**Keywords:** Local magnitude, Distance correction
function, Grid search.

MEE17706

Supervisor: Tatsuhiko HARA

Country: Bangladesh

Abstractfulltext

We calculated local magnitudes
for events that occurred in and around Bangladesh from January 2007 to December 2010. We retrieved waveform data from the
Incorporated Research Institutions for Seismology (IRIS) Data Management Centre
(DMC) and calculated synthetic Wood-Anderson seismograms. We selected 30 events
for which there are at least 5 waveform data with the high signal to noise
ratio. First we used the distance correction function obtained for southern
California to calculate local magnitudes. We calculated a magnitude residual
which is a difference between a magnitude estimate of each station and the
median magnitude of that event. The hypocentral distance dependence of
magnitude residuals is small, which suggests that the distance correction
function for this area is similar to that of southern California. Then, we
conducted a grid search for the coefficients of the distance correction
function. The set of the coefficients with the minimum root mean square of the
magnitude residuals is similar to that for southern California. We also compared local magnitude estimates to body
wave magnitudes in the ISC catalog to find their correlation.

**Keywords:** Local magnitude, Distance correction
function, Grid search.