ESTIMATION OF SEISMIC INTENSITY FOR A SHAKE MAP DEVELOPMENT IN LIMA, PERU

Calderon D.; Calderon C.; Gonzales C. · World Conference on Earthquake Engineering proceedings (2021)

Resumen

It is well known that Peru is over a seismic activity area, called the “Pacific Ring of Fire”, an area where most of the earthquakes takes place. Attempts to estimate the seismic hazard of Lima city, the capital of Peru, have been developed through seismic microzoning studies, which have divided the city in five zones according to the mechanical characteristics of the soil deposits [1]. Although microzoning studies give us an important tool for adopting prevention measures, their results are qualitative, and if we want to quantify the real ground motion parameters distribution in an area during an earthquake, a shake map is necessary. It will further help as a tool to quickly identify areas that could be in potential damage due to a seismic event. In Japan a shake map has been developed following a methodology that correlates various parameters, such as, geology, soil type among others. The U.S. and Japan have developed shake maps through PAGER and QuiQuake system respectively, which started to operate since 2007 and 2009 respectively. A comparison of both systems (PAGER and QuiQuake) applied in Japan with observed data during past earthquakes was carried out [2]. The results shown that PAGER failed to estimate damage at high intensity regions while QuiQuake shown more precise results; this difference was attributed to the fact that PAGER uses empirical attenuation formulas in the calculation of intensities while QuiQuadke makes its calculation interpolating observed data and taking into account geomorphology conditions. In Peru, IGP (the Peruvian Geophysical Institute) manage a seismic network, and it is the official institution to provide information about epicenter, magnitude and other data related to earthquake occurrence. There are other institutions that manage seismic network as well, such as CISMID (Earthquake Research and Disaster Mitigation Center that belongs to the National University of Engineering), and CIP (the Peruvian Society of Civil Engineers). None of these institutions include shake maps in their reports, but CISMID and CIP are initiating what could be the first steps toward a creation of a shake map, interpolating values of peak acceleration recorded in their seismic stations, yet there is a large path to follow to create a shake map. Since the Japanese methodology have proved to be more precise, this methodology will be adopted to develop a shake map in Lima city. According to this methodology, in order to develop a shake map it is fundamental to calculate seismic intensity at the surface of each seismic station. This study focus in the estimation of this parameter based on recorded data of peak acceleration, geomorphological data, and other parameters; and the correlation among them are examined. Data from CISMID seismic network, which has the largest number of accelerometers installed in Lima city; as well as, data from microzoning studies, are used in this study. © The 17th World Conference on Earthquake Engineering.

Instituciones: Universidad Nacional de Ingeniería