Earthquakes and viral epidemics spread are totally different events, but under rare circumstances they could strike at the same time. At midnight on 3 February 2020, a magnitude 5.1 earthquake occurred near Chengdu, the capital of Sichuan Province in China. This event was unique because it occurred during the outbreak of a new coronavirus known as the severe acute respiratory syndrome coronavirus 2

The topic of earthquake prediction has a long history, littered with failed attempts. Part of the challenge is that possible precursory signals are usually reported after the event, and the systematic relationships between potential precursors and main events, should they exist, are unclear. Several recent studies have shown the potential of new approaches to simultaneously detect earthquake foreshocks

Accurate monitoring of volcanic activity demands expertise in fields including geophysics, geology, and geochemistry. Data obtained from the most recent technical advances are particularly vital in pre‐eruptive phases. In particular, seismic monitoring in near real time is essential to locating and discriminating early signs among different sources of seismic waves, especially those related to movement

The accuracy of preinstrumental earthquake data, which cover longer time periods than instrumental recordings, and a more widespread assessment of macroseismic intensity data have significantly improved the knowledge of the seismic behavior of many regions of the world. The importance of these data is now widely recognized, and such an awareness stemmed from the realization that even though instrumental

Archives and libraries were visited to find previously unknown documents testifying to the Lurøy, Norway, earthquake of 31 August 1819 in northernmost continental Europe. The focus here is on Sweden, Finland, and Russia, which are important for determining the area of perceptibility east of Norway. The new written sources include 12 notes or entries in original archived documents, six contemporary

The continental part of west‐central Mexico is characterized by the active extensional tectonic regimes of the Trans‐Mexican volcanic belt and the adjacent southern Basin and Range Province. The deformation of the latter is distributed over several topographically very pronounced grabens and half‐grabens (width 10–20 km, length ≤200 km⁠; throw 1–2 km), including the Aguascalientes, Juchipila, Tlaltenango

Information about historical earthquakes in the Iberian Peninsula going back to Antiquity (Roman times) can be found in different types of documents, such as unpublished contemporary manuscripts preserved in archives, general, and regional histories in Spain and Portugal, published documents and reports on the damage of specific earthquakes, and reports in newspapers and magazines. The 1755 Lisbon

In 4 August 1885, 06:30 local time, a strong earthquake (reported intensities up to VI–VII modified Mercalli intensity [MMI]) was felt in the French Guiana, causing slight damage. Recently discovered newspaper records show that this event was also felt as far as Georgetown (British Guyana), Belém, and several other localities along the Amazon River toward Manaus (Brazil). The distribution of intensities

The 1703 Mw 6.9 seismic sequence (⁠I0 11 Mercalli–Cancani–Sieberg scale) was one of the most important crises ever occurred in Italy and has left a deep mark on the seismic history of cities and towns of central Italy. Abundant documents testify the damage suffered by the city of Rome during this sequence; however, the descriptions are mainly referred to monumental buildings. For the recent macroseismic

This article presents a tool to quantify uncertainties in magnitude–depth (⁠M‐H⁠) estimates for earthquakes associated with macroseismic intensity data. The tool is an open‐source code written in Python and is named quantifying uncertainties in earthquakes’ magnitude and depth (QUake‐MD). In QUake‐MD, uncertainties are propagated from the individual intensity data point (IDP) to the final magnitude

Seismic hazard in the southern Malay Peninsula located within the Sundaland block in Southeast Asia is poorly understood. The paucity of historical earthquakes and low‐magnitude instrumented seismicity has led to the assumption that this region is largely aseismic. We question this point of view by reassessing historical seismicity in this region and, in particular, a pair of moderate earthquakes in

In current catalogs, the parameters of preinstrumental earthquakes represent the final synthesis of earthquake records of very different type, quality, and reliability. Parameters may be derived from actual and contemporary observations of earthquake effects interpreted as intensity distributions or may be supplied by later seismological studies and descriptive catalogs, consisting of the reinterpretation

