getregionals {Rquake}

Extract regional events

Description

Extract regional events from a hypocenter list (catalog)

Usage

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

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)

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.

Value

Catalog

Author(s)

Jonathan M. Lees<[e-mail]>

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 )