Quake4D - building physics-based, geologically-rich models for investigating earthquake interaction and seismic hazard

地震是对广大人口构成的最大自然威胁之一。在上个世纪，地震造成230万人死亡(仅过去30年就有100万人死亡)和8200亿美元的经济损失。地震是沿着被称为“活动断层”的地质软弱带运动而产生的，在某些地方，可以在地球表面观察到这种断层。与其他自然灾害不同，科学认识的进步尚未导致地震死亡人数的减少。预测个别地震的时间、地点和震级可能是不可能的，但估计地震风险的空间分布是可控的，对全球人口和保险经济非常重要。然而，由于我们目前依赖目前对断层移动速度的测量和过去破坏性地震的历史记录，因此计算地震危险是困难的。我们不能简单地对地震进行更长时间的观测，因此我们必须开发更丰富的地质学数值模拟，以建立综合地震记录和地震风险模型，以提高我们对控制地震的基本过程的理解。这个项目将开发一种新的、地质学丰富的、完全集成的、基于物理的方法来模拟地震周期的所有方面。地震周期是地震发生的周期性，随着时间的推移，构造应力累积，然后在一系列地震中释放。控制地震周期的物理过程在不同的时间尺度上运行，从地震期间的几秒钟到同一断层上反复发生的地震之间的数千年。断层的形状和间距也影响着地震的发生方式，但要看到地球表面断层的真实形状并不总是那么容易。地震周期有三个阶段，目前是单独建模的。它们是：1.地震中发生的几秒到几分钟的断层滑动的动态过程；2.由此产生的形变和应力向周围断层的转移；3.地震间构造应力的演化和积累。这三个阶段中的每一个都可以单独建模，用于推测地震周期的不同方面。然而，由于它们目前还没有整合在一起，人们对每个因素对其他因素的影响知之甚少。将对几个活动和不活动的伸展断裂系统进行研究。将对地震活跃的意大利亚平宁中部和南部进行研究，因为那里有丰富的数据可用；断层在地表暴露得很好，有700年的破坏性地震记录，因此地震风险很高。将研究的非活动断层系统是挪威近海、澳大利亚和新西兰。研究这些不活跃的系统很重要，因为我们可以使用地震反射(如海底地面的回波定位)来成像断层，查看它们的3D形状，并研究它们是如何随时间演变的。这些断层的滑动速率可以通过研究这些断层的年龄和错距来量化。重要的是要研究一系列不同的系统，以综合这些地区可用的不同数据集。总而言之，地震风险预测目前落后于其他自然灾害的预测。通过结合三种不同的基于物理的建模方法，并在两个数据丰富的天然断层系统上测试所产生的模型，该项目将生成一个真正的断层系统的物理和地质模型--这是以前从未尝试过的。这些模型将输出合成地震目录，这些目录可以与历史记录进行比较(后向广播)，用于推测地震的未来位置(预测)，并用于通知和理解地震危险模式中的不确定性

Earthquakes pose one of the greatest natural threats to vast populations. In the last century, earthquakes have caused 2.3 million deaths (1 million in the last 30 years alone) and US$820 billion of financial losses. Earthquakes are generated by movement along lines of geological weakness called "active faults" which, in some places, can be observed on the Earth's surface. Unlike other natural hazards, advances in scientific understanding have not yet led to a reduction in fatalities from earthquakes. Predicting the timing, location and magnitude of individual earthquakes is likely impossible, but estimating the spatial distribution of earthquake hazard is manageable, and of great importance to the global population and the insurance economy. However, there are difficulties in calculating the earthquake hazard because we are currently reliant on present-day measurements of the rates of movement of faults and historical records of past damaging earthquakes. We cannot simply observe earthquakes for longer, therefore we must develop 'geologically richer' numerical simulations to build synthetic earthquake records and seismic hazard models to improve our understanding of the fundamental processes that control earthquakes.This project will develop a new, geologically-rich, fully integrated physics-based approach to modelling all aspects of the earthquake cycle. The earthquake cycle is the cyclical nature of earthquakes occurring, with tectonic stress building up and then releasing in a series of earthquakes over time. The physical processes that control the earthquake cycle operate on different time-scales, from seconds during the earthquake to millennia between earthquakes recurring on the same fault. The shape and spacing of faults also affect how earthquakes are generated, but it is not always easy to see the true shape of faults at the Earth's surface. There are three stages of the earthquake cycle that are currently modelled separately. These are; 1. the dynamic process of fault slip occurring over seconds to minutes during the earthquake, 2. the resulting deformation and stress transfer onto surrounding faults and 3. the evolution and accumulation of tectonic stress between earthquakes. Each of these three stages can be modelled individually and are used to speculate on different aspects of the earthquake cycle. However, because they are presently not integrated, the effects of each one on the others are poorly understood. Several active and inactive systems of extensional faults will be studied. The seismically active central and southern Italian Apennines will be studied because there is a wealth of data available; the faults are well-exposed at the surface and there is a 700 years record of damaging earthquakes and therefore high seismic hazard. The inactive fault systems that will be studied are offshore Norway, Australia and New Zealand. These inactive systems are important to study because we can use seismic reflection (like echo-location of the ground under the sea bed) to image the faults, to see their 3D shape and study how that has evolved with time. The slip rate on these faults can be quantified by studying the age and offset across these faults. It's important to study a range of different systems to synthesise the different data sets available in these regions. In summary, earthquake hazard forecasting is currently lagging behind forecasting of other natural hazards. By combining three different physics-based modelling approaches and testing the resulting model on two data-rich natural fault systems, this project will generate a truly physical and geological model of a fault system - this has not been attempted before. These models will output synthetic earthquake catalogues that can be compared to historical records (hindcasting), used to speculate on the future locations of earthquakes (forecasting) and used to inform and understand uncertainty in seismic hazard mode