The seven islands of Corfu, Paxoi, Kephalonia, Ithaca, Lefkada, Zakynthos, and Cythera (Ionian Sea, offshore western Greece) were a British protectorate with the name of “United States of the Ionian Islands” between 1815 and 1864. Although many earthquake studies have already examined the past seismicity of this area, they contain only a few data for a handful of earthquakes, for an area known to be

The 6 February 1971 Tuscania (central Italy) earthquake belongs to a peculiar family of destructive seismic events that have occurred in an area classified as low‐seismic hazard, causing heavy damage and tens of casualties. However, this earthquake took place at the dawn of modern seismology in Italy and is far from being fully characterized from an instrumental and macroseismological point of view

To know the Ancient and Medieval events and the recurrence interval of the great Kanto earthquakes such as the 1923 and 1703 ones generated by the subduction of the Philippine Sea plate along the Sagami trough, central Japan, I examined the latest dataset of historical records. I used only rank‐A (contemporary) materials in the Online Database of Historical Documents on Japanese Earthquakes and Eruptions

Contemporary Ottoman sources bring a major contribution to the description of the seismic activity in the eastern Mediterranean region and are extensively used by historical seismologists. Among these, the documents of the Ottoman State Archives (Istanbul), and more specifically the correspondence of the local governors with the central authorities form a valuable source for the description of the

Long‐term seismicity in a certain region can be estimated from the number of felt earthquakes obtained from seismic intensity measurements or historical documents. To obtain a homogeneous estimate, continuous records with a uniform detection threshold are required. Seismic intensity data in Tokyo, which are measured by professional observers and archived by the Japan Meteorological Agency (JMA) since

Earthquakes produce effects on the built and natural environment, the severity of which decays with distance from the epicenter. Empirical relations describing the intensity attenuation with distance are fundamental for seismic hazard assessment and for deriving parameters for preinstrumental events. Seismic intensity is usually assigned based on damage to buildings and infrastructures; this can be

We estimated the origin time of the 1854 Ansei–Tokai tsunami from the tsunami waveforms recorded at three tide gauge stations (Astoria, San Francisco, and San Diego) on the west coast of North America. The tsunami signal is apparent in the San Francisco and San Diego records, and the arrival time was 0–1 p.m. Greenwich Mean Time (GMT) on 23 December 1854, whereas the tsunami signal of Astoria is ambiguous

Historical seismic intensity data are useful for myriad reasons, including assessment of the performance of probabilistic seismic hazard assessment (PSHA) models and corresponding hazard maps by comparing their predictions to a dataset of historically observed intensities in the region. To assess PSHA models for California, a long and consistently interpreted intensity record is needed. For this purpose

Yunnan Province is in southwest China, where the seismicity has been active since ancient times. Generally, the uncertainty of historical earthquake parameters is larger. To amend the parameters of historical earthquakes, we have developed a new intensity attenuation equation. From 2000 to 2018, there were 25 instrumentally recorded earthquakes with Ms 5.0–6.6 in Yunnan. The parameters of those earthquake

Ammianus Marcellinus, a fourth‐century writer, reported that after an earthquake, on 21 July 365, the sea retreated and then flooded numerous coasts, among them Alexandria (Egypt) and Methoni (southwest Greece). Several other ancient authors seem to mention this event as a “universal earthquake.” The inferred tsunami is usually assigned to reactivation of a fault in the Hellenic (Aegean) Arc, derived

The 10 July 1804 Kisakata earthquake occurred offshore Kisakata (Akita, Japan), and widespread felt shaking was reported from Matsumae (Hokkaido) to Ohmi‐Hachiman (Shiga Prefecture). The earthquake caused strong ground motions that extensively damaged areas near the epicenter, such as along the coast of Kisakata, and the resultant tsunami caused extensive damage along the coast from Kisakata to Sakata

