally not thought to be regions where large earthquakes initiate.Although this three-zone two-dimensional view of the subduction thrust provides a reasonable framework, it is simplistic. Rupture models for large subduction earthquakes suggest significant fault plane heterogeneity in slip and moment release that in three dimensions is characterized as patchiness (Bilek and Lay, 2002). Additionally, we now know the transition zone from stable to unstable sliding is not simple but hosts a range of fault behaviors that includes creep events, strain transients, slow and silent earthquakes, and low-frequency earthquakes (Peng and Gomberg, 2010;Beroza and Ide, 2011;Ide, 2012).Fundamentally unknown are the processes that change fault behavior from stable sliding to stick-slip behavior. Understanding these processes is important for understanding earthquakes, the mechanics of slip, and rupture dynamics. For a fault to undergo unstable slip, fault rocks must have the ability to store elastic strain, be velocity weakening, and have sufficient stiffness. Hypotheses for mechanisms leading to the transition between stable and unstable slip invoke temperature, pressure, and strain-activated processes that lead to downdip changes in the mechanical properties of rocks. These transitions are also sensitive to fault zone composition, lithology, fabric, and fluid pressures.The composition of the material in the fault zone and its contrast with the surrounding wall rock play a key role in rock frictional behavior. The frictional state of the incoming sediment changes progressively with increasing temperature and pressure as it travels downdip. Important lithologic factors influencing friction are composition, fabric, texture, and cementation of rocks, as well as fluid pore pressure (Bernabé et al., 1992;Moore and Saffer, 2001;Beeler, 2007;Marone and Saffer, 2007;Collettini et al., 2009). For example, fault rocks with high phyllosilicate content are generally weaker than rocks with low phyllosilicate content (Ikari et al., 2011). Sediment properties including porosity, permeability, consolidation state, and alteration history also exert a strong influence on fault zone behavior. At erosive margins, where the plate boundary cuts into the overriding plate, the composition and strength of the upper plate is also important (McCaffrey, 1993).Field observations and la...

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“…Along the Middle America Trench, offshore the western margin of Costa Rica, the oceanic Cocos plate is subducting beneath the Caribbean plate at a convergence rate of 70 to 90 mm/year, forming the southern end of the Middle America Trench (Protti et al 1994;DeMets, 2001; Figure 1a). The Cocos plate subducting beneath Costa Rica was formed at two different spreading centers, the East Pacific Rise (EPR) and the Cocos-Nazca spreading center (CNS), and has been significantly influenced by Galapagos hotspot volcanism (von Huene et al 2000;Barckhausen et al 2001).…”

Section: Geological Settingmentioning

confidence: 99%

“…The location of shallow earthquakes along the plate interface varies along strike: earthquakes occur shallower and closer to the trench in the CNS crust than in the EPR crust (Protti et al 1994;Newman et al 2002). In June 2002, a Mw 6.4 earthquake occurred at a depth as shallow as~9 km along the Costa Rica margin offshore the Osa Peninsula (Arroyo et al 2009).…”

Section: Geological Settingmentioning

confidence: 99%

Frictional properties of sediments entering the Costa Rica subduction zone offshore the Osa Peninsula: implications for fault slip in shallow subduction zones

et al. 2014

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We examined the frictional properties of sediments on the Cocos plate offshore the Osa Peninsula, Costa Rica, and explored variations in the intrinsic frictional properties of the sediment inputs to the Costa Rica subduction zone. Sediment samples were collected at Site U1381A during the Integrated Ocean Drilling Program Expedition 334, and include hemipelagic clay to silty clay material (Unit I) and pelagic silicic to calcareous ooze (Unit II). The frictional properties of the samples were tested at a normal stress of 5 MPa under water-saturated conditions and with slip velocities ranging from 0.0028 to 2.8 mm/s for up to 340 mm of displacement. The experimental results reveal that the steady-state friction coefficient values of clay to silty clay samples are as low as~0.2, whereas those of silicic to calcareous ooze samples are as high as 0.6 to 0.8. The clay to silty clay samples show a positive dependence of friction on velocity for all tested slip velocities. In contrast, the silicic to calcareous ooze samples show a negative dependence of friction on velocity at velocities of 0.0028 to 0.28 mm/s and either neutral or positive dependence at velocities higher than 0.28 mm/s. Given the low frictional coefficient values observed for the clay to silty clay samples of Unit I, the décollement at the Costa Rica Seismogenesis Project transect offshore the Osa Peninsula likely initiates in Unit I and is initially very weak. In addition, the velocity-strengthening behavior of the clay to silty clay suggests that faults in the very shallow portion of the Costa Rica subduction zone are stable and thus behave as creeping segments. In contrast, the velocity-weakening behavior of the silicic to calcareous ooze favors unstable slip along faults. The shallow seismicity occurred at a depth as shallow as~9 km along the Costa Rica margin offshore the Osa Peninsula (M w 6.4, June 2002), indicating that materials characterized by velocity-weakening behavior constitute the fault zone at the depth of the seismicity. Fault slip nucleating along a fault in Unit II would be a likely candidate for the source of the shallow earthquake event.

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The geometry of the Wadati-Benioff zone under southern Central America and its tectonic significance: results from a high-resolution local seismographic network

Cited by 134 publications

References 30 publications

Global evaluation of large earthquake energy from 1997 through mid-2010

Global evaluation of large earthquake energy from 1997 through mid-2010

Expedition 344 summary

Frictional properties of sediments entering the Costa Rica subduction zone offshore the Osa Peninsula: implications for fault slip in shallow subduction zones

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