GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 However, the portions of the Balsamo range where the landslides actually occurred, show higher permanent displacement values, from 50 to 100 cm, especially in Fig. 3b (blue square). The spatial distribution of these values is due to the high-resolution DTM used, with 5x5 m cell size, that is able to capture the slope variations and their influence on the permanent displacements spatial distribution. Results from this study, although focussed on a limited area, can be seen as a test site for Jibson’s and Bray and Travasarou’s equations to predict where seismically induced landslides are likely to occur in the whole El Salvador volcanic territory. From the comparison between the landslide inventory on the Balsamo Range triggered by the 13 January earthquake and the calculated permanent displacements, Bray and Travasarou’s equation seems to be more reliable. Conclusions In this study we applied Jibson’s and Bray and Travasarou’s equations to predict co-seismic permanent displacements triggered by the 13 January 2001 strong earthquake in MASS. Both equations, for these volcanic deposits, show high D values where landslides occurred although Bray and Travasarou’s equation calculates high permanent displacements at larger areas. The DTM with cells 5x5 m is definitively useful in El Salvador territory where due to the geomorphological variations, such as the Balsamo range at San Salvador municipality, a finer description of the geomorphological features can effectively help to predict seismically induced small landslides. The D values could be used to identify landslides potentially triggered by other seismic events in the past. Finally, further tests of the previous equations in volcanic territories within El Salvador country are needed to state that Bray and Travasarou’s equation is more reliable than Jibson’s one. References Bommer J.J., and Rodrıiguez C.E.; 2002: Earthquake-induced landslides in Central America . Eng. Geol., 63 , 189– 220. Bray J. D., and Travasarou T.; 2007: Simplified procedure for estimating earthquake-induced deviatoric slope displacements. J. Geotech. Geoenviron. Eng., 133 (4), 381–392. Canora C., José, Martínez-Díaz J., Villamor P., Berryman K., Álvarez-Gómez J.A., Pullinger C., Capote R.; 2010: Geological and Seismological Analysis of the 13 February 2001 Mw 6.6 El Salvador Earthquake: Evidence for Surface Rupture and Implications for Seismic Hazard . Bull. Seismol. Soc. Am., 100 , 2873–2890. DOI: 10.1785/0120090377. Conrad P., and Bommer J.; 2001: Preliminary Observations on the El Salvador Earthquakes of January 13 and February 13, 2001 . EERI Special Earthquake Report, 1-12. Dewey J.W., and Suarez G.; 1991: Seismotectonics of Middle America . In: Slemmons, et al. (Ed.), Neotectonics of North America, Geological Society of America, Decade Map vol. 1 , 309– 321.