In ancient China, the government annals provided abundant historical earthquake records, which lasted more than 2000 yr. In some cases, the earthquake damage descriptions from the high‐tier government annals are so concise that the specific place names were omitted, even the names of towns where the damage might have actually occurred. The intensity data point (IDP) was assigned to the capital town

For historical earthquakes, the spatial distributions of macroseismic intensity reports are commonly used to estimate the event locations. The methods to locate historical earthquakes assume that the highest seismic intensity shows the best estimate of the location of the earthquake. Uncertainties in the locations estimated from macroseismic data can be due to an uneven geographic distribution of sites

Rescue work involving scanning and digitization research on historical analog seismograms nationwide in China was launched in 2017. A series of results have been accomplished. There are more than 13 million analog seismic records existing in China, and about 3 million of them were scanned by December 2019. The Second Monitoring and Application Center of China Earthquake Administration completed the

The recent development of advanced seismograph networks offers us a chance to remotely detect landslide occurrences with high‐frequency (⁠>∼1 Hz⁠) components. This study examined a landslide in central Japan that produced clearly detectable seismic signals at multiple seismic stations in a permanent network. Wave packets propagated with a group velocity of 3 km/s from the landslide area. Using a source

The injection of water into geothermal systems is an important procedure required to recover subsurface water resources and enhance permeability for increasing the reservoir volume. The injected water often leads to microseismic events during migration, which can be used to directly track the location of the injected water. However, in rare cases, unexpectedly large induced seismicity occurs after

The number of earthquakes in the western Canada sedimentary basin (WCSB) has increased drastically in the last decade related to unconventional energy production. The majority of reported earthquakes are correlated spatially and temporally with hydraulic fracturing (HF) well stimulation. In this study, we use waveform data from a new deployment of 15 broadband seismic stations in a spatial area of

Seismic noise with frequencies above 1 Hz is often called “cultural noise” and is generally correlated quite well with human activities. Recently, cities in mainland China and Italy imposed restrictions on travel and day‐to‐day activity in response to COVID‐19, which gave us an unprecedented opportunity to study the relationship between seismic noise above 1 Hz and human activities. Using seismic records

The task of seismic phase association is to correlate the onsets of radiated seismic energy with an underlying source. Commonly applied within seismic monitoring networks for event detection, it forms a vital component of many seismic processing pipelines. With the complexity of this task naturally increasing with the number of phases to simultaneously correlate, rapid advancements in the number of

We constrain D″ anisotropy beneath the North American continent and northeastern Pacific using two approaches: (1) joint splitting analysis of SKS and SKKS phase pair for a common event, in which we obtain 158 pairs exhibiting discrepant splitting results and 791 pairs nondiscrepant splitting results; and (2) group splitting analysis of SKS (or SKKS) phase from neighboring events recorded at a common

Ambient‐noise tomography (ANT) has become an effective method for determining the fine velocity structure of the shallow crust. However, studies on metal mines using this method are rarely reported. To investigate the tectonic background and prospecting of the deep mine in the Baiyun gold deposit (BYGD) of eastern Liaoning Province, China, we use ANT to determine a 3D S‐wave velocity structure model

The ambient seismic field is now routinely used for imaging and monitoring purposes. Most commonly, applications aim at resolving crustal‐scale features and utilize ocean‐generated surface waves. At smaller scales and at frequencies above the microseismic peaks, local sources of seismic energy, often anthropogenic, are dominant, and understanding of their contributions to the ambient seismic field

We investigate the potential of using borehole strainmeter data from the Network of the Americas (NOTA) and the U.S. Geological Survey networks to estimate earthquake moment magnitudes for earthquake early warning (EEW) applications. We derive an empirical equation relating peak dynamic strain, earthquake moment magnitude, and hypocentral distance, and investigate the effects of different types of

The Mw 7.1 Ridgecrest earthquake sequence in California in July 2019 offered an opportunity to evaluate in near‐real time the temporal and spatial variations in the average earthquake size distribution (the b‐value) and the performance of the newly introduced foreshock traffic‐light system. In normally decaying aftershock sequences, in