HAZDist

HAZDist provides a set of R wrapper functions around the distance calculation routines from Norman Abrahamson's HAZ Fortran code. The package is useful when computing fault–to–site distances required by ground motion prediction equations (GMPEs).

Features

• SetFltBottom – compute the bottom coordinates of a fault plane.
• ConvertCoordinates2 – convert geographic coordinates to a local Cartesian system.
• calcfltgrid – create a fault grid used in distance calculations.
• CalcDist – return common GMPE distance measures such as Rjb, Rrup, Rx, Ry and Ry0.
• getfaultcoord – extract fault geometry information from a spatial data frame.
• getfaultdist – high level helper to compute distances from a fault to one or more sites.

Installation

install.packages("devtools")
# install from GitHub
devtools::install_github("personlin/HAZDist")

Example

The package ships with a sample spatial data set FT describing the Shanchiao fault. The following code demonstrates how to compute the fault–to–site distances for a single location:

library(HAZDist)

# load example fault data
data(FT)

# extract geometry for the first fault
fault <- getfaultcoord(
  faultlines   = FT,
  id           = 1,
  c.id         = "ID",
  c.fault.top  = "DEPTH1_KM",
  c.fault.thick= "WIDTH_KM",
  c.dip        = "FAULT_DIP1"
)

# coordinates of the site (longitude, latitude)
site <- data.frame(x = 121.001, y = 24.7794)

# compute distance metrics
getfaultdist(fault, site, seismoDepth = 0)

Data

FT is a spatial data frame containing the geometry and attributes of part of the Shanchiao fault system. The data include columns such as FAULT_NAME, FAULT_TYPE, LENGTH_KM, FAULT_DIP1, DEPTH1_KM and WIDTH_KM.

License

HAZDist is released under the GPL (>= 3) license.