Forensic investigation of Gumbasa irrigation main canal damage due to large-scale flow liquefaction in Sibalaya caused by the 2018 Sulawesi Earthquake

This study conducted an extensive soil investigation in the Sibalaya liquefaction area to identify the Gumbasa main canal’s damage triggered by flow liquefaction. Several field tests and trenches with approximately 4 m were excavated to observe liquefied soil layers directly near the canal. A borehole, standard penetration test, and multichannel analysis surface waves (MASW) were performed beside the trench to obtain each layer’s penetration resistance. This research aims to understand the landslide’s whole aspect. The ground movements were analyzed by using satellite photos before and after the earthquake. The displacement of the main canal, the typical damage inventory, and the proposed reconstruction of the main canal are the focus of this study. As a result of the forensic investigation, the liquefied layers and debris flow contributing to the massive landslide were identified to impact the primary canal. The typical damage of the canal was due to surface rupture that occurred both horizontally and vertically. A solution for reconstructing the main canal is to use a flexible pipe canal structure. That will be resilient to future earthquake and ground movements, stabilize the ground downslope of the existing canal to limit the risk of future lateral movement in future earth tremors.

Evaluation of masonry buildings and mosques after Sivrice earthquake

The evaluation of masonry and mosque type structures after the Sivrice Earthquake is presented in this study. Stone masonry buildings exhibited damage such as vertical cracks and splitting at corners, wedge shaped corner failures, diagonal cracking on walls, out-of-plane splitting of walls, and separation of walls from flooring/roofing systems. On the other hand, the separation of flags and caps of minarets was a common example of damage in mosques. Future earthquake damage can be prevented by following design codes and providing adequate supervision for new structures, while strengthening measures are recommended for the existing buildings.

DEPREMLERİN COVİD-19 PANDEMİSİ ÜZERİNE ETKİLERİ

The pandemic (2019-202?) caused by the SARS-CoV-2 virus, which is the cause of the COVID-19 disease, has already taken its place in modern human history. In the first months of the pandemic, as a result of the sudden and intense interruption of human activities, the decrease in nature-human relationship has created noticeable effects on the environment. Most governments take measures to reduce the spread of infection, primarily by increasing the capacity of the health system and the social distance between people. An earthquake that may occur during a pandemic may interfere with the effective implementation of such measures and cause an increase in the spread of the virus. This study aims to analyze the potential effect of the infection rate that may increase after an earthquake in a region where the pandemic continues, and the effect of a future earthquake on the spread of the virus. An open-access software was used for this and data on locally verified case numbers were combined with a seismic hazard and risk map to create a combined index. This index reveals areas where integrated disaster preparedness and emergency plans should be developed to take into account the likelihood of the spread of the post-earthquake COVID-19 outbreak.

PERBANDINGAN KERUSAKAN AKTUAL DAN PRAKIRAAN PADA BANGUNAN TEMBOK TANPA PERKUATAN AKIBAT GEMPA

On April 18, 2018, an earthquake hit Banjarnegara Regency, Central Java. The earthquake was measured M4.4 at a depth of 4 km and caused damages to buildings in several villages within Kalibening District. Predicting the future earthquake events is difficult. However, it is possible to estimate the potential damage caused by an earthquake event. FEMA has developed a methodology called HAZUS to estimate the potential loss and damage caused by earthquakes. This study compared the level of actual damage to buildings subjected to the 2018 Banjarnegara earthquake with the estimated damage to buildings obtained using HAZUS. The real damage is obtained from the field survey while the estimated damage is obtained from the HAZUS modeling. The object of this research is the unreinforced masonry low-rise buildings (URML) in Kasinoman Village, one of the villages that suffered the most subjected to the 2018 Banjarnegara Earthquake. The result of this study indicates the actual damage has a higher mean damage ratio (20,40 %) compared to the estimated damage (11.66%). HAZUS is developed according to the performance and experimental data of the buildings in the US therefore it might not be compatible with the building in Indonesia, especially surveyed buildings in Banjarnegara. The reason is the buildings in the US fulfilled the earthquake-resistant building provision meanwhile the surveyed buildings did not.

