10:45 AM - 11:00 AM
[S05-2-02] Modern methods applied to historical seismograms: Perspective and examples
invited
The long recurrence times characteristic of major earthquakes (typically one
to several centuries) result in severe undersampling of the Earth's seismicity
as documented by digital seismic networks (at most 40 years old), or even
their immediate predecessor, the WWSSN (55 years old).
Yet, crucial information can be extracted
using variations of modern techniques routinely applied to digital data.
We present a review of these algorithms, notably the PDFM moment tensor
inversion and the application of energy- moment discriminants. We will review
several examples, including the resolution of the "twin eights" of 17 August
1906, the quantification of the slowness parameters of the 1932 Manzanillo,
1947 Hikurangi and 1934 Santa Cruz tsunami earthquakes, and focal mechanism solutions for
two major plate boundary events, on 01 May 1915 in the Kuril Islands and
26 June 1941 in the Andaman Islands, which are both shown to be incompatible
with a shallow-angle thrust geometry. Application to large normal faulting
intraplate earthquakes (e.g., Sanriku, 02 March 1933) is particularly
important given the probably longer recurrence times of such events,
which are thus even more undersampled by modern records.
to several centuries) result in severe undersampling of the Earth's seismicity
as documented by digital seismic networks (at most 40 years old), or even
their immediate predecessor, the WWSSN (55 years old).
Yet, crucial information can be extracted
using variations of modern techniques routinely applied to digital data.
We present a review of these algorithms, notably the PDFM moment tensor
inversion and the application of energy- moment discriminants. We will review
several examples, including the resolution of the "twin eights" of 17 August
1906, the quantification of the slowness parameters of the 1932 Manzanillo,
1947 Hikurangi and 1934 Santa Cruz tsunami earthquakes, and focal mechanism solutions for
two major plate boundary events, on 01 May 1915 in the Kuril Islands and
26 June 1941 in the Andaman Islands, which are both shown to be incompatible
with a shallow-angle thrust geometry. Application to large normal faulting
intraplate earthquakes (e.g., Sanriku, 02 March 1933) is particularly
important given the probably longer recurrence times of such events,
which are thus even more undersampled by modern records.