The El Salvador earthquakes of January and February 2001: context, characteristics and implications for seismic risk

Bommer, Julian J.; Benito, M. B.; Ciudad-Real, M; Lemoine, Anne; López-Menjı́var, M.A; Madariaga, Raúl; Mankelow, J.M.; Hasbun, Patricia Méndez de; Murphy, William M.; Nieto-Lovo, M; Rodríguez-Pineda, Carlos Eduardo; Rosa, Herman

doi:10.1016/s0267-7261(02)00024-6

Cited by 56 publications

(30 citation statements)

References 39 publications

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“…Our preferred fault plane with strike, dip, and rake of 297°, 58°, −93° respectively, is consistent with the Harvard CMT or ERI determinations but our centroid depth is shallower, around 47 km. We find that little rupture occurred above 25 km depth, which is consistent with both the intraplate nature of this event and the very weak or even absent tsunami observed in the Pacific Ocean [ Bommer et al , 2002]. Rupture propagated mostly updip and toward the northwest resulting in a 50 km wide by 25 km along‐dip zone of high moment release (Figure 6).…”

Section: Discussionsupporting

confidence: 84%

“…The number of deaths might have been even greater if the event had occurred during the wet season when landslides are more easily triggered. A detailed report of this earthquake as well as the following shallow inland M = 6.6 earthquake (13 February 2001) is given by Bommer et al [2002]. Large intraplate earthquakes in subduction zones are quite common although very few have reached the magnitude of the January 2001 earthquake.…”

Section: Introductionmentioning

confidence: 99%

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The 13 January 2001 El Salvador earthquake: A multidata analysis

2003

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[1] On 13 January 2001, a large normal faulting intermediate depth event (M w = 7.7) occurred 40 km off the El Salvadorian coast (Central America). We analyze this earthquake using teleseismic, regional, and local data. We first build a kinematic source model by simultaneously inverting P and SH displacement waveforms and source time functions derived from surface waves using an empirical Green's function analysis. In an attempt to discriminate between the two nodal planes (30°trenchward dipping and 60°l andward dipping), we perform identical inversions using both possible fault planes. After relocating the hypocentral depth at 54 km, we retrieve the kinematic features of the rupture using a combination of the Neighborhood algorithm of Sambridge [1999] and the Simplex method allowing for variable rupture velocity and slip. We find updip rupture propagation yielding a centroid depth around 47 km for both assumed fault planes with a larger variance reduction obtained using the 60°landward dipping nodal plane. We test the two possible fault models using regional broadband data and near-field accelerograms provided by Universidad Centro Americana [2001]. Near-field data confirm that the steeper landward dipping nodal plane is preferred. Rupture propagated mostly updip and to the northwest, resulting in a main moment release zone of approximately 25 km Â 50 km with an average slip of $3.5 m. The large slip occurs near the interplate interface at a location where the slab steepens dip significantly. The occurrence of this event is wellexplained by bending of the subducting plate.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

The 13 January 2001 El Salvador earthquake: A multidata analysis

2003

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“…Most structures of this type did not sustain any damage, or suffered very slight damage, whilst adjacent adobe houses collapsed (Fig. 15d), a pattern of damage which had been previously observed following the 2001 El Salvador earthquake (Bommer et al 2002). The good performance of RC-confined masonry structures may be related to local construction practices, which ensure that brick walls and reinforced concrete elements have solid joints.…”

Section: Observations Of Structural Damage In the Light Of Local Consmentioning

confidence: 68%

“…The economic and social consequences for the affected region of the Pisco earthquake were nevertheless severe, and therefore further investigations into the nature of ground motions from subduction-zone earthquakes are justified. There are furthermore strong reasons to believe that the ground motions from crustal and subduction events are fundamentally different in nature, not least because of differences in the magnitude and distance ranges considered, but also as a result of differences in duration and the rate of energy release (e.g., Bommer et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Ground motions observed during the 15 August 2007 Pisco, Peru, earthquake

Tavera

Bernal

Strasser

et al. 2008

Bull Earthquake Eng

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A M w 7.9 earthquake event occurred on 15 August 2007 off the coast of central Peru, 60 km west of the city of Pisco. This event is associated with subduction processes at the interface of the Nazca and South American plates, and was characterised by a complex source mechanism involving rupture on two main asperities, with unilateral rupture propagation to the southeast. The rupture process is clearly reflected in the ground motions recorded during this event, which include two separate episodes of strong shaking. The event triggered 18 accelerographic stations; the recordings are examined in terms of their characteristics and compared to the predictions of ground-motion prediction equations for subduction environments, using the maximum-likelihood-based method of Scherbaum et al. (Bull Seismol Soc Am 94(6):2164-2185, 2004. Additionally, macroseismic observations and damage patterns are examined and discussed in the light of local construction practices, drawing on field observations gathered during the post-earthquake reconnaissance missions.

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“…We estimate their rupture parameters (slip and rupture size), based on the CMT catalogue and scaling laws (Wells & Coppersmith 1994). For 2001, M w = 7.7 earthquake in El Salvador in particular, these parameters are given by Bommer et al (2002) and Vallée et al (2003). We use an elastic half‐space model (Okada 1985) to estimate the cumulative coseismic displacements associated with the selected earthquakes at each GPS site (Tables S2 and S3), and take them into account during the GLOBK combination process.…”

Section: Data and Processingmentioning

confidence: 99%

Fault kinematics in northern Central America and coupling along the subduction interface of the Cocos Plate, from GPS data in Chiapas (Mexico), Guatemala and El Salvador

Franco¹,

Lasserre²,

Lyon‐Caen³

et al. 2012

Geophysical Journal International

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International audienceNew GPS measurements in Chiapas (Mexico), Guatemala and El Salvador are used to constrain the fault kinematics in the North America (NA), Caribbean (CA) and Cocos (CO) plates triple junction area. The regional GPS velocity field is first analysed in terms of strain partitioning across the major volcano-tectonic structures, using elastic half-space modelling, then inverted through a block model. We show the dominant role of the Motagua Fault with respect to the Polochic Fault in the accommodation of the present-day deformation associated with the NA and CA relative motion. The NA/CA motion decreases from 18-22 mm yr−1 in eastern Guatemala to 14-20 mm yr−1 in central Guatemala (assuming a uniform locking depth of 14-28 km), down to a few millimetres per year in western Guatemala. As a consequence, the western tip of the CA Plate deforms internally, with ≃9 mm yr−1 of east-west extension (≃5 mm yr−1 across the Guatemala city graben alone). Up to 15 mm yr−1 of dextral motion can be accommodated across the volcanic arc in El Salvador and southeastern Guatemala. The arc seems to mark the northern boundary of an independent forearc sliver (AR), pinned to the NA plate. The inversion of the velocity field shows that a four-block (NA, CA, CO and AR) model, that combines relative block rotations with elastic deformation at the block boundaries, can account for most of the GPS observations and constrain the overall kinematics of the active structures. This regional modelling also evidences lateral variations of coupling at the CO subduction interface, with a fairly high-coupling (≃0.6) offshore Chiapas and low-coupling (≃0.25) offshore Guatemala and El Salvador

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The El Salvador earthquakes of January and February 2001: context, characteristics and implications for seismic risk

Cited by 56 publications

References 39 publications

The 13 January 2001 El Salvador earthquake: A multidata analysis

The 13 January 2001 El Salvador earthquake: A multidata analysis

Ground motions observed during the 15 August 2007 Pisco, Peru, earthquake

Fault kinematics in northern Central America and coupling along the subduction interface of the Cocos Plate, from GPS data in Chiapas (Mexico), Guatemala and El Salvador

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