Based on Historical Seismic Damage Data to Rapidly Assessment the Vulnerability of Structures in Rural Village

This study investigated and classified typical structures in rural village and analyzed the vulnerability of various typical types of structures. Based on the statistics of earthquake damages with magnitudes above 5 from 1996 to 2013 in China, the damage matrixes of different types of structures in rural village are obtained. And The vulnerability index and the vulnerability equation of structure are crucial to assess the earthquake losses of typical structures under different magnitudes earthquakes. According to the seismic loss of different types of structures under different earthquake magnitudes, there are possible to improve the seismic resilience of the buildings in rural village. Moreover, the regional vulnerability is analyzed by β probability distribution function, and the comprehensive seismic performance index of different types of agricultural buildings in the region is obtained. The main research is to predict the loss of different types of structures under different earthquake magnitudes in the future, and to provide technical support for different types of building in rural village reinforcement.

Deep learning for earthquake detection and location

Understanding the causality between the events leading to fault slip and the earthquake recording is important for seismic design and monitoring of underground structures, bridges and reinforced concrete buildings as well as climate mitigation projects like carbon sequestration and energy technologies like enhanced geothermal systems or oilfield wastewater disposal. The Federal Emergency Management Agency (FEMA) reported in 2017, that earthquake losses in the United States add up to about \$6.1 billion dollars annually. This number only addresses direct economic losses to buildings, and does not cover damage and losses to critical facilities, transportation and utility lifelines or indirect economic losses. A holistic framework to study earthquakes would incorporate seismic wave propagation and pressure perturbations, and have a dialogue with the deep learning framework for earthquake detection and location. In this document, we delve into the deep learning module.

Impacts on catastrophe risk assessments from multi-segment and multi-fault ruptures in the UCERF3 model

The Uniform California Earthquake Rupture Forecast Version 3 (UCERF3) relaxes fault segmentation, allowing multi-segment and multi-fault ruptures through fault-to-fault “jumps,” with lengths up to ∼1200 km along the San Andreas Fault. Local faults are also highly interconnected, including ruptures on the order of hundreds of kilometers. These prescribed long ruptures did not exist in older models. Longer ruptures produce larger aggregate loss estimates for geographically dispersed assets (portfolios) due to the wider areas that are affected by strong ground shaking. In this study, we model probabilistic earthquake losses of a hypothetical state-wide building portfolio in California. We develop risk deaggregation methods to identify multi-segment and multi-fault ruptures that contribute significantly to high portfolio-wide risks. Three risk measures that are commonly used in risk management decisions are examined: Average Annual Loss (AAL), Return Period Loss (RPLα), and Tail Conditional Expectation (TCEα), for an annual exceedance probability “α,” or corresponding return period “1/α.” Our results show that while the super long ruptures (>500 km) contribute modestly (∼7%) to the portfolio AAL estimate, they contribute more significantly to portfolio catastrophe risk estimates. Specifically, at a 250 year return period, these long ruptures contribute about 26% and 32% to RPL250 and TCE250 estimates, respectively. At a 500-year return period, the corresponding contributions reach about 35% and 39%. Ruptures that connect complex fault systems are also found to be highly influential to estimated portfolio risks. At a 500-year return period, a mere six rupture groups contribute nearly 70% to the RPL500 estimate. Due to the importance of the UCERF3 model to many risk management and public policy decisions, a critical examination of the limit and uncertainty of fault connectivity and rupture lengths of future earthquakes, as well as their impacts on catastrophe risk assessments, is warranted in future model updates.

Using non-structural mitigation measures to maintain business continuity: a multi-stakeholder engagement strategy

Encouraging property owners and individuals to adopt mitigation measures to improve the resilience of their buildings and equipments to seismic hazard has been a major challenge in many earthquake- prone countries. Few business leaders are aware of the fragility of their supply chains or other critical systems due to earthquake hazard. Bridging the gap between research production and research use is another crucial challenge for the earthquake risk research process. The KnowRISK project outcome is aimed at encouraging the proactive engagement of multi- stakeholders (community at large, schools, business community and local govern-ment groups) undertaking non-structural mitigation measures that will minimize earthquake losses to individuals and communities. Engaging stakeholders, taking into account their needs and inputs to maintain critical and urgent business activities, can contribute to the research findings and ensure that our data collection is thorough and complete. Engagement with stakeholders, during the whole process can lead to improved outcomes and for the development of viable solutions, for business and society, because of stakeholder’s role and influence within the organizations.

SEISMIC ASSESSMENT OF CONTEMPORARY VERSUS OLD URBAN FRAME BUILDINGS

This comparative study probabilistically assesses the relative safety margins of code-compliant and pre-seismic code RC buildings with different heights in a region of medium seismicity. Detailed structural design and fiber-based modeling of six benchmark structures, namely two code-compliant buildings and two pre-code structures before and after retrofit, are undertaken to develop fragility functions using several earthquake records representing the most critical seismic scenario in the study area. Several inelastic dynamic analyses are performed to assess the seismic response and derive a range of fragility functions for the six benchmark buildings. Compared with contemporary structures, the study highlights the vulnerability of pre-code buildings due to the insufficient stiffness, strength, and ductility provided by their lateral force resisting systems. A practical retrofit solution for pre-code structures is subsequently assessed using the methodology adopted for other modern and old buildings. The probabilistic assessment results confirmed the comparable seismic performance of the retrofitted and code-conforming buildings. The comparative study, which provided insights into the differences between code-compliant versus pre-seismic code buildings before and after retrofit, contributes to reducing earthquake losses and improving community seismic resilience in earthquake-prone regions.

