travel

README

travel

travel is a Go library for estimating seismic-wave travel times from the published AK135 tables. It provides a compact, table-driven API for common phases such as P, PcP, PKPab, PKPbc, PKIKP, S, ScP, ScS, SKP, SKS, and SKIKS.

Features

• Create an AK135 model with NewAK135
• Estimate travel times for all supported phases in one call
• Optionally interpolate travel times in distance and source depth
• Convert geographic coordinates to angular distance with helper functions

Installation

go get github.com/bclswl0827/travel

Quick start

package main

import (
    "fmt"

    "github.com/bclswl0827/travel"
)

func main() {
    model, err := travel.NewAK135()
    if err != nil {
        panic(err)
    }

    estimation := model.Estimate(
        travel.GetDeltaByCoordinates(28.25, 104.87, 29.81, 106.40),
        10,
        true,
    )

    fmt.Printf("P travel time: %v\n", estimation.P.Duration)
}

API notes

• Estimate(delta, depth, interpolate) returns a struct containing one result per supported phase.
• Each phase result is a pointer to a TravelTimeEntry when the phase exists for the requested distance and depth; otherwise it is nil.
• The Duration field is a Go time.Duration (nanoseconds), and Slowness is reported in seconds per degree.
• Interpolation follows TauP's ray-parameter rule for distance and uses linear interpolation in depth between adjacent published table depths.
• The package does not trace rays through a velocity model or return multiple arrivals for a single phase; it is intentionally limited to the published AK135 tables.

License

The original software source code is licensed under Apache-2.0.

The AK135 numerical data under resource/data are derived from B. L. N. Kennett's Seismological Tables: ak135 and are not claimed to be licensed under Apache-2.0.

See resource/data/README.md.

Documentation

Index

• Constants
• func GetDeltaByCoordinates(lat1, lon1, lat2, lon2 float64) float64
• func GetDistanceByCoordinates(lat1, lon1, lat2, lon2 float64) float64
• func GetDistanceByDelta(delta float64) float64
• type AK135
  • func NewAK135() (*AK135, error)
  • func (p *AK135) Estimate(delta, depth float64, interpolate bool) Estimation
• type Estimation
• type IPhase

Constants

const RADIUS_EARTH_KM = 6371.0

Functions

func GetDeltaByCoordinates

func GetDeltaByCoordinates(lat1, lon1, lat2, lon2 float64) float64

func GetDistanceByCoordinates

func GetDistanceByCoordinates(lat1, lon1, lat2, lon2 float64) float64

func GetDistanceByDelta

func GetDistanceByDelta(delta float64) float64

Types

type AK135

type AK135 struct {
	P     IPhase
	PcP   IPhase
	PKPab IPhase
	PKPbc IPhase
	PKIKP IPhase
	S     IPhase
	ScP   IPhase
	ScS   IPhase
	SKP   IPhase
	SKS   IPhase
	SKIKS IPhase
}

func NewAK135

func NewAK135() (*AK135, error)

func (*AK135) Estimate

func (p *AK135) Estimate(delta, depth float64, interpolate bool) Estimation

type Estimation

type Estimation struct {
	P     *resource.TravelTimeEntry
	PcP   *resource.TravelTimeEntry
	PKPab *resource.TravelTimeEntry
	PKPbc *resource.TravelTimeEntry
	PKIKP *resource.TravelTimeEntry
	S     *resource.TravelTimeEntry
	ScP   *resource.TravelTimeEntry
	ScS   *resource.TravelTimeEntry
	SKP   *resource.TravelTimeEntry
	SKS   *resource.TravelTimeEntry
	SKIKS *resource.TravelTimeEntry
}

type IPhase

type IPhase interface {
	Name() string
	Boundary() (minDelta, maxDelta, minDepth, maxDepth float64)
	Estimate(delta, depth float64, interpolate bool) (result resource.TravelTimeEntry, err error)
}