Seismica’s Post

This USGS/SCEC Community Stress Drop validation study by Baltay et al. invites researchers worldwide to help resolve disagreements in stress drop estimations using the common 2019 M7.1 Ridgecrest earthquake dataset. Read more: https://lnkd.in/dSwChHFC The stress release (or stress drop) during an earthquake provides information on how geologic forces are converted to ground-shaking energy and controls the conditions under which an earthquake will continue to increase in size or trigger earthquakes nearby. Stress drop is also an important element of seismic hazard mapping and building design since stress drop is a predictor of the level of ground shaking – a higher stress drop means more ground shaking. Unfortunately, estimates made in different studies or by different researchers have large systematic and random differences, rendering them not as useful for ground-shaking prediction as we would hope. This new Community Stress Drop Validation Study by Baltay et al. aims to understand where the differences and similarities in stress drop come from, and then work with the wider user community to develop improved methods for characterizing earthquake rupture. They have distributed a public dataset of earthquake recordings of aftershocks of the 2019 Ridgecrest, California earthquake, and all interested scientists from the international community are invited to analyze the same earthquakes and compare and contrast their results. #Seismology #EarthquakeScience #peerreviewed #DiamondOpenAccess #Earthquake #OpenAccess #OpenScience

🌍 Groundbreaking Discovery in Earthquake Research! 🌍 Not my field but definitely news worth sharing: a significant advancement in earthquake research titled "Variations of Whole–Adria Microplate Motion During the Interseismic Phase Preceding the MW 6.3, 6 April 2009 L’Aquila (Italy) Earthquake" by Giampiero Iaffaldano and William K. Kalum. 🔍 Key Findings: Dynamic Plate Movements: This study reveals that the motion of the Adria microplate slowed by around 20% in the years before the 2009 L’Aquila earthquake, challenging the long-standing belief that tectonic plate motions remain steady over earthquake cycles. Interseismic Influence: The slowdown is linked to interseismic stress accumulation, suggesting that earthquake cycles significantly impact plate motions. Advanced GNSS Data Analysis: By utilizing GNSS data from Central and Northern Italy, the researchers demonstrated that the required torque to induce this slowdown aligns with the stress variations preceding the earthquake. 📈 Implications: This research challenges traditional earthquake genesis and seismic potential models, offering new perspectives for assessing seismic hazards. The findings underscore the critical importance of continuous monitoring and advanced modelling in understanding and predicting earthquake behaviour. This discovery is a major step forward in earthquake research, potentially contributing to saving lives in seismic regions by improving our understanding of earthquake precursors. 🔗 Read the full publication here: https://lnkd.in/dAdEM4Hy #Geoscience #EarthquakeResearch #TectonicPlates #SeismicHazard #ScientificDiscovery

"The earth is a great earthquake machine: it is constantly working, constantly shaking, constantly making quakes." On April 26, 1900, Charles Francis Richter, the American seismologist and physicist, was born. Richter is best known for developing the Richter scale, a logarithmic scale used to measure the magnitude of earthquakes. This groundbreaking invention revolutionized the field of seismology and became a crucial tool for monitoring and understanding seismic activity worldwide. Richter's contributions to seismology were instrumental in advancing our understanding of earthquakes and their potential impacts. The Richter scale, introduced in 1935, provided a quantitative measure of an earthquake's magnitude, allowing for more accurate comparisons and assessments of seismic events. This innovation played a vital role in earthquake preparedness, risk assessment, and the development of seismic-resistant structures. In addition to his work on the Richter scale, Richter made significant contributions to the study of earthquake mechanisms and the propagation of seismic waves. His research helped lay the foundation for modern seismology and influenced the development of earthquake early warning systems. Richter's most well-known quote reflects his dedication to scientific inquiry and the pursuit of knowledge: "The earth is a great earthquake machine: it is constantly working, constantly shaking, constantly making quakes." Through his groundbreaking inventions and scientific contributions, Charles Francis Richter left an indelible mark on the field of seismology and played a crucial role in enhancing our understanding of the Earth's seismic activity, ultimately contributing to the safety and preparedness of communities around the world. #CharlesFrancisRichter #RichterScale #EarthquakeMagnitude #SeismologyPioneer #GroundbreakingInvention #EarthquakeScience #SeismicActivity #EarthquakeMachine #SeismicWaves #EarthquakePreparedness #RiskAssessment #SeismicResistantStructures #EarthquakeEarlyWarning #ScientificInquiry #PursuitOfKnowledge #SeismologyHistory #SeismicMonitoring #EarthquakeImpacts #NaturalDisasters #DisasterManagement #EarthScienceHeroes #ScienceInnovators #STEMPioneers #BreakthroughResearch #SeismicDataAnalysis #EarthquakeForecasting #TectonicPlateMovements #SeismicHazards #EarthquakeResilientCities #EarthquakeSafety #SeismicRiskMitigation #EarthquakeAwareness #NaturalPhenomena #GeologicalProcesses #EarthquakeEducation #SeismologyExploration #EarthquakeResilience #SeismicEngineering #GroundMotionModeling #EarthquakeSimulations #SeismicRiskMapping #EarthquakeResponsePlanning #DisasterResilience #SeismicRetrofitting #EarthquakeRecovery #SeismicMonuments #EarthquakeMemorials #SeismicLegacies

