- © 2014 by the Seismological Society of America
Seismogenesis ends when an earthquake occurs, then the process recommences. The Cox (1972) model relates time that passes before an event occurs to covariates associated with that time. This is developed into a proportional seismic‐hazard model of earthquake elapsed time and is used to delve into the temporal and spatial complexity of Indonesian seismicity in different tectonic environments. Moment magnitudes Mw≥7.0 are accepted, being more closely causally related to major tectonic faults than is the populous 5.0≤Mw<7.0 seismicity. Eight zones are modeled, spanning the subduction between the Australian and Sunda plates, the back‐arc of Java and Bali, the arc–arc collision of the Molucca Sea plate, and the Sumatran fault. Results are directed toward short‐ to mid‐term forecast periods. Example results for 5‐ and 10‐year forecast periods extend from the lowest expectations for the Sumatran fault (37.6% and 50.1%, respectively) to the highest for Molucca Sea plate (76.4% and 82.2%, respectively). These earthquakes are demonstrably time dependent; their seismogenesis has memory. The hazard trends from empirical function analysis of large Indonesian earthquakes decrease with time.
Indonesia has very high seismicity. Between 1900 and September 2011, the period of our analysis, 642 strong earthquakes (Mw≥6.0) have occurred, including 115 large earthquakes (Mw≥7.0) and seven great earthquakes (Mw≥8.0). The most obvious tectonic feature is subduction involving the major Sunda trench (Petersen et al., 2004). There is also back‐arc seismicity, arc–arc collision in the Molucca Sea plate region, and the Sumatran strike‐slip fault (Fig. 1). The Sumatra‐Andaman 2004 earthquake (Mw 9.1) is the third largest earthquake globally since 1900; its subsequent tsunami killed nearly 300,000 people, with heavy property losses in widespread areas around the Indian Ocean. It triggered a great earthquake (Sumatra 28 March 2005, Mw 8.7) in the Sunda …