Mechanism and spatial distribution of Chilean earthquakes with relation to subduction of the oceanic plate

Stauder, William

doi:10.1029/jb078i023p05033

Cited by 226 publications

(108 citation statements)

References 20 publications

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“…In northern and central Peru (2"S-15"s) and in central Chili (27"S-33"S), the slab is marked by a dip of 5"-lo", whereas the other segments show a dip of about 25"-30" (Isacks and Molnar, 1971;Stauder, 1973Stauder, , 1975Barazangui and Isacks, 1976). The vertical cross section of shallow seismicity drawn around 5"s shows the first kilometers of the Benioff zone along the margin (Fig.…”

Section: Distonce From Trench Axis (Km)mentioning

confidence: 99%

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

et al. 1995

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A mega-submarine slide was evidenced along the Peruvian margin during a Seabeam survey of the R/V Charcot (Bourgois et al., 1986). The debris-slide was initially interpreted as the result of the slope failure occurring along a seaward curved scarp, and extending from east to west, along the line of maximum slope. Complementary bathymetric data obtained from the R/V Sonne survey conducted to the north and to the south of the previous surveyed area has resulted in the identification of large-scale polyphase submarine slides involving a total surface of about 1000 km', between latitudes 5"lSS and 6"05'S. Using Seabeam and Hydrosweep multibeam echosounder data in combination with deep-sea submersible observations, three distinct slope-failure types related to three main stages have been revealed. The three sliding phases occurred roughly along the same trend, orientated N230", and are therefore mainly controlled by the N80" orientation of the subducting Nazca plate.( 1) The first phase of slope failure is documented by a debris-avalanche deposit, which extends from the lower slope down to 5 km within the trench floor. The deposit originates from the northern wall of a wide valley located along the upper slope. (2) The second phase of slope failure is characterized by a debris-avalanche, with a crescent-shaped scar, located along the middle slope and a hummocky deposit covering the lower slope and extending up to 10 km across the trench. The volume of rock involved in this event is estimated to some 250 km3. The slope failure is assumed to be related to an oversteepening of the middle slope induced by a rollover deformation. (3) The third phase of slope failure corresponds to a translational sliding block and a toppling block with volumes of 6 km3 and 13 km3, respectively. The seismic energy produced during the seismic cycle has greatly increased fracturation and fluids buildup along the area previously weakened by a rollover fold. A restricted N-S folding is observed in the vicinity of the trench, to the north of the two debris-avalanche deposits. It may have formed in relation to the local compression limited to the subduction of the Nazca plate. Sliding and folding thus document the paradox between the compressive regime in the lower plate and the extensional regime in the upper part of the upper plate. IntroductionMost of the large-scale submarine landslides recognised worldwide occur either along intraplate volcanic alignments or along active continental margins. They include landslides along the steep submerged volcanic slopes of the Hawaiian islands (Lipman et al., 1988;Moore et al., 1989), the large landslides from Tristan da Cunha (South Atlantic island) and from El Hierro (Canary islands) described by Holcomb and Searle (1991), the volcanic debris-avalanche along the submerged flank of the Fournaise volcano off the Reunion island (L&at et al., 1989;Cochonat et al., 1990), the giant submarine slide on the northern slope of Puerto Rico island and the giant submarine slump along the northern Chile co...

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Section: Distonce From Trench Axis (Km)mentioning

confidence: 99%

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

et al. 1995

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“…Typical focal mechanism solutions for shallow earthquakes are of the thrust type with the direction of relative plate motion about N800E (STAUDER, 1973). The maximum dimensions of rupture zones of large South American earthquakes vary considerably along the strike of the active seismic zone.…”

Section: (D) South Americamentioning

confidence: 99%

Seismic Gaps and Plate Tectonics: Seismic Potential for Major Boundaries

McCann

Nishenko

Sykes

et al. 1979

Earthquake Prediction and Seismicity Patterns

149

201

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-The theory of plate tectonics provides a basic framework for evaluating the potential for future great earthquakes to occur along major plate boundaries. Along most of the transform and convergent plate boundaries considered in this paper, the majority of seismic slip occurs during large earthquakes, i.e., those of magnitude 7 or greater. The concepts that rupture zones, as delineated by aftershocks, tend to abut rather than overlap, and large events occur in regions with histories of both long-and short-term seismic quiescence are used in this paper to delineate major seismic gaps.In detail, however, the distribution of large shallow earthquakes along convergent plate margins is not always consistent with a simple model derived from plate tectonics. Certain plate boundaries, for example, appear in the long term to be nearly aseismic with respect to large earthquakes. The identification of specific tectonic regimes, as defined by dip of the inclined seismic zone, the presence or absence of aseismic ridges and seamounts on the downgoing lithospheric plate, the age contrast between the overthrust and underthrust plates, and the presence or absence of back-arc spreading, have led to a refinement in the application of plate tectonic theory to the evaluation of seismic potential.The term seismic gap is taken to refer to any region along an active plate boundary that has not experienced a large thrust or strike-slip earthquake for more than 30 years. A region of high seismic potential is a seismic gap that, for historic or tectonic reasons, is considered likely to produce a large shock during the next few decades. The seismic gap technique provides estimates of the location, size of future events and origin time to within a few tens of years at best.The accompanying map summarizes six categories of seismic potential for major plate boundaries in and around the margins of the Pacific Ocean and the Caribbean, South Sandwich and Sunda (Indonesia) regions for the next few decades. These categories range from what we consider high to low potential for being the site of large earthquakes during that period of time. Categories 1, 2 and 6 define a time-dependent potential based on the amount of time elapsed since the last large earthquake. The remaining categories, 3, 4, and 5, are used for areas that have ambiguous histories for large earthquakes; their seismic potential is inferred from various tectonic criteria. These six categories are meant to be interpreted as forecasts of the location and size of future large shocks and should not be considered to be predictions in which a precise estimate of the time of occurrence is specified.Several of the segments of major plate boundaries that are assigned the highest potential, i.e., category I, are located along continental margins, adjacent to centers of population. Some of them are hundreds of kilometers long. High priority should be given to instrumenting and studying several of these major seismic gaps since many are now poorly instrumented. The categories of potent...

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“…More recently, the mechanisms of intraplate earthquakes have been studied to determine the stress states in the plates, which bear directly on the driving mechanism of plate motions [Mendiguren, 1971;Forsyth, 1973 A compilation of the published results of the few available source mechanism solutions is shown in Figure 2. In the Chilean and Peruvian arcs, the mechanisms of upper plate shallow earthquakes obtained by Stauder [1973Stauder [ , 1975 log W0 = 1.5Mw + 11.8 Table 2 (from Table 2 …”

mentioning

confidence: 99%

Back‐arc opening and the mode of subduction

Uyeda¹,

Kanamori²

1979

J. Geophys. Res.

1,183

549

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Trench-arc systems (subduction zones) can be classified into two types depending on whether or not actively opening back-arc basins are associated with them. This suggests that subduction of an oceanic plate is not a sufficient condition for back-arc opening, though it may be necessary one. Mechanisms that cause the distinction between the two types have been investigated. Earthquake studies suggest that there is a significant difference in the mode of plate motion at interplate boundaries between the two types of

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Mechanism and spatial distribution of Chilean earthquakes with relation to subduction of the oceanic plate

Cited by 226 publications

References 20 publications

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

Slope instabilities at an active continental margin: large-scale polyphase submarine slides along the northern Peruvian margin, between 5 °S and 6 °S

Seismic Gaps and Plate Tectonics: Seismic Potential for Major Boundaries

Back‐arc opening and the mode of subduction

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