📢 Paper Alert – Salvus User 📢 Complex Martinique Intermediate-Depth Earthquake Reactivates Early Atlantic Break-Up Structures  https://lnkd.in/dYzRe3EM    Compound earthquakes that rupture several faults are frequently observed within the shallow lithosphere (< 70 km depth) but are much more difficult to observe for intermediate-depth events (70 – 300 km depth). Such observations are even more challenging in locations with sparse seismic networks.    This study combines multiple different types of data and methods to analyse the 2007 magnitude 7.4 Martinique earthquake, revealing that the event likely re-activated a fossil ridge-transform structure. Salvus is used to simulate Green’s Functions using a recent 3D seismic velocity model, in order to improve the accuracy of the moment tensor solutions.    Figure: Overview of regional 3D full waveform inversion. Source mechanisms A-C correspond to a single fault assumption, and D-F to a doublet assumption – each a weighted assumption of the corresponding orange and green double couple mechanisms. Displayed waveform fits are the result of experiment F in respective colours.    Image source: Figure 3 from the paper; published under CC BY 4.0 https://lnkd.in/e365Whs    Disclaimer: This work was carried out by researchers from Karlsruhe Institute of Technology (KIT), University of East Anglia and Imperial College London. Mondaic was not directly involved in this research, but we are proud to see #Salvus being used in such an exciting project.    #FWI #earthquake  

Abnormal low-magnitude seismicity preceding large-magnitude earthquakes. Abstract :"Unraveling the precursory signals of potentially destructive earthquakes is crucial to understand the Earth’s crust dynamics and to provide reliable seismic warnings. Earthquake precursors are ambiguous, but recent experimental studies suggest that robust warning signs may precede large seismic events in the short (day-to-months) term. Here, we show that the M6.4-M7.1 2019 Ridgecrest sequence (California) and the M7.1 2018 Anchorage earthquake (Alaska) were preceded by up to ~3 months of tectonic unrest on regional scales, as evidenced by abnormal low-magnitude seismicity spreading over the ~15-25% of Southern California and Southcentral Alaska. This precursory unrest has been discovered with an algorithm that integrates an innovative random forest machine learning approach and statistical features built from earthquake catalogs. Supported by a novel suite of finite element solid mechanics models, we propose that precursory, abnormal, low-magnitude seismicity arises if the pore fluid pressure within large fault segments escalates significantly as they approach failure, which leads to major uneven changes in the regional stress field. Our findings and method may open up new perspectives for surveillance agencies to anticipate when a region approaches an earthquake of great magnitude weeks to months before it occurs." https://lnkd.in/eVRQx6HB Társilo Girona 1 & Kyriaki Drymoni 2 1 Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA. 2 Earth and Environmental Sciences, Ludwig-Maximilians-Universität in Munich, Munich, Germany.

