Abstract. The source process of the October 9, 1995, ColimaJalisco, Mexico, earthquake (Mw=8.0), and its largest foreshock and aftershock were determined from teleseismic body waves, using a least-squares inversion scheme. The three events are shallow-dipping, thrust-fault earthquakes, in agreement with the relative plate motions for Rivera-North America and CocosNorth America plate boundaries. Neither the foreshock nor the largest aftershock show significant differences in focal mechanism nor centroidal depth with respect to the average mechanism of the mainshock. The rupture of the mainshock began near the foreshock hypocenter and propagated, with a variable rupture velocity, towards the NW. The source-time function for this event shows four distinct episodes of energy release. About 50% of the moment was released at the northern end of the rupture, between 90 and 110 km from the epicenter. This rupture geometry is in agreement with crustal deformation observed inland using GPS measurements. However, the scalar seismic moment of the main shock obtained in this study Subruction zones with slow convergence rates, similar to the Rivera margin, exhibit long periods of interseismic activity between large earthquakes [Heaton and Hartzell, 1986]. This does not appear to be the case along the Jalisco-Colima margin. On October 9, 1995, a great earthquake hit the coastal towns of Colima and Jalisco, causing severe damage from both the shaking and the tsunami that followed the earthquake [Borrero et al., 1997]. The damage during this earthquake, unlike the 1932 earthquakes, was limited to the coast. This fact, in addition to the large discrepancy observed between the reported magnitudes (Ms=7.4 by PDE and Mw=8.0 by Harvard CMT), calls for a detailed source study of this event. Here we present a teleseismic body-wave analysis of the mainshock, the foreshock, and the largest aftershock.

Dams' safety is highly important for authorities around the world. The impacts of a dam failure can be enormous. Models for investigating dam safety are required for helping decision-makers to mitigate the possible adverse consequences of flooding. A model for earth dam safety must specify clearly possible contributing factors, failure modes and potential consequences of dam failure. Probabilistic relations between variables should also be specified. Bayesian networks (BNs) have been identified as tools that would assist dam engineers on assessing risks. BNs are graphical models that facilitate the construction of a joint probability distribution. Most of the time, the variables included in a model for earth dam risk assessment involve continuous quantities. The presence of continuous random variables makes the implementation of discrete BNs difficult. An alternative to discrete BNs is the use of non-parametric continuous BNs, which will be briefly described in this article. As an example, a model for earth dams' safety in the State of Mexico will be discussed. Results regarding the quantification of conditional rank correlations through ratios of unconditional rank correlations have not been presented before and are introduced herein. While the complete application of the model for the State of Mexico is presented in an accompanying paper, here some results regarding model use are shown for demonstration purposes. The methods presented in this article can be applied for investigating risks of failure of civil infrastructures other than earth dams.

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Abstract. The 11 December, 1995 earthquake is the largest and best constrained instrumentally recorded event which has occurred on the Rivera-Cocos plate boundary. The reported focal mechanism for this event indicates almost pure strike-slip faulting with nodal planes oriented north-south and east-west. A visual inspection shows that the seismograms recorded worldwide strongly suggest a directivity effect indicative of a rupture propagating eastward from the epicenter. This observation is confirmed by a directivity analysis which shows a sharp reduction in the difference between observed and synthetic seismograms when the rupture direction is at an azimuth of approximately 90 ø . These results indicate that the east-west trending nodal plane of the earthquake of 11 December, 1995 is the actual fault plane. Considering that this is the largest instrumentally recorded earthquake in the region, it strongly suggests that the relative motion of the Rivera plate with respect to the Cocos plate takes place along east-west oriented faults, and that the sense of motion is right-lateral, strike-slip.

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