Arrival Time Data

mloc uses several types of arrival time data in relocation. The most important data are traditional phase arrival times, which are carried in individual event files formatted in MNF v1.3.The event files used in mloc nearly always must be converted from a different format. Several utility programs for converting from widely-available data formats are provided in /mloc_distribution/mnf_utilities/ and discussed here.

Event files have the filename suffix .mnf. The strongly recommended naming convention is to base the body of the filename on some estimate of the origin time of the event, down to the nearest second:

• YYYYMMDD.HHMM.SS.mnf

It is not important that the origin time represented in the filename be especially accurate, only that it be distinguishable from other events in the cluster.

In addition to the standard set of body wave phases, mloc is able to use Lg arrival times and T-phase arrival times. Commands lgtt and tptt are provided to allow the user to adjust the travel time models used to generate theoretical travel times for these phases.

S-P Data

The MNF v1.3 format can also accommodate S-P (differential phase) times, as described here.

Differential Time Data

Like all relative location techniques, the Hypocentroidal Decomposition algorithm converts observed phase arrival times from different events to common stations into differential times, but mloc was not originally developed to exploit differential time data as a direct input. Such data are now often available through waveform cross-correlation analyses, and a method for using differential time data from other sources has been implemented in mloc, using the MNF v1.5 format.