Crustal stress across spatial scales

The study of crustal stress examines the causes and consequences of in-situ stress in the Earth’s crust. Stress at any given point has several geological sources, including ‘short-term and local-scale’ and ‘long-term, ongoing and wide-scale’ source. In order to better characterise the crustal stress state, the analyses of both local- and wide-scale sources, and the consequences of their superposition are required. The global compilation of stress data in the World Stress Map database has increased significantly since its first release in 1992 and its analysis revealed large rotations of the stress tensor in several intraplate settings.

Large-scale stress analysis, so called first-order, (> 500 km) provides information on the key drivers of the stress state that result from large density contrasts and plate boundary forces. The analyses of stress at smaller-scales (< 500 km) have numerous applications in reservoir geomechanics, geo-storage sites, civil engineering and mining industry. To date, numerous studies have investigated the stress analysis from different perspectives. However, the stress, in geosciences, is still enigmatic because it is a scale-dependant parameter. It means, stress variations can be studied at both the ‘spatial-scale’ and ‘temporal-scale’. This paper aims to investigate the crustal stress pattern with a particular emphasis on the orientation of maximum horizontal stresses at various spatial-scales, ranging from continental scales down to basin, field and wellbore scales, to better evaluate the role of various stress sources and their applications in the Earth’s crust. The stress analyses conducted in this work shows that stress pattern at large-scales do not necessarily represent the in-situ stress pattern at smaller-scales. Similarly, analysis of just a couple of borehole measurements in one area might not yield a good representation of the regional stress pattern.