Universität zu Köln

Van Noten, Koen ORCID: 0000-0001-8933-4426, Lecocq, Thomas ORCID: 0000-0002-4988-6477, Sira, Christophe, Hinzen, Klaus-G. and Camelbeeck, Thierry (2017). Path and site effects deduced from merged transfrontier internet macroseismic data of two recent M4 earthquakes in northwest Europe using a grid cell approach. Solid Earth, 8 (2). S. 453 - 478. GOTTINGEN: COPERNICUS GESELLSCHAFT MBH. ISSN 1869-9529

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Abstract

The online collection of earthquake reports in Europe is strongly fragmented across numerous seismological agencies. This paper demonstrates how collecting and merging online institutional macroseismic data strongly improves the density of observations and the quality of intensity shaking maps. Instead of using ZIP code Community Internet Intensity Maps, we geocode individual response addresses for location improvement, assign intensities to grouped answers within 100 km2 grid cells, and generate intensity attenuation relations from the grid cell intensities. Grid cell intensity maps are less subjective and illustrate a more homogeneous intensity distribution than communal ZIP code intensity maps. Using grid cells for ground motion analysis offers an advanced method for exchanging transfrontier equal-area intensity data without sharing any personal information. The applicability of the method is demonstrated on the felt responses of two clearly felt earthquakes: the 8 September 2011 M-L 4.3 (M-w 3.7) Goch (Germany) and the 22 May 2015 M-L 4.2 (M-w 3.7) Ramsgate (UK) earthquakes. Both events resulted in a non-circular distribution of intensities which is not explained by geometrical amplitude attenuation alone but illustrates an important low-pass filtering due to the sedimentary cover above the Anglo-Brabant Massif and in the Lower Rhine Graben. Our study illustrates the effect of increasing bedrock depth on intensity attenuation and the importance of the WNW-ESE Caledonian structural axis of the Anglo-Brabant Massif for seismic wave propagation. Seismic waves are less attenuated -high Q -along the strike of a tectonic structure but are more strongly attenuated - low Q-perpendicular to this structure, particularly when they cross rheologically different seismotectonic units separated by crustal-rooted faults.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Van Noten, Koen UNSPECIFIED orcid.org/0000-0001-8933-4426 UNSPECIFIED Lecocq, Thomas UNSPECIFIED orcid.org/0000-0002-4988-6477 UNSPECIFIED Sira, Christophe UNSPECIFIED UNSPECIFIED UNSPECIFIED Hinzen, Klaus-G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Camelbeeck, Thierry UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-234060
DOI:	10.5194/se-8-453-2017
Journal or Publication Title:	Solid Earth
Volume:	8
Number:	2
Page Range:	S. 453 - 478
Date:	2017
Publisher:	COPERNICUS GESELLSCHAFT MBH
Place of Publication:	GOTTINGEN
ISSN:	1869-9529
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language 1992 ROERMOND EARTHQUAKE; NORTHERN RHINE AREA; GROUND MOTIONS; INTENSITY DATA; FOLKESTONE; SEISMICITY; GERMANY; GORKHA; GRABEN; NEPAL Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23406