Patterns in seismology and palaeoseismology, and their application in long-term hazard assessments - the Swedish case in view of nuclear waste management

From Nuclear Heritage
Revision as of 12:19, 29 November 2013 by Falk (talk | contribs)
Jump to navigationJump to search

First publication of this report in Pattern Recognition in Physics (PRP).

Pattern Recogn. Phys., 1, 75–89, 2013
www.pattern-recogn-phys.net/1/75/2013/
doi:10.5194/prp-1-75-2013
©Author(s) 2013. CC Attribution 3.0 License.
N.-A. Mörner
Paleogeophysics & Geodynamics, Rösundavägen 17, 13336 Saltsjöbaden, Sweden
Correspondence to:
N.-A. Mörner (morner AT pog.nu[1])
Received: 12 May 2013 – Accepted: 1 July 2013 – Published: 24 July 2013


Figure 1. Means of recording seismic events over past and present time (from Mörner, 2011). For meaningful seismic hazard assessments, the seismic records must be combined with palaeoseismic analyses. Meaningful long-term predictions must be based on palaeoseismic data of high quality and completeness.

Abstract

Seismic events are recorded by instruments, historical notes and observational criteria in geology and archaeology. Those records form a pattern of events. From these patterns, we may assess the future seismic hazard. The time window of a recorded pattern and its completeness set the frames of the assessments. Whilst instrumental records in seismology only cover decades up to a century, archaeoseismology covers thousands of years and palaeoseismology tens of thousands of years. In Sweden, covered by ice during the Last Ice Age, the palaeoseismic data cover some 13 000 yr. The nuclear industries in Sweden and Finland claim that the high-level nuclear waste can be buried in the bedrock under full safety for, at least, 100 000 yr. It seems hard, if on the whole possible, to make such assessments from the short periods of pattern recognition in seismology (< 100 yr) and palaeoseismology (∼ 13 000 yr). All assessments seem to become meaningless, maybe even misleading. In this situation, we must restrict ourselves from making too optimistic an assessment. As some sort of minimum level of the seismic hazard, one may multiply the recorded seismic hazard over the past 10 000 yr by 10, in order to cover the required minimum time of isolation of the toxic waste from the biosphere of 100 000 yr.


Introduction

In China, we have a historical documentation of seismic events for the last 4250 yr (Wang, 1987; Mörner, 1989). This is, of course, quite unique. In most other areas, we have fragments recorded over a few hundred years, or so. The recording by permanent instruments (seismographs) began at the end of the 19th century. This means that instrumental records are limited to the last half-century to the last century.

The seismic destruction of monuments (i.e. archaeoseismology) goes back a few thousands of years (e.g. Sintubin, 2011; Stiros and Jones, 1996). Sometimes, mythology may provide information of past seismic events (Piccardi and Masse, 2007).

Palaeoseismology (or earthquake geology) refers to seismic effects as recorded in geology (McCalpin, 2009; Mörner, 2003; Reicherter et al., 2009; Silva et al., 2011). This implies that the records may date to any part of the geological time. With respect to seismic hazard assessment, we must, however, focus on the continual records of the Late Quaternary, especially the Holocene (e.g. Rockwell, 2010).

When we make seismic hazard assessments, there must be some sort of relation between the time frame of observation and the time frame of extrapolation. Seismology is good for assessment of the hazard of the near future – i.e. decades up to a century. When we are forced to make assessments for a longer time period, we have to rely on palaeoseismology (Fig. 1).

Figure 1. Means of recording seismic events over past and present time (from Mörner, 2011). For meaningful seismic hazard assessments, the seismic records must be combined with palaeoseismic analyses. Meaningful long-term predictions must be based on palaeoseismic data of high quality and completeness.

In the case of nuclear waste handling, the time span needed to be covered by seismic hazard assessment increases to the immense period of 100 000 yr or more (Mörner, 2012a). The question is whether we, by this, have not extended our predictions "in absurdum" (Mörner, 2001). The present paper will address this question. IAEA (2010) has tried to establish criteria and recommendations for seismic hazard assessment in association with nuclear power installations. The focus is on the installation



  1. For protection against automatical email address robots searching for addresses to send spam to them this email address has been made unreadable for them. To get a correct mail address you have to displace "AT" by the @-symbol.