Scaling of Peak Ground Displacement With Seismic Moment Above the Mexican Subduction Thrust

Date: 4/25/2019

Time: 02:30 PM

Room: Puget Sound

Scaling of peak ground displacement (PGD) with the seismic moment (M₀) in the epicentral zone, above the Mexican subduction thrust interface (R_rup ~ 24 km), is of interest in the design of long-period structures and fast estimation of M_w of large/great earthquakes for early tsunami warning. Here we define PGD = [(U_n)_max² + (U_e)_max²]^1/2. We take advantage of the accelerographic network along the Pacific coast of Mexico as well as some sparse continuous GPS (cGPS) and campaign-mode GPS data to establish the PGD – M₀ relationship. Worldwide cGPS recordings of great earthquakes show that in the near-source region the PGD is dominated by the static field. Based on this observation, we compensate for the sparse PGD data of great earthquakes above Mexican subduction thrust by using theoretical static PGD computed using Okada's model. For earthquakes with M₀ ≤ 1.26 x10¹⁸ Nm (M_w≤ 6.0) the point-source, far-field approximation holds and the PGD data follows theoretically expected M₀^2/3 scaling. For great earthquakes (M₀ > 1.26x10²¹ Nm; M_w>8.0), static PGD (≈ dynamic PGD) scales as M₀^1/3. Our preliminary results show that for a given M₀, the relations found predict PGD within a factor of about two.

Presenting Author: Xyoli Perez-Campos

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