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.

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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.