Rquake (version 2.5-1)

getregionals: Extract regional events

Description

Extract regional events from a hypocenter list (catalog)

Usage

getregionals(KAT, Mlat, Mlon, rad = 1000, t1 = 1, t2 = 2)

Value

Catalog

Arguments

KAT

catalog list: must include lat, lon and jsec.

Mlat

central latitude

Mlon

central longitude

rad

radius (km)

t1

start time (julian days)

t2

end time (julian days)

Author

Jonathan M. Lees<[e-mail]>

Details

Given an earthquake catalog from PDEs, for example, extract the events that are close to a network in a given time frame. The limited data set may be used to help predict arrival times for known hypocenter locations.

The time jsec is in julian days, i.e. jsec=jd+hr/24+mi/(24*60)+sec/(24*3600) so that they can be compared to t1 and t2.

See Also

RSEIS::Mine.seis, RSEIS::swig

Examples

set.seed(1)
Mlat = 36.00833
Mlon = -117.8048
N = 100
degz = 5
KAT = list(lat=runif(N, Mlat-degz,Mlat+degz) ,
    lon=runif(N,Mlon-degz,Mlon+degz)  )

######  ranfdom times in January
KAT$jsec = runif(N, 1, 30) + runif(N, 0, 24)/(24) + runif(N, 0, 59)/(24*60)

######   extract regional events
localeqs = getregionals(KAT, Mlat, Mlon, rad=200 ,  t1=NULL, t2=NULL)

plot(KAT$lon, KAT$lat, pch=8, col=grey(0.75) )
points(KAT$lon[localeqs], KAT$lat[localeqs], pch=1, col='red', cex=1.5 )