Spatial variations in the frequency-magnitude distribution of earthquakes in the southwestern Okinawa Trough

In this study, the geospatial frequency–magnitude distribution (FMD) b-value images of the prospect sources of upcoming earthquakes were investigated along the Indonesian Sunda Margin (ISM) that strikes parallel to and near the Indonesian Island chain. After enhancing the completeness and stability of the earthquake catalogue, the seismicity data were separated according to their seismotectonic setting into shallow crustal and Intraslab earthquakes. In order to verify the spatial relationship between the b-values and the occurrence of subsequent major earthquakes, the complete shallow crustal seismicity dataset (1980–2005) was truncated into the 1980–2000 sub-dataset. Utilizing the suitable assumption of fixed-number of earthquakes, retrospective tests of both the complete and truncated datasets supported that areas of comparatively low b-values could reasonably be expected to predict likely hypocenters of future earthquakes. As a result, the present-day distributions of b-values derived from the complete (1980–2005) shallow crustal and Intraslab seismicity datasets revealed eight and six earthquake-prone areas, respectively, along the ISM. Since most of these high risk areas proposed here are quite close to the major cities of Indonesia, attention should be paid and mitigation plans should be developed for both seismic and tsunami hazards.

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Earthquake frequency-magnitude distribution and fractal dimension in mainland Southeast Asia

Earth Planets and Space ◽

10.1186/1880-5981-66-8 ◽

2014 ◽

Vol 66 (1) ◽

pp. 8 ◽

Cited By ~ 13

Author(s):

Santi Pailoplee ◽

Montri Choowong

Keyword(s):

Fractal Dimension ◽

Southeast Asia ◽

Magnitude Distribution ◽

Earthquake Frequency ◽

Frequency Magnitude Distribution ◽

Frequency Magnitude ◽

Mainland Southeast Asia

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Measurement of the head impacts in a sub-elite Australian Rules football team with an instrumented patch: An exploratory analysis

International Journal of Sports Science & Coaching ◽

10.1177/1747954117710512 ◽

2017 ◽

Vol 12 (3) ◽

pp. 359-370 ◽

Cited By ~ 13

Author(s):

D King ◽

M Hecimovich ◽

T Clark ◽

C Gissane

Keyword(s):

Cohort Analysis ◽

Medical Personnel ◽

Magnitude Distribution ◽

Head Impacts ◽

Australian Football League ◽

Football Team ◽

Australian Rules Football ◽

Australian Football ◽

Frequency Magnitude Distribution ◽

Frequency Magnitude

An investigation was made of the frequency, magnitude, and distribution of head impacts in Australian Football League players over a season of matches. In a prospective cohort analysis of impact magnitude, frequency, and distribution on data collected with a wireless head impact sensor worn behind the ear of 23 players, a total of 4903 impacts were recorded. Players experienced on average 407 ± 143 impacts over the duration of the study resulting in 30 ± 38 impacts per-player per-match. Linear accelerations ranged from 10 g to 153 g with a mean, median, and 95th percentile value of 17 g, 13 g, and 40 g, respectively. Rotational accelerations ranged from 130 rad/s2 to 21,890 rad/s2 with a mean, median, and 95th percentile value of 2426 rad/s2, 1556 rad/s2, and 7571 rad/s2, respectively. This study obtained initial measurements on the frequency, magnitude, distribution, and risk weighted exposure of head impacts in Australia Rules Football in order to better inform medical personnel in the identification and evaluation of at-risk players for concussion. The location of impacts varied considerably with the back of the head recording more total impacts than the front, side, and top. Midfielders sustained more impacts per-player, per-match, and had higher median resultant linear accelerations than forwards and defenders. The results of this study, in which most impacts were within the low severity limit for linear, rotational, HITSP, and RWECP, indicate that Australian Rules football needs to include more encompassing methods of examination of player exposure.

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Microseismic feasibility study: detection of small magnitude events (Ml<0.0) for mapping active faults in the Betic Cordillera (Spain)

Annals of Geophysics ◽

10.4401/ag-4635 ◽

2010 ◽

Vol 52 (2) ◽

Author(s):

Martin Häge ◽

Manfred Joswig

Keyword(s):

Feasibility Study ◽

Active Faults ◽

Field Measurements ◽

Small Magnitude ◽

Magnitude Distribution ◽

Short Period ◽

Actual Field ◽

Frequency Magnitude Distribution ◽

Central Station ◽

Frequency Magnitude

We present the results of the first application of the newly developed concept «Nanoseismic Monitoring» on active faults in the region close to Murcia, Spain. The aim of this microseismic feasibility study is to test if it is possible to record small magnitude events (ML<0.0) within a short period of time with surface installations and to investigate if these events are related to the regional catalog in terms of amount of events. The seismic monitoring was performed with one small array called the Seismic Navigating System. It consists of one central three component and three one component seismometers arranged tripartitely around the central station. In the measurement period of two nights at two different sites we were able to detect 19 microearthquakes down to ML = -2.6. The results correlate well with the frequency-magnitude distribution of the regional bulletin. This in turn will allow for estimation of monitoring rates before actual field measurements just from bulletin data. Given an activity rate of 5 to 10 events per night one may map active fault zones within just a few weeks of field campaign.

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A grid-based b-value approximation through Southern and Northern Norway: preliminary results

10.5194/egusphere-egu21-9664 ◽

2021 ◽

Author(s):

Rodrigo Estay ◽

Claudia Pavez

Keyword(s):

B Value ◽

Seismic Events ◽

Online Database ◽

Magnitude Of Completeness ◽

Stress Regime ◽

Magnitude Distribution ◽

The Mean ◽

Frequency Magnitude Distribution ◽

Frequency Magnitude ◽

Grid Based

The Gutenberg &#8211; Richter&#8217;s b-value is commonly used to analyze the frequency-magnitude distribution of earthquakes, describing the proportion of small and large seismic events as the first estimation of seismic hazard. Additionally, the b-value has been used as a stress meter, giving some insights into the stress regime in different regions around the world. In this research, a grid-based spatial distribution for the b &#8211; value was estimated in three different areas of Norway: northern (74&#176;-81&#176; N/ 12&#176;-26&#176; E), southern (57&#176;-64&#176;N/3&#176;-12&#176; E), and the ridge zones of Mohns and Knipovich. For this, we used a complete catalog from the years 2000 to 2019, which was obtained from the Norwegian National Seismic Network online database. The magnitude of completeness was estimated separately for each zone both in time and space, covering a total area of ~425,000 km2. Our results show a regional variation of the mean b-value for northern (bnorth = 0.79) and southern (bsouth = 1.03) Norway, and the Ridge (bridge = 0.73), which can be interpreted in terms of the predominant stress regime in the different zones. So far, a few calculations regarding the b-value were previously done in Norway to analyze local intraplate sequences. Then, according to our knowledge, this research corresponds to the first estimation of a regional spatial variation of the b &#8211; value in the country.

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