Guest blog: “Photogrammetry for Paleoseismic Trenching” by Nadine Reitman (USGS)

Error analysis

A few weeks ago, Nadine Reitman (USGS) published an interesting paper about the use of Photogrammetry for Paleoseismic Trenching in BSSA. In this guest blog she shares her key findings and explains how to minimise errors without spending too much time measuring control points. Thanks Nadine!

Structure-from-motion (SfM) is now routinely used to construct orthophotos and high-resolution, 3D topographic models of geologic field sites. Here, we turn SfM on its side and use it to construct photomosaics and 3D models of paleoseismic trench exposures. Our results include a workflow for the semi-automated creation of seamless, high resolution photomosaics designed for rapid implementation in a field setting and a new error analysis of SfM models. Continue reading “Guest blog: “Photogrammetry for Paleoseismic Trenching” by Nadine Reitman (USGS)”

Paleoseismology & Tsunami papers – Christmas edition

This is this year’s last issue of my paper round-up, and it includes some pretty interesting stuff. Our Greek colleagues published a report on the liquefaction caused by the 2014 Lefkada earthquakes, just in time with the recent earthquake that hit more or less the same area again (Papathanassiou et al., and see earlier posts here). Long et al. published a paper on iceberg-induced tsunamis, found in the sedimentary record – that’s a great story, isn’t it? Jacobson’s PhD on the Lake Heron Fault (NZ) is an interesting read, and Iván Sunyol’s paper on paleoseismological trenches in Mexico is especially interesting for those who attended the 2012 Morelia meeting. Zhou et al. come up with a great dataset of Pléiades imagery from the El Mayor-Cucapah Quake, Calais et al. have a close look on the northeastern Caribbean, and finally, Kufner et al.’s paper is about the collision between India and Asia deep below the Pamir and Hindu Kush.

Enjoy reading and Merry Christmas!

Continue reading “Paleoseismology & Tsunami papers – Christmas edition”

Guest blog by Marta Ferrater (Uni Barcelona): Lateral Offset Quality Rating along Low Slip Rate Faults

Marta Ferrater from the Universitat de Barcelona did a lot of research on the Alhama de Murcia Fault. Her most recent paper deals with how good we can measure lateral offsets along faults which move only very slowly. This is probably of great interest for many people working on slow faults, so I am glad that she agreed to write the following guest post: Continue reading “Guest blog by Marta Ferrater (Uni Barcelona): Lateral Offset Quality Rating along Low Slip Rate Faults”

A preliminary report on the 17 Nov, 2015, M6.4 South Lefkada earthquake, Ionian Sea, Greece

On 17 November, 2015, a MW6.4 strike-slip earthquake occurred in Lefkada Island, Greece. Lefkada is close to the Cephalonia Transform Fault and has repeatedly experienced strong shaking in the past. The most recent event caused two fatalitites, some damage, and resulted in widespread environmental earthquake effects (EEE). A team of scientists visited the epicentral area after the quake and recorded the damage and the EEEs. They wrote a preliminary report, which can be downloaded here: Lefkada 17 Nov 2015 earthquake report (PDF, 3.9MB).

They document mass movements, damage to buildings, and present first data from seismology, GPS and satellite geodesy.

Thanks to George for sending us the report!

 

New Paper: Paleoseismology & active tectonics in Greece, and how seismic hazard zonation fails

We published a new study dealing with paleoseismological work on the Milesi Fault near Athens, Greece. A slip rate was estimated based on GIS work, mapping, and trenching. Four surface-rupturing earthquakes in the last 4-6 ka were found, and we estimate magnitudes of around M6.2. With these input parameters, we developed a seismic hazard scenario that also takes into account site effects. Our results show that the official seismic hazard zonation in Greece, which is based on instrumental and historical records, contradicts geological data. We also show that extension in this region is not only confined to the Southern Evoikos Gulf graben system, but a significant amount of extension is accommodated by active faults closer to Athens. Continue reading “New Paper: Paleoseismology & active tectonics in Greece, and how seismic hazard zonation fails”

Neotectonics and seismic hazard of the Cusco Region, Peru

Our colleague Carlos Benavente Escóbar from the Instituto Geologico Minero Metalurgico (Peru) brought a book to my attention which was published in 2013: Neotectonics and seismic hazard of the Cusco Region. The book is in Spanish, but you will find it easy to understand what it’s about, because it is full of fascinating images of faults, fault scarps, seismites, liquefaction features, geological maps, and outcrop sketches. Have a look, it’s great! The book can be viewed online for free and is also available for download. Continue reading “Neotectonics and seismic hazard of the Cusco Region, Peru”

New papers on paleoseismology, tsunamis, and the Gorkha Earthquake

A few days ago, SRL published a special issue on the Gorkha earthquakes with lots of interesting papers. I especially like the work of Angster et al. with their impressive photos of the earthquake ground effects. Make sure to download the electronic supplement to this article!

Besides this special issue, a good number of other interesting papers have been published recently on paleoseismicity, active tectonics, seismic hazard, and tsunamis. Among them is Andi’s work on the Ejina basin and Serva et al. with a introduction of using the ESI scale for earthquake hazard assessments. Enjoy reading! Continue reading “New papers on paleoseismology, tsunamis, and the Gorkha Earthquake”

New papers on Paleoseismology and Geoethics

Several new studies have been published recently on old earthquakes and their geological footprint – time to list them and to recommend reading. Additionally, today’s paper digest also lists several articles which are not about paleoseismology, but geoethics. These papers were published in a special volume of GSL. They cover subjects that many paleoseismologists will have dealt with in the past or are likely to deal with in the future  – seismic risk perception, science communication, public outreach, and communicating uncertainties. One paper is dedicated to the L’Aquila trial. I find it very telling that this issue is not open access. Obviously, strengthening “public trust in geosciences” has still a long way to go…

Here are the latest papers:

Continue reading “New papers on Paleoseismology and Geoethics”