震源距離、震央距離、離心率、地心緯度

Sys.time()

[1] “2014-09-29 12:12:38 JST”

Package

library(knitr)
library(Imap) # http://cran.r-project.org/web/packages/Imap/Imap.pdf

Calculation

#lon.1<-readline("Lon1 : ")
#lat.1<-readline("Lat1 : ")
#lon.2<-readline("Lon2 : ")
#lat.2<-readline("Lat2 : ")
lon.1<-139.744858 # e.g. national diet in Japan
lat.1<-35.675888
lon.2<-142.86
lat.2<-38.103333
d<-24 #km
r.a<-6378.137 #radius km
r.b<-6356.7523142 #radius km
#epicentral distance
epi.dis<-gdist(lon.1,lat.1,lon.2,lat.2,units="km",a=r.a*1000,b=r.b*1000,verbose=FALSE)
# http://cran.r-project.org/web/packages/Imap/Imap.pdf#page=2
#geocentric latitude
eccentricity<-(r.a^2-r.b^2)^0.5/r.a
e2<-eccentricity^2
lat.1.gl<-atan((1-e2)*tan(lat.1*pi/180))
lat.2.gl<-atan((1-e2)*tan(lat.2*pi/180))
#hypocentral distance
phi.x<-lat.1.gl
phi.e<-lat.2.gl
lambda.x<-lon.1*pi/180
lambda.e<-lon.2*pi/180
AE<-cos(phi.e)*cos(lambda.e)*(r.a-d)/r.a
BE<-cos(phi.e)*sin(lambda.e)*(r.a-d)/r.a
CE<-sin(phi.e)*(r.a-d)/r.a
AX<-cos(phi.x)*cos(lambda.x)
BX<-cos(phi.x)*sin(lambda.x)
CX<-sin(phi.x)
delta.s<-((AE-AX)^2+(BE-BX)^2+(CE-CX)^2)^0.5
hyp.dis<-delta.s*r.a
cat("Epicentral distance(km)=",epi.dis)
## Epicentral distance(km)= 386.8
cat("Hypocentral Distance(km)",hyp.dis)
## Hypocentral Distance(km) 387.3
cat("Geocentric latitude(degree):point1=",lat.1.gl*180/pi,", point2=",point2=lat.2.gl*180/pi)
## Geocentric latitude(degree):point1= 35.49 , point2= 37.92
cat("Eccentricity=",eccentricity)
## Eccentricity= 0.08182

Reference

正木和明・原徹夫.『緊急地震速報における震度予測式等ソフトウェアの変更』