Determination of earthquake prone zones at university of tadulako based on dominant periods and peak ground acceleration (PGA)

University of Tadulako is the largest State University in Palu City. When an earthquake with a magnitude of 7.4 Mw on September 28, 2018, occurred, many buildings were damaged and even collapsed at that time, even causing casualties due to the rubble. Research on the Local Site Effect is essential for the assessment of seismic hazard. In this study, the local site effect was analyzed using the HVSR method based on microtremor data. The predominant Period (To) ranges between 1.709 s to 3.816 s, indicates that this area consists of alluvium and has a very thick sediment layer. Another parameter calculated in this paper is the peak ground acceleration (PGA) with values from 0.914 g to 0.924 g. This value is the first indicated soil damage level due to ground motions. The results of this study can be used as a consideration in the development of regional spatial planning and building structures based on earthquake analysis.

Reinforced masonry practical booklet

The main work explains the elaboration process of a didactic booklet that details the constructive method of reinforced masonry, final product of an investigation developed by the department of Architecture and Urbanism at Universidade Federal de Pernambuco (UFPE), entitled “Alvenaria Cerâmica Armada: uma cartilha prática”[1], at 2020. This article presents a discussion concerning urban sustainability, here understood not from it ecological dimension only, but also from it’s social and cultural. The post-modern Productivism from the 70’s decades impulses an architectural production which impacts the landscape and life quality of city’s population, presenting a homogenization in what concerns architecture. Contrasting this universalized architectural movement, some notably Latin-American architectural offices, using materials and local techniques, started to answer the local demands (and international) under the sustainable directive, intending to use low cost and using resources and rejects from local site to build. Based on the practical experience at one of these offices, the Paraguayan office Gabinete de Arquitectura, it was possible to elaborate a guidebook synthesizing some precepts and building techniques in reinforced masonry, a method easily reached by the most popular layers of society. By this guidebook it is uncovered many possibilities for an architectural low cost production with both social and cultural commitments. [1] Reinforced Masonry Practical Booklet.

Experimental Approach on the Study of Ground-Motion Amplification at the Cerro Prieto Volcano, Mexicali Valley, Baja California, Mexico

We conducted experimental work to explain the large peak ground accelerations observed at the Cerro Prieto volcano in Mexicali Valley, Mexico. Using ambient noise and earthquake data, we compared horizontal-to-vertical spectral ratios (HVSRs) computed for sites on the volcano against those calculated for locations outside it. High-HVSR values (∼11 at ∼2 Hz) were obtained on the top of the volcano at 183 m of altitude, decreasing for sites located at lower elevations. We calculated a median HVSR of ∼1 at 2 Hz from HVSRs computed for nine sites located along an N18°E transect and at an average elevation of ∼25 m. The earlier comparison suggests a relative amplification on the volcano. In addition, we calculated HVSRs from accelerograms generated by 62 earthquakes (2.6≤ML≤5.4; 4.6≤Mw≤7.2) recorded at four locations: two on the volcano (at 194 and 110 m of elevation) and two outside it. These last two sites, located up to 6 km away in a north-northwest and south-southwest direction relative to the volcano, are at an average altitude of 22 m. For the four locations, we also computed the HVSRs from ambient noise data. Although the HVSR results derived from both types of data are slightly different, we also found high HVSRs for the two sites on the volcano and low HVSRs for the two sites outside it, corroborating the relative amplification on the volcano. Using the 1D wave propagation modeling, based on the stiffness matrix method, we modeled the experimental HVSRs to analyze the local site effects. Therefore, we propose that the ground-motion amplification at the Cerro Prieto volcano may be due to a combination of its topography and shallow site effects.

A Novel Method for Predicting Local Site Amplification Factors Using 1-D Convolutional Neural Networks

The analysis of site seismic amplification characteristics is one of the important tasks of seismic safety evaluation. Owing to the high computational cost and complex implementation of numerical simulations, significant differences exist in the prediction of seismic ground motion amplification in engineering problems. In this paper, a novel prediction method for the amplification characteristics of local sites was proposed, using a state-of-the-art convolutional neural network (CNN) combined with real-time seismic signals. The amplification factors were computed by the standard spectral ratio method according to the observed records of seven stations in the Lower Hutt Valley, New Zealand. Based on the geological exploration data from the seven stations and the geological hazard information of the Lower Hutt Valley, eight parameters related to the seismic information were presumed to influence the amplification characteristics of the local site. The CNN method was used to establish the relationship between the amplification factors of local sites and the eight parameters, and the training samples and testing samples were generated through the observed and geological data other than the estimated values. To analyze the CNN prediction ability for amplification factors on unrecorded domains, two CNN models were established for comparison. One CNN model used about 80% of the data from 44 seismic events of the seven stations for training and the remaining data for testing. The other CNN model used the data of six stations to train and the remaining station’s data to test the CNN. The results showed that the CNN method based on the observation data can provide a powerful tool for predicting the amplification factors of local sites both for recorded positions and for unrecorded positions, while the traditional standard spectral ratio method only predicts the amplification factors for recorded positions. The comparison of the two CNN models showed that both can effectively predict the amplification factors of local ground motion without records, and the accuracy and stability of predictions can meet the requirements. With increasing seismic records, the CNN method becomes practical and effective for prediction purposes in earthquake engineering.