Triggering of earthquakes during the 2000 Papua New Guinea earthquake sequence

Abstract

A sequence of large earthquakes occurred in the New Britain/New Ireland region of Papua New Guinea in late 2000. The sequence started with a Mw 6.8 earthquake along the New Britain Trench on 29 October. About 20 days later a Mw 8.2 earthquake occurred in the New Ireland region on 16 November and produced large strike‐slip surface displacements and tsunamis. Following the Mw 8.2 event, two large earthquakes (Mw ∼ 7.5) occurred along the nearby New Britain Trench on 16 and 17 November. Furthermore, small triggered events were observed over a wide area outside of the rupture zones of the large earthquakes, with different focal mechanisms from those of the major events. There is likely some mechanism(s) that triggered this remarkable sequence, and we document the details of the spatial and temporal patterns of the events. We investigated if static stress changes can explain the initiation of the large earthquakes and also some groups of triggered smaller events. There are mixed results. The occurrences of the two M ∼ 7.5 major events may be explained by the static stress changes; however, there are also some earthquakes that are not consistent with triggering by static stress changes. There may be multiple mechanisms, including static and dynamic stress changes, that are needed to explain the complicated sequence of earthquakes.

W phase source inversion for moderate to large earthquakes (1990-2010)

“…Δ M w =−0.25). Our solution is similar to USGS CMT ( M w = 7.4), ERI ( M w = 7.3) and Park & Mori (2007) ( M w = 7.4). The observed magnitude difference cannot be fully explained by the dip difference between the GCMT and WCMT solutions (δ wcmt = 26° and δ gcmt = 24°).…”

Are asperity patterns persistent? Implication from large earthquakes in Papua New Guinea

“…Stars and rectangles indicate epicenters and fault planes, respectively, and different colors are used to distinguish the events: blue for the 14 July 1971, light blue for the 26 July 1971, green for the 16 August 1995, red for the 16 November 2000 B, and pink for the 17 November 2000 events. Focal mechanisms are obtained in our studies [this study; Park and Mori , 2007]. Black line indicates the aftershock zone of the 14 July 1971 event, and gray line indicates that of the aftershock zone of the 26 July 1971 event from Lay and Kanamori [1980].…”

“…The inversion procedure was the same as for the 1971 earthquakes. The results for the 2000 events are from Park and Mori [2007], which used the same methodology.…”

“…Two more large earthquakes occurred along the New Britain Trench on 16 and 17 November 2000. The first of these events (M w 7.5) occurred south of New Ireland at 0742:16 UTC on 16 November (designated the 16 November B event by Park and Mori [2007]), and the second (M w 7.4) occurred off the east coast of New Britain region at 2101:56 UTC on 17 November (Figure 2). These earthquakes followed the great New Ireland event (M w 8.2) that occurred at 0454:56 UTC on 16 November 2000 (designated the 16 November A event by Park and Mori [2007]) on a transform fault north of the New Britain Trench.…”

Subduction Zone Characterization of the Northern Papua through the Study of Earthquake History

“…These focal mechanism are consistent with the subduction direction of the oceanic slab beneath the Bird's Head plate. These earthquake doublets are represented by the similarly sized events that occur at nearly the same time and location [10][11][12][13]. Lay and Kanamori [14] reported that such a doublet behavior is a true characteristic of the regions due to the complex tectonic settings.…”