WP 4.1 Source mechanisms and fault dimensions of the June 17 and June 21 earthquakes determined from inversion of teleseismic body waves and from mapping of aftershocks

Start date or starting event:

M0

Lead contractor:

IMOR

Participants:

IMOR, UU

1

Objectives:

Determine the source mechanisms and fault dimensions of the two large earthquakes on June 17 (J17) and June 21 (J21), using local and teleseismic body waves. That is:

         Obtain a point-source moment tensor solution and source-time function for each of the two large events, as well as search for source directivity in their seismic data.

          Define the locations, dimensions and possible sub-fault details in the fault planes of the J17  and J21 earthquakes, by relatively locating the thousands of aftershocks on each of the two faults.

          Map the post-seismic slip as a function of location and time on the two large faults in order to understand the evolution of the post-seismic stress.

2

Inputs:

         Broad-band seismic body waves from J17 and J21, recorded at teleseismic distances on GSN, GEOSCOPE and other available networks.

         Around seven thousand microearthquakes on each of the two major faults, recorded by the SIL seismic network in the weeks and months following the two large earthquakes.

 

Methodology / work description:

         P- and SH-waves from J17 and J21, recorded on broad-band stations at teleseismic (30-90) distances will be inverted to obtain a moment tensor and source-time function for each earthquake.

         Nearly half of the approximately fourteen thousand microearthquakes have yet to be interactively analyzed, to give a good starting location and mechanism for each event. The improved locations will be fed into a multievent relative location algorithm, in order to map the fault dimensions and finer subfault details of J17 and J21.

          Combined interpretation of the hypocenter distribution and the possible fault-plane solutions of the individual microearthquakes, in order to study the finer details of post-seismic slip on the two large faults, as a function of time and space.

3

Deliverables including cost of deliverable as percentage of total cost of the proposed project:

D56

A point-source moment tensor solution and source-time function for the earthquakes of June 17 and June 21, 2000.

M3    Re  PU  0,6%

D57

Article on the fault dimensions and finer details of possible subfaults, as outlined by the microearthquake distribution.  Post-seismic slip-direction as a function of location on the two main faults.

M18  Re  PU  4,0%

                                                                          

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Milestones: Delivery of the above items at the date indicated.