dorsal/arxiv
View SchemaApparent Clustering and Apparent Background Earthquakes Biased by Undetected Seismicity
| Authors | D. Sornette, M. J. Werner |
|---|---|
| Categories | |
| ArXiv ID | physics/0501049 |
| URL | https://arxiv.org/abs/physics/0501049 |
| DOI | 10.1029/2005JB003621 |
| Journal | J. Geophys. Res. Vol. 110, B09303 (2005) |
Abstract
In models of triggered seismicity and in their inversion with empirical data, the detection threshold m_d is commonly equated to the magnitude m_0 of the smallest triggering earthquake. This unjustified assumption neglects the possibility of shocks below the detection threshold triggering observable events. We introduce a formalism that distinguishes between the detection threshold m_d and the minimum triggering earthquake m_0 < m_d. By considering the branching structure of one complete cascade of triggered events, we derive the apparent branching ratio n_a (which is the apparent fraction of aftershocks in a given catalog) and the apparent background source S_a that are observed when only the structure above the detection threshold m_d is known due to the presence of smaller undetected events that are capable of triggering larger events. If earthquake triggering is controlled in large part by the smallest magnitudes as several recent analyses have shown, this implies that previous estimates of the clustering parameters may significantly underestimate the true values: for instance, an observed fraction of 55% of aftershocks is renormalized into a true value of 75% of triggered events.
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"abstract": "In models of triggered seismicity and in their inversion with empirical data,\nthe detection threshold m_d is commonly equated to the magnitude m_0 of the\nsmallest triggering earthquake. This unjustified assumption neglects the\npossibility of shocks below the detection threshold triggering observable\nevents. We introduce a formalism that distinguishes between the detection\nthreshold m_d and the minimum triggering earthquake m_0 \u003c m_d. By considering\nthe branching structure of one complete cascade of triggered events, we derive\nthe apparent branching ratio n_a (which is the apparent fraction of aftershocks\nin a given catalog) and the apparent background source S_a that are observed\nwhen only the structure above the detection threshold m_d is known due to the\npresence of smaller undetected events that are capable of triggering larger\nevents. If earthquake triggering is controlled in large part by the smallest\nmagnitudes as several recent analyses have shown, this implies that previous\nestimates of the clustering parameters may significantly underestimate the true\nvalues: for instance, an observed fraction of 55% of aftershocks is\nrenormalized into a true value of 75% of triggered events.",
"arxiv_id": "physics/0501049",
"authors": [
"D. Sornette",
"M. J. Werner"
],
"categories": [
"physics.geo-ph"
],
"doi": "10.1029/2005JB003621",
"journal_ref": "J. Geophys. Res. Vol. 110, B09303 (2005)",
"title": "Apparent Clustering and Apparent Background Earthquakes Biased by Undetected Seismicity",
"url": "https://arxiv.org/abs/physics/0501049"
},
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