Source‐Scaling Relations of Interface Subduction Earthquakes for Strong Ground Motion and Tsunami Simulation

Abstract

The recording on high-resolution broadband seismic networks of several great interface subduction earthquakes during the last decade provide an excellent opportunity to extend source-scaling relations to very large magnitudes and to place constraints on the potential range of source parameters for these events. At present, there is a wide range of uncertainty in the median rupture areas predicted for any given seismic moment by current relationships between magnitude and rupture area for subduction interface earthquakes. Our goal is to develop an updated set of earthquake source-scaling relations that will reduce this current large degree of epistemic uncertainty and improve the accuracy of seismic-hazard analysis and the prediction of the strong-motion characteristics and tsunamis of future subduction earthquakes. To achieve this goal, we compiled a database including slip models of interface earthquakes that occurred worldwide with moment magnitudes ranging from M 6.75-9.1. We characterized the seismic sources based on well-established criteria to estimate the asperity areas as well as the average slip on the faults, and we used these parameters to compute an updated set of magnitude scaling relations of the various characteristics of the fault. Additionally, we followed an alternative approach to quantifying slip models for use in developing characteristic slip models of future earthquakes. This involved analyzing the 2D Fourier transforms of the slip functions in the compiled database and deriving a wavenumber spectral model of the slip distribution.

New Empirical Earthquake Source‐Scaling Laws

“…Regardless of whether or not stress drop is scale-invariant, the A ∝ M 2=3 0 scaling has been observed to be consistent with empirical scaling relationships (Wells and Coppersmith, 1994;Somerville et al, 1999;Hanks and Bakun, 2002;Murotani et al, 2008;Leonard, 2010;Skarlatoudis et al, 2016). On the other hand, several studies reported that L grows faster with increasing magnitude (M w > 6) compared to the growth of W (e.g., Mai and Beroza, 2000;Henry and Das, 2001;Papazachos et al, 2004;Blaser et al, 2010;Leonard, 2010).…”

“…Earthquake source-scaling relations provide empirical equations that link observable source parameters to each other. Such scaling relations not only provide insight into earthquake mechanics (e.g., Scholz, 1982;Romanowicz, 1992;Wells and Coppersmith, 1994;Mai and Beroza, 2000;Blaser et al, 2010;Skarlatoudis et al, 2016) but also constitute an essential ingredient in seismic-tsunami-hazard studies (e.g., Stafford, 2014;De Risi and Goda, 2016). However, available databases are limited, whereas uncertainties in the source parameters (primarily rupture length L, rupture width W, average displacement D, and seismic moment M 0 ) are hardly considered.…”

“…Earlier investigations of source-scaling properties based exclusively on rupture models lacked very large magnitude events (e.g., Somerville et al, 1999;Mai and Beroza, 2000). Other studies focused on region-specific scaling relationships (Murotani et al, 2008;Yen and Ma, 2011;Rodríguez-Pérez and Ottemöller, 2013;Ramírez-Gaytán et al, 2014) or a specific fault regime, like subduction events (Murotani et al, 2013;Skarlatoudis et al, 2016;Ye et al, 2016). Thus, there is a need to reexamine earthquake source-scaling properties using a global set of rupture models, considering different faulting regimes and including very large and megathrust events.…”

Spatiotemporal variations of characteristic repeating earthquake sequences along the Middle America Trench in Mexico

“…Stresses were calculated in a 3‐D tensorial way for a half space model by using the formulations given by Okada []. The rupture area, for each analyzed earthquake of the series, is given by an empirical relation, where the aspect ratio explicitly depends on the moment magnitude [ Skarlatoudis et al , , Table 4]. Additionally, we performed the same analysis by using the scaling relations by Wells and Coppersmith [] for comparison.…”

Probabilistic Seismic and Tsunami Hazard Analysis Conditioned on a Megathrust Rupture of the Cascadia Subduction Zone

“…There are several magnitude scaling relationships available in the literature that are derived from global observation of earthquakes on the plate interface of SZ (Papazachos et al, 2004;Strasser et al, 2010;Murotani et al, 2013;Goda et al, 2016;Skarlatoudis et al, 2016). Of these, Skarlatoudis et al (2016) compiled an updated database of interface earthquakes that occurred worldwide in last decade in the major SZs (e.g., 2004 M 9.1 Sumatra, 2010 M 8.8 Chile, 2011M 9.0 Japan earthquake) and proposed new and improved source scaling laws with reduced uncertainty compared to other currently available source scaling laws for subduction earthquakes. Once the appropriate source magnitude and scaling laws are identified, the final step is to perform the earthquake and tsunami simulations for a multiple logic-tree branch.…”