Absolute and relative locations of similar events with application

• Main Authors: Ragnar Slunga, Sigurdur Th. Rognvaldsson, Reynir Bodvarsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1995
• Subjects: Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1033.6266; http://gji.oxfordjournals.org/content/123/2/409.full.pdf

It is well known that similar earthquakes, i.e. earthquakes having almost identical waveforms, allow extremely accurate relative timing of the seismic arrivals. This has traditionally been used for achieving accurate relative locations of clusters of similar earthquakes. The arrival time differences between similar events depend not only on their relative location but also on the absolute location of the group. Moving a pair of events 200m while retaining their relative locations can cause a 1 ms change in the time difference between the first arrivals of the events at a station 6km distant. A change in time difference of lms can easily be estimated by cross-correlating the waveforms of the two earthquakes. We use the accurate relative timings to improve absolute locations of groups of similar events, as well as to obtain extremely accurate relative locations. The absolute locations from relative timings are expected to have errors that are independent of the errors associated with locations based on absolute arrival time observations. We analyse data from five earthquake sequences, comprising a total of 96 earthquakes, recorded by a regional network in southern Iceland. One of the clusters is located