Earthquake Fault Scaling: Self-Consistent Relating of Rupture Length, Width, Average Displacement, and Moment Release

Abstract. We present an analytical, seismologically consistent expression for the surface area of the region within which most landslides triggered by an earthquake are located (landslide distribution area). This expression is based on scaling laws relating seismic moment, source depth, and focal mechanism with ground shaking and fault rupture length and assumes a globally constant threshold of acceleration for onset of systematic mass wasting. The seismological assumptions are identical to those recently used to propose a seismologically consistent expression for the total volume and area of landslides triggered by an earthquake. To test the accuracy of the model we gathered geophysical information and estimates of the landslide distribution area for 83 earthquakes. To reduce uncertainties and inconsistencies in the estimation of the landslide distribution area, we propose an objective definition based on the shortest distance from the seismic wave emission line containing 95 % of the total landslide area. Without any empirical calibration the model explains 56 % of the variance in our dataset, and predicts 35 to 49 out of 83 cases within a factor of 2, depending on how we account for uncertainties on the seismic source depth. For most cases with comprehensive landslide inventories we show that our prediction compares well with the smallest region around the fault containing 95 % of the total landslide area. Aspects ignored by the model that could explain the residuals include local variations of the threshold of acceleration and processes modulating the surface ground shaking, such as the distribution of seismic energy release on the fault plane, the dynamic stress drop, and rupture directivity. Nevertheless, its simplicity and first-order accuracy suggest that the model can yield plausible and useful estimates of the landslide distribution area in near-real time, with earthquake parameters issued by standard detection routines.

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“…Following Marc et al (2016b), we use the scaling of fault rupture length, L, with seismic moment proposed by Leonard (2010):…”

Section: A Seismologically Consistent Expression For the Landslide DImentioning

confidence: 99%

Prediction of the area affected by earthquake-induced landsliding based on seismological parameters

Marc

Meunier

Hovius

2017

Nat. Hazards Earth Syst. Sci.

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“…Although fault width cannot be directly obtained via our method, we could assume it approximately scales with fault length following a well-established empirical relationship, w = 1.7L 2/3 , for 5.5 < L < 1500 km (Leonard 2010). Fault width is assumed equal to fault length if L < 5.5 km.…”

Section: Directivity Moment Tensor Inversion 1073mentioning

confidence: 99%

“…Also, it has long been recognized that strike-slip earthquakes become width-limited at widths of 12-20 km; for strike-slip events with w > 15 km, we fix the width to 15 km (i.e. the average seismogenic depth; Leonard 2010). Therefore, the fault width for the Nantou earthquake, the Kumamoto earthquake, and the SJFT earthquake are 10.3, 15 (width-limited), and 2.8 km (w = L), respectively.…”

Section: Directivity Moment Tensor Inversion 1073mentioning

confidence: 99%

Toward automated directivity estimates in earthquake moment tensor inversion

Huang

Aso

Tsai

2017

Geophysical Journal International

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S U M M A R YRapid estimates of earthquake rupture properties are useful for both scientific characterization of earthquakes and emergency response to earthquake hazards. Rupture directivity is a particularly important property to constrain since seismic waves radiated in the direction of rupture can be greatly amplified, and even moderate magnitude earthquakes can sometimes cause serious damage. Knowing the directivity of earthquakes is important for ground shaking prediction and hazard mitigation, and is also useful for discriminating which nodal plane corresponds to the actual fault plane particularly when the event lacks aftershocks or outcropped fault traces. Here, we propose a 3-D multiple-time-window directivity inversion method through direct waveform fitting, with source time functions stretched for each station according to a given directivity. By grid searching for the directivity vector in 3-D space, this method determines not only horizontal but vertical directivity components, provides uncertainty estimates, and has the potential to be automated in real time. Synthetic tests show that the method is stable with respect to noise, picking errors, and site amplification, and is less sensitive to station coverage than other methods. Horizontal directivity can be properly recovered with a minimum azimuthal station coverage of 180 • , whereas vertical directivity requires better coverage to resolve. We apply the new method to the M w 6.0 Nantou, Taiwan earthquake, M w 7.0 Kumamoto, Japan earthquake, and M w 4.7 San Jacinto fault trifurcation (SJFT) earthquake in southern California. For the Nantou earthquake, we corroborate previous findings that the earthquake occurred on a shallow east-dipping fault plane rather than a west-dipping one. For the Kumamoto and SJFT earthquakes, the directivity results show good agreement with previous studies and demonstrate that the method captures the general rupture characteristics of large earthquakes involving multiple fault ruptures and applies to earthquakes with magnitudes as small as M w 4.7.

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“…7, an earthquake fault relationship, after Leonard (2010), is shown modified for maximum observed magnitudes at geothermal sites (green stars) and tectonic earthquakes (red stars). Formulas used to prepare this figure and references are listed in Table 3.…”

Section: Maximum Observed and Expected Seismic Magnitudementioning

confidence: 99%

Analysis of induced seismicity in geothermal reservoirs – An overview

et al. 2014

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In this overview we report results of analysing induced seismicity in geothermal reservoirs in various tectonic settings within the framework of the European Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs (GEISER) project. In the reconnaissance phase of a field, the subsurface fault mapping, in situ stress and the seismic network are of primary interest in order to help assess the geothermal resource. The hypocentres of the observed seismic events (seismic cloud) are dependent on the design of the installed network, the used velocity model and the applied location technique. During the stimulation phase, the attention is turned to reservoir hydraulics (e.g., fluid pressure, injection volume) and its relation to larger magnitude seismic events, their source characteristics and occurrence in space and time. A change in isotropic components of the full waveform moment tensor is observed for events close to the injection well (tensile character) as compared to events further away from the injection well (shear character). Tensile events coincide with high Gutenberg-Richter -values and low Brune stress drop values. The stress regime in the reservoir controls the direction of the fracture growth at depth, as indicated by the extent of the seismic cloud detected. Stress magnitudes are important in multiple stimulation of wells, where little or no seismicity is observed until the previous maximum stress level is exceeded (Kaiser Effect). Prior to drilling, obtaining a 3D -wave ( ) and -wave velocity ( ) model down to reservoir depth is recommended. In the stimulation phase, we recommend to monitor and to locate seismicity with high precision (decametre) in real-time and to perform local 4D tomography for velocity ratio ( / ). During exploitation, one should use observed and model induced seismicity to forward estimate seismic hazard so that field operators are in a position to adjust well hydraulics (rate and volume of the fluid injected) when induced events start to occur far away from the boundary of the seismic cloud.

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Earthquake Fault Scaling: Self-Consistent Relating of Rupture Length, Width, Average Displacement, and Moment Release

Cited by 204 publications

References 52 publications

Prediction of the area affected by earthquake-induced landsliding based on seismological parameters

Prediction of the area affected by earthquake-induced landsliding based on seismological parameters

Toward automated directivity estimates in earthquake moment tensor inversion

Analysis of induced seismicity in geothermal reservoirs – An overview

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