Who Has Benefited? A Socio-Ecological Chronology of Urban Resilience in the Early Reconstruction of Talca after the 27-F Earthquake, Chile 2010–2012

This article engages in the understanding of resilience from the perspective of socio-ecological systems (SES) and the reconstitution of events of recovery and reconstruction in the city of Talca after the 27-F earthquake in Chile, between 2010 and 2012. For such purposes, we have developed a chronological or timeline-analysis model. This methodology, which uses mostly ethnographic and participant-observation techniques to recapitulate these events, observes the interaction of social agents, elements of the built environment, government institutions, and other institutional functions of the urban domain within the socio-ecological panarchy. The results suggest that key events, such as local government institutional actions, the observation of probable property speculation events, and community agency efforts dismissal, among other factors, could alter both human and natural resilience processes. In turn, this could affect the capacity of this city, its inhabitants, and its social institutions to endure future crises, as a product of deteriorated and maladaptive resilience mechanisms, aside from the natural and geographical conditions of Chile, exposed to future earthquake events. Likewise, the partial loss of the civic environment in this historic city and weakened neighborhood networks, contrasting with the redevelopment of real estate in central areas, altogether portray considerable risks with regard to the (un)generated social mechanisms of resilience, affecting future developments. The final section focuses on discussing these findings and their relevance in integrating a coherent understanding of SES resilience in urban planning and governance practice, especially in cities or urban areas that are prone to natural risks or catastrophes.

Обоснование основных положений деформационной модели подготовки очага корового землетрясения

The article reasonably shows that the uppermost layer of the Earth's crust up to 25 kilometers is seismogenic. Aim. The article provides the evidence that crustal seismicity is generated not by regional stress fields of a homogeneous shear, as it was adopted in the strategy for solving the problem of earthquake forecast, but by local fields of exponential elastic stress. Such fields arise in one or another section of a seismogenic fault due to the occurrence of a stress concentrator in this section. According to the Saint Venant principle, such a stress concentrator (an additional load in the system) generates a local stress field of an exponential form. In this field the maximum stress is localized in the areas of an increment load application (in the fault) and decreases very quickly (exponentially) on both sides of the fault. Such stress concentrators arise in those areas of a seismogenic fault, where displacements along the fault stop due to various reasons. G.A. Gamburtsev foresaw this situation and very precisely called such concentrators as “seams”. The origin of a local stress field at the place, where a seam appears, is caused by the following fact: the power impulse generated by the seam is small compared to the linear momentum of the entire system of blocks of the considered fault and, therefore, it will stop the displacement of blocks only within the seam; but the displacements of blocks outside the seam will continue in the same mode. One can single out the following reasons causing stress concentrators in the fault: variations in different stress fields, changing the value of the friction coefficient in the fault; variations in fluid processes; the influence of temperature and pressure; mechanical “hooks” of blocks due to irregularities of their contacting surfaces, etc. Methods. The fact of the existence of the considered local stress fields is confirmed by geodetic studies, i.e. the results of repeated geodetic measurements in the epicentral zones of strong earthquakes. Results.These results allow drawing the following conclusions: 1) the sign of the preparation of a crustal earthquake source was reliably determined. This sign means the increasing deformation of the elastic bending of rocks in the source in the course of time; 2) from the standpoint of solving the problem of earthquake forecast, the main and decisive result of these studies is that the deformation processes occurring in the impending source also capture the Earth's surface, because this is precisely what opens up great opportunities in solving this problem; 3) with the help of special geodetic systems (forecast profiles), one can detect the places of the impending earthquake source preparation, i.e. make an accurate forecast of the site of a future earthquake; 4) since the energy of the earthquake source is functionally related to its size, one can realize the correct prediction of the maximum possible intensity of the future earthquake by determining the length of the seismogenic fault section, elastically deformed by the preparation of the earthquake using the forecast profiles В статье обоснованно показано, что сейсмогенным является самый верхний слой земной коры мощностью до 25 километров. Цель работы. В статье приведены доказательства того, что коровая сейсмичность порождается вовсе не региональными полями напряжений однородного сдвига, как это было принято в стратегии решения проблемы прогноза землетрясений, а локальными полями упругих напряжений экспоненциального вида. Такие поля возникают в том или ином участке сейсмогенного разлома из-за появления на этом участке концентратора напряжений. Согласно принципу Сен-Венана такой концентратор напряжений (дополнительная нагрузка в системе) порождает локальное поле напряжений экспоненциального вида. Максимальная величина напряжения в этом поле расположена в месте приложения дополнительной нагрузки (в разломе) и очень быстро (экспоненциально) убывает в обе стороны от разлома. Такие концентраторы напряжений возникают на тех участках сейсмогенного разлома, на которых в силу тех или иных причин прекращаются смещения по разлому. Г.А. Гамбурцев провидчески предвидел данную ситуацию и очень метко такие концентраторы назвал «спайками»». Возникновение локального поля напряжений в месте появления спайки обусловлено тем, что импульс силы, порождаемый спайкой мал по сравнению с количеством движения всей системы блоков рассматриваемого разлома и, следовательно, он остановит смещение блоков лишь в пределах спайки, но смещения блоков вне спайки будут продолжаться в прежнем режиме. Среди причин, порождающих концентраторы напряжений в разломе можно назвать следующие: вариации различных полей напряжений, изменяющие величину коэффициента трения в разломе; влияние температуры и давления; вариации флюидных процессов; механические «зацепы» блоков из-за неровностей их соприкасающихся поверхностей и др. Методы исследования. Факт существования рассматриваемых локальных полей напряжений подтвержден геодезическими исследованиями – результатами повторных геодезических измерений в эпицентральных зонах сильных землетрясений. Результаты работы. Эти результаты позволяют сделать следующие выводы: 1) достоверно определен признак подготовки очага корового землетрясения, которым является нарастающая во времени деформация упругого изгиба горных пород в его очаге; 2) с позиций решения проблемы прогноза землетрясений главным и определяющим результатом этих исследований является то, что происходящие в готовящемся очаге деформационные процессы захватывают и земную поверхность, ибо именно это открывает большие возможности в решении этой проблемы; 3) с помощью специальных геодезических систем (прогнозных профилей) можно обнаруживать места подготовки очагов готовящихся землетрясений, т.е. осуществлять точный прогноз места будущего землетрясения; 4) так как энергия очага землетрясения функционально связана с его размерами, то определив с помощью прогнозных профилей длину участка сейсмогенного разлома, упруго деформированного подготовкой землетрясения, можно осуществить и точный прогноз максимально возможной силы будущего землетрясения

