RAPID ESTIMATION OF MAGNITUDE AND Δ FROM B-Δ METHOD FOR MOHAMMAD ABAD EARTHQUAKE

Rapid estimation of the epicentral distance and magnitude of the earthquake is of particular importance for earthquake detection and warning systems. Because an earthquake early warning system should be able to estimate the magnitude, epicenter and hypocenter distance of the earthquake in a few seconds after the P-wave arrival, and based on this information, to warn areas at risk of seismic damage (Odaka at al., 2003; Heidari, 2016). A new and applicable method in earthquake early warning systems is the B-Δ method, which estimate the epicentral distance and magnitude of an earthquake using a single station based on the initial seconds of the p-wave (usually 3 seconds). In the single-station method envelope of vertical component of the acceleration is used to estimate the epicentral distance of the earthquake (Odaka et al., 2003). By Fitting a simple function with the form of y(t)=Bt exp (-At) to the initial part of the waveform envelope, coefficients A and B are determined through the least-squares method and byoverlapping this function on the Logarithmic envelope of vertical component of acceleration in the first 3 seconds of pwave (Noda at al., 2012; Hadi, 2017). B is the slope of the function fitting to the initial part of P wave, A is the change of amplitude over time, Y (t) is the Observed acceleration envelope and t is considered since the arrival of p wave (Mahood, 2016). Then, the magnitude can be estimated from the maximum amplitude observed in a short time interval after the P-wave arrival using an empirical magnitude-amplitude relation.

کلیدواژه ها:

Earthquake Early Warning Systems ، B-Δ method ، Single Station ، magnitude ، epicentral distance