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Summarized Report on Northern Sumatra, Indonesia earthquake
2005 March 28, 16:09:36 (UTC)
Farahbod. A.M. and Mokhtari, M.
Source parameters
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Date/Time: 2005/03/28
16:09:36 (UT)
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Lat,Lon,Depth: 2.076N
97.013E 27 km
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Strike, Dip, Rake: (320,
12, 104)
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Mo :1.3x10**22 Nm
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Mw: 8.7
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Source duration: 120s
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Dmax: 12 m
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Reference: (Tokyo
University)
Break stages
After Wahyu
Triyoso
Tsunami Magnitude
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Mt = log H2 + log X +
5.55(Ref. Abe, K., Phys. Earth Planet. Inter., 27, 194-205, 1981)
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Mt: Tsunami magnitude
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H2: Maximum
crest-to-trough amplitude on tide gage record in m
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X: Distance from epicenter
to station along the shortest oceanic path in km
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Mt: 8.45+/-0.21
Characteristics of the recent event
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The 28 March quake
occurred on the same fault, but on the portion that did not rupture in the
26 December quake. Energy propagated mainly to the south in the 28 March
quake and to the north in the 26 December quake.
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At least one of the
elements besides magnitude required to generate a tsunami was missing:
Possibly either the lack of a sufficient vertical component of fault motion,
or a configuration of the ocean bottom in the epicentral region that
prevented uniform uplift over a broad area, as in the 26 December quake.
Damages
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In the case of the 28
March quake, the earthquake was the cause of damage and deaths, not a
tsunami. The opposite was true for the 26 December quake.
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Because the epicenter was
much closer to urban areas of Indonesia in the 28 March quake, an estimated
2,000 people (at least 1000 in Nias) were killed and damage and destruction
were wide spread.
Intensity
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Felt (VI) at Banda Aceh
and (V) at Medan.
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Felt (IV) along the west
coast of Malaysia; (IV) at Bangkok and (III) at Phuket, Thailand; (III) at
Singapore; (III) at Male, Maldives. The quake was also felt in the Andaman
and Nicobar Islands, India and in Sri Lanka (Source: NEIC).
(Courtesy Max Wyss)
Seismograms Recorded at Broadband Seismic Network of IIEES for 2005 March 28
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