A new tool to simulate ground shaking and earthquake losses

The main purpose of SISMOTOOL suite is Planning and Management of Seismic Emergencies face to a future earthquake. This tool is written in ARCGIS software executing a fast and efficient determination of the estimated damage scenarios (pre-process) and a correlation with the observed damage results (post-process). First of all, the tool allows to select the earthquake source parameters through a defined database; moreover, several attenuation laws can be chosen and they can be combined according to the study area features. In addition, the local site effects are characterized from Vs30 values, which have been achieved by: i) topographic slope as a proxy obtained from Digital Elevation Model; ii) considering Vs30 values acquired from active and/or passive empirical methods; iii) a combination of both procedures through empirical local correlation laws. In the second place, the elements exposed to risk are incorporated by an automatic extraction from the cadastral database after inputs has been refined. Thirdly, vulnerability and estimated losses can be determined either empirically (EMS98 scale and Vulnerability Index, Iv) or analytically (Capacity spectrum). Additionally, a vulnerability modifier is implemented to account soil-structure resonance. Finally, SISMOTOOL quantifies the epistemic uncertainties in the input parameters using a logic tree. Last, but not least, SISMOTOOL results have been validated through a representative seismic scenario: the 1910 Adra earthquake (southern Spain) with moment magnitude (Mw) 6.3 and macroseismic intensity VIII (EMS98 scale) proves the reliability of SISMOTOOL program.

Exposure forecasting for seismic risk estimation: Application to Costa Rica

This study proposes a framework to forecast the spatial distribution of population and residential buildings for the assessment of future disaster risk. The approach accounts for the number, location, and characteristics of future assets considering sources of aleatory and epistemic uncertainty in several time-dependent variables. The value of the methodology is demonstrated at the urban scale using an earthquake scenario for the Great Metropolitan Area of Costa Rica. Hundreds of trajectories representing future urban growth were generated using geographically weighted regression and multiple-agent systems. These were converted into exposure models featuring the spatial correlation of urban expansion and the densification of the built environment. The forecasted earthquake losses indicate a mean increase in the absolute human and economic losses by 2030. However, the trajectory of relative risk is reducing, suggesting that the long-term enforcement of seismic regulations and urban planning are effectively lowering seismic risk in the case of Costa Rica.

An Analysis of Rural Households’ Earthquake-Resistant Construction Behavior: Evidence from Pingliang and Yuxi, China

Due to the lack of earthquake-resistant rural houses, small and medium earthquakes caused massive casualties in rural China. In 2004, China began implementing the Earthquake Rural Housing Safety Project Policy (ERHSPP) to reduce earthquake losses, mainly promoting the adoption of earthquake-resistant structures in rural residents’ self-built houses through subsidies, training of construction craftsmen, and provision of earthquake-resistant housing drawings. We conducted a field survey, collecting 1169 rural households in Pingliang, Gansu Province, and 1501 rural households in Yuxi, Yunnan Province, China. We studied Earthquake-Resistant Construction Behaviors (E-RCB) by the logistic and the ordered logistic regression models. Results show that government housing subsidy promotes E-RCB of rural households; E-RCB was affected by ERHSPP, positively correlated with economic status and housing earthquake damage; E-RCB was negatively correlated with structure danger, house age, and earthquake experience; and housing earthquake damage, not earthquake experience, strikingly promoted E-RCB in rural China. The results could provide suggestions in communication risk strategies for the government. We suggest the local government should promote local acceptable disaster propaganda, provide hierarchical housing subsidies, pay attention to housing seismic supervision, publish earthquake-resistant housing design drawings, and conduct more earthquake-resistant technical training for rural craftsmen.

Cost–benefit analyses to assess the potential of Operational Earthquake Forecasting prior to a mainshock in Europe

In the past couple of decades, Operational Earthquake Forecasting (OEF) has been proposed as a way of mitigating earthquake risk. In particular, it has the potential to reduce human losses (injuries and deaths) by triggering actions such as reinforcing earthquake drills and preventing access to vulnerable structures during a period of increased seismic hazard. Despite the dramatic increases in seismic hazard in the immediate period before a mainshock (of up to 1000 times has been observed), the probability of a potentially damaging earthquake occurring in the coming days or weeks remains small (generally less than 5%). Therefore, it is necessary to balance the definite cost of taking an action against the uncertain chance that it will mitigate earthquake losses. In this article, parametric cost–benefit analyses using a recent seismic hazard model for Europe and a wide range of inputs are conducted to assess when potential actions for short-term OEF are cost–beneficial prior to a severe mainshock. Ninety-six maps for various combinations of input parameters are presented. These maps show that low-cost actions (costing less than 1% of the mitigated losses) are cost–beneficial within the context of OEF for areas of moderate to high seismicity in the Mediterranean region. The actions triggered by OEF in northern areas of the continent are, however, unlikely to be cost–beneficial unless very large increases in seismicity are observed or very low-cost actions are possible.