Are these two earthquakes identical or not? Bonatis et al. examine the subtle differences within the recent aftershock sequences of two moderate (Mw5.3 and Mw5.4) earthquakes that occurred in the same area of the North Aegean Trough. Read now:  https://lnkd.in/dxhY_ef9 On September 26, 2020, and January 16, 2022, the North Aegean Sea area, just south of Chalkidiki peninsula, experienced two notable (Mw5.3 and Mw5.4) earthquakes. Given their proximity to each other in both time and space, and considering such moderate-sized earthquakes are rare in this area, it's essential to delve into their characteristics to grasp the underlying geological processes better. Bonatis et al. used data from nearby seismic stations to refine their earthquake catalog and conducted a detailed analysis of both aftershock sequences. Their findings suggest these earthquakes do not stem from the primary geological structure known as the North Aegean Trough, but from lesser-known faults nearby, which are often associated with such complex tectonic environments. #Seismology #EarthquakeScience #peerreviewed #DiamondOpenAccess #Earthquake #OpenAccess #OpenScience #greece

Earthquake prediction in ITALY Earth-Science Reviews 69 (2005) 97–132 The Italian territory has been the object of several studies devoted to the analysis of seismicity and to earthquake precursors’ research. In this paper, we review the application to the Italian territory of two formally defined intermediate-term middle-range earthquake prediction algorithms, namely CN and M8S. The general methodology common to the two different algorithms makes use of general concepts of pattern recognition that permit to deal with multiple sets of seismic precursors, and allows for a systematic monitoring of seismicity, as well as for a widespread testing of the prediction performances. Italy represents the only region of moderate seismic activity where the M8S and CN algorithms are applied simultaneously for routine monitoring. Significant efforts have been made to minimize the intrinsic space uncertainty of predictions and the subjectivity of the definition of the areas where precursors should be identified. Several experiments have been dedicated to assess the robustness of the methodology against the unavoidable uncertainties in the data. With these results acquired, starting in July 2003, an experiment was launched for the real-time test of M8S and CN predictions.

NATURAL HAZARDS #Citizen #seismology helps decipher the 2021 Haiti earthquake  A network of citizen seismometers installed in 2019 provided near-field data critical to rapidly understand the mechanism of the mainshock and monitor its aftershock sequence. Their real-time data define two aftershock clusters that coincide with two areas of coseismic slip derived from inversions of conventional seismological and geodetic data. Machine learning applied to data from the citizen seismometer closest to the mainshock allows us to forecast aftershocks as accurately as with the network-derived catalog. This shows the utility of citizen science contributing to the understanding of a major earthquake. https://lnkd.in/gbD9UKRt

Creating an earthquake early warning system for Alaska is a big challenge. But it’s a challenge that geophysics research student Alexander Fozkos and colleagues at the Alaska Earthquake Center at the University of Alaska Fairbanks Geophysical Institute have accepted. Fozkos gave an update in a talk this morning at the Seismological Society of America annual meeting in Anchorage. Today is the last day of the weeklong meeting. The goal of the work by Fozkos and colleagues is to begin envisioning how, and how well, early warning might function in Alaska. To be clear: This is not an effort to predict an earthquake. Rather, it is an effort to provide some warning before a quake’s seismic waves reach a populated area. Fozkos detailed some of the work, including results of various scenarios. Conservative results suggest the potential for timely warning for shallow earthquakes for ground motions up to intensity VI, which is described as strong shaking that can move heavy furniture. The presentation was part of a session titled End-to-End Advancements in Earthquake Early Warning Systems.” #AECscience #ak_ssa #SSA2024

Aguilar Suarez & Beroza present a dataset of 1.6 million waveforms, to be used for machine-learning models in regional seismic event monitoring. Read more and get the dataset:  https://lnkd.in/eHGr8VJB The Curated Regional Earthquake Waveforms (CREW) seismic waveform dataset compiled and curated by Aguilar Suarez & Beroza, features labeled seismic wave arrivals at regional distances, where seismic waves are complex because they interact strongly with crust and upper mantle structure. This CREW dataset includes 1.6 million waveforms with global coverage that are intended to be used to develop and test machine learning models for the analysis of seismic events recorded at regional distances. #Seismology #EarthquakeScience #machinelearning #waveforms #seismicmonitoring #peerreviewed #DiamondOpenAccess #Earthquake #OpenAccess #OpenScience