Looking inside the Continents from Space: Insights into Earthquake Hazard and Crustal Deformation

从太空看大陆内部：深入了解地震危害和地壳变形

• 批准号: NE/K010913/1
• 负责人: Juliet Biggs
• 金额: $ 14.67万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK010913%2F1
• 关键词: Looking; inside; Continents; Space; Insights

As two tectonic plates move together or apart, any continent trapped between them deforms, causing major geological features such as mountain belts or sedimentary basins to develop. As the brittle, near-surface crust tries to accommodate the deformation, earthquakes occur on faults inside the earth. The need to understand how the continents deform, and where earthquakes will occur, is compelling - between 1.4 and 1.7 million people have died in earthquakes in the continental interiors since 1900.We can measure the way the continents are actively deforming using satellites. GPS can provide very precise measurements of how individual points on the ground move, but such points are often sparsely distributed. Over the past two decades, satellites designed by the European Space Agency (ESA) have demonstrated the ability of satellite-borne radar to measure displacements of the earth's surface. The radar repeatedly sends out bursts of a microwave signal that scatters back from the surface and is measured when it returns to the spacecraft. We use differences in the radar returns acquired by the satellite at two different times to measure the displacement of that point over the intervening time interval. Displacements of a few millimeters or less can be measured in this way.As the continental crust deforms, the rocks continue to bend, building up strain that will be released in future earthquakes. When assessing earthquake hazard, in addition to knowing where the faults are on which the earthquakes will occur, it is essential to know the rate at which this strain is growing. These rates are small, however, and not easy to measure using radar in the presence of noise caused by changes on the ground from which the radar scatters and in the properties of the atmosphere through which the radar signal passes. In addition, errors in our knowledge of the position of the satellites affect our measurements. Methods can be devised to counter these difficulties, but the opportunities to apply them has been limited with the current satellites by the irregular and infrequent acquisition of radar images over many parts of the seismic belts.We are motivated to bring the efforts of a team of investigators to bear on these questions because of the planned launch by ESA in mid-to-late 2013 of Sentinel-1A, a new radar satellite. An identical partner, Sentinel-1B will be launched 18 months later. Each spacecraft will pass over a given point on the earth's surface every 6 days; once both are in orbit any point will be revisited every 3 days. This short time interval, plus the fact that observations will be made for every pass of the spacecraft and its position will be carefully controlled and well known, will mean a radical improvement in our ability to measure rates of motion and strain. By combining the measurements from all available satellite tracks, together with any GPS data available, we will be able to map in detail over large areas the rates at which strain is building up. We plan to look at what happens inside the continents as they deform by using such observations to test and constrain physical models. Thus the displacements occurring in an earthquake measured by radar can be used to infer the movements that have taken place on the fault at depth. The way the earth's surface in the vicinity of an earthquake continues to move immediately after it tells us about the mechanical properties of the surrounding region, knowledge essential to understanding how the forces around a fault vary with time. On a larger scale, the spatial distribution of strain in the continents tells us about changes in the strength of the crust. With these constraints we can test competing hypotheses about how the continents deform and what are the major factors controlling where the deformation occurs.

当两个构造板一起移动或分开时，它们之间的任何大陆变形，导致主要地质特征，例如山带或沉积盆地。随着脆性，近表面的地壳试图适应变形，地震发生在地球内部的断层上。自1900年以来，在大陆内部的地震中，在1.4到170万人之间，大陆的变形以及地震发生的地方如何变形以及地震的发生。我们可以衡量大陆使用卫星主动变形的方式。全科医生可以提供非常精确的测量值，以了解地面上各个点的移动方式，但是这种点通常分布得很稀少。在过去的二十年中，由欧洲航天局（ESA）设计的卫星证明了卫星传播雷达测量地球表面位移的能力。雷达反复发出微波信号的突发，该信号从表面散射，并在返回航天器时进行测量。我们使用卫星在两个不同时间获得的雷达回报中的差异，以测量间隔间隔中该点的位移。可以以这种方式测量几毫米或更少的位移。当大陆地壳变形时，岩石继续弯曲，建立将在未来地震中释放的应变。在评估地震危害时，除了知道地震发生的故障外，还必须知道这种菌株的增长速度。但是，这些速率很小，并且在存在雷达散射和雷达信号通过的大气特性的地面变化引起的噪声中，使用雷达很容易测量。此外，我们对卫星位置的了解会影响我们的测量。可以设计方法来应对这些困难，但是通过当前的卫星限制了应用它们的机会，这是由于在地震腰带的许多部分上不规则和不经常收购雷达图像的限制。我们有动力使调查人员的努力付诸实践，因为ESA计划在ESA计划在2013年中期的Newelel-sentinel-1a seplare satellite satellient satellient satellient，这是一个新的雷达。一个相同的合作伙伴Sentinel-1b将在18个月后推出。每个航天器每6天将每6天都超过地球表面上的一个给定点；一旦两者都在轨道上，每3天都会重新审视任何点。这个短时间间隔，以及对航天器的每次通过及其位置将被仔细控制和众所周知的事实，这将意味着我们测量运动和应变速率的能力有根本改善。通过将所有可用卫星轨道的测量结果与所有可用的GPS数据结合在一起，我们将能够在大面积上详细绘制菌株构建的速率。我们计划通过使用此类观测值测试和约束物理模型来查看它们在大洲变形时发生的事情。因此，通过雷达测量的地震中发生的位移可用于推断在深度处发生在断层上的运动。地震附近地球表面在告诉我们周围区域的机械性能之后，地震附近的表面继续移动，这对于理解断层周围的力如何随时间变化至关重要。在更大范围内，大陆菌株的空间分布告诉我们地壳强度的变化。借助这些约束，我们可以测试关于大陆如何变形以及控制变形发生何处的主要因素的竞争假设。

项目成果

Large-scale demonstration of machine learning for the detection of volcanic deformation in Sentinel-1 satellite imagery.

• DOI: 10.1007/s00445-022-01608-x
• 发表时间: 2022
• 期刊: Bulletin of volcanology
• 影响因子: 3.5

Controls on Early-Rift Geometry: New Perspectives From the Bilila-Mtakataka Fault, Malawi

对早期裂谷几何形状的控制：马拉维比利拉-姆塔卡塔卡断层的新视角

• DOI: 10.1029/2018gl077343
• 发表时间: 2018
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Hodge M

A semi-automated algorithm to quantify scarp morphology (SPARTA): application to normal faults in southern Malawi

• DOI: 10.5194/se-10-27-2019
• 发表时间: 2019-01
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: M. Hodge;J. Biggs;Å. Fagereng;A. Elliott;H. Mdala;F. Mphepo

Evidence From High-Resolution Topography for Multiple Earthquakes on High Slip-to-Length Fault Scarps: The Bilila-Mtakataka Fault, Malawi

• DOI: 10.1029/2019tc005933
• 发表时间: 2020-02-01
• 期刊: TECTONICS
• 影响因子: 4.2
• 作者: Hodge, M.;Biggs, J.;Williams, J. N.
• 通讯作者: Williams, J. N.

The Application of Convolutional Neural Networks to Detect Slow, Sustained Deformation in InSAR Time Series

• DOI: 10.1029/2019gl084993
• 发表时间: 2019-11-07
• 期刊: GEOPHYSICAL RESEARCH LETTERS
• 影响因子: 5.2
• 作者: Anantrasirichai, N.;Biggs, J.;Bull, D.
• 通讯作者: Bull, D.