The challenges and possibilities of earthquake predictions using non-seismic precursors

The catastrophic magnitude of life and monetary losses associated with earthquakes deserve serious attention and mitigation measures. However, in addition to the pre-earthquake and post-earthquake alleviation actions, the scientific community indeed needs to reconsider the possibilities of earthquake predictions using non-seismic precursors. A significant number of studies in the recent decades have reported several possible earthquake precursors such as anomalies in electric field, magnetic field, gas/aerosol emissions, ionospheric signals, ground water level, land surface temperature, surface deformations, animal behaviour, thermal infrared signals, atmospheric gravity waves, and lightning. Such substantial number of scientific articles and reported anomalous signals cannot be overlooked without a thoughtful appraisal. Here, we provide an opinion on the way forward for earthquake prediction in terms of challenges and possibilities while using non-seismic precursors. A general point of concern is the widely varying arrival times and the amplitudes of the anomalies, putting a question mark on their universal applicability as earthquake markers. However, a unifying concept which does not only define the physical basis of either all or most of these anomalies but which also streamlines their characterisation procedure must be the focus of future earthquake precursory research. Advancements in developing the adaptable instrumentation for in-situ observations of the claimed non-seismic precursors must be the next step and the satellite observations should not be taken as a replacement for field-based research. We support the need to standardise the precursor detection techniques and to employ a global-scale monitoring system for making any possible earthquake predictions reliable.

Forecasting for a Fractured Land: A Case Study of the Communication and Use of Aftershock Forecasts from the 2016 Mw 7.8 Kaikōura Earthquake in Aotearoa New Zealand

Operational earthquake forecasts (OEFs) are represented as time-dependent probabilities of future earthquake hazard and risk. These probabilities can be presented in a variety of formats, including tables, maps, and text-based scenarios. In countries such as Aotearoa New Zealand, the U.S., and Japan, OEFs have been released by scientific organizations to agencies and the public, with the intent of providing information about future earthquake hazard and risk, so that people can use this information to inform their decisions and activities. Despite questions being raised about the utility of OEF for decision-making, past earthquake events have shown that agencies and the public have indeed made use of such forecasts. Responses have included making decisions about safe access into buildings, cordoning, demolition safety, timing of infrastructure repair and rebuild, insurance, postearthquake building standards, postevent land-use planning, and public communication about aftershocks. To add to this body of knowledge, we undertook a survey to investigate how agencies and GNS Science staff used OEFs that were communicated following the Mw 7.8 2016 Kaikōura earthquake in Aotearoa New Zealand. We found that agencies utilized OEFs in many of the ways listed previously, and we document individual employee’s actions taken in their home-life context. Challenges remain, however, regarding the interpretation of probabilistic information and applying this to practical decision-making. We suggest that science agencies cannot expect nontechnical users to understand and utilize forecasts without additional support. This might include developing a diversity of audience-relevant OEF information for communication purposes, alongside advice on how such information could be utilized.