The Influence of Earthquake Magnitude on Hazard Related to Induced Seismicity

Abstract

An increased focus on seismic hazard related to induced seismicity means that state-of-the-art approaches for earthquake monitoring and hazard estimation associated to tectonic earthquakes are now being applied at smaller and smaller scales. This chapter focuses on a specific issue related to this shift of focus to relatively small earthquakes in close proximity to urban areas. In tectonic earthquake hazard analyses we typically rely on a simple power-law scaling relating earthquake magnitude and recurrence. It is known, however, that for smaller earthquakes, the scaling between different magnitude types is not necessarily linear -meaning that a power law cannot be maintained over all magnitude types. Extrapolation to estimate the recurrence of earthquakes not yet recorded at the study site is therefore non-trivial. For earthquake hazard, the moment magnitude is typically used as input as it is easy to relate to ground motion through empirical equations or simulation approaches. However, for earthquake monitoring, maintaining a complete catalogue including moment magnitude of small events is technically difficult. Instead, a point-measure based magnitude, such as the local magnitude is usually determined. In the following the impact of the non-linear scaling between the magnitude of choice for local monitoring -the local magnitude -and that used for hazard analysis -the moment magnitude -is explored.

Bilinearity in the Gutenberg‐Richter Relation Based on ML for Magnitudes Above and Below 2, From Systematic Magnitude Assessments in Parkfield (California)

“…Our findings confirm the theoretical considerations of M L scaling breaks by Edwards () and Deichmann (). In principle, our study resolves the scaling‐related issues that have plagued many hazard and statistical seismology‐related studies in the past decade.…”

Underestimation of Microearthquake Size by the Magnitude Scale of the Japan Meteorological Agency: Influence on Earthquake Statistics

“…We discuss the potential contradiction among the M j -M w conversion (equation (6)) and the GR laws for M j and M w . As Edwards (2015) pointed out, since the slope of the M j -M w conversion is different in low and high magnitude ranges, this conversion bends the straight line of the magnitude-frequency distribution in a log linear plot. Therefore, if the GR law for M j worked perfectly, the GR law for M w could not be held.…”

Fast MW estimation of microearthquakes recorded around the underground gas storage in the Montello-Collalto area (Southeastern Alps, Italy)

“…At the same time, M W is preferred to M L in the probabilistic seismic hazard assessments, both for natural and induced earthquakes. Indeed, unlike M L , M W is not affected by saturation, anelastic attenuation, or scattering problems, and therefore, the fault to rupture provides more reliable estimations of the Gutenberg-Richter parameters (a and b values) (Edwards 2015;Staudenmaier et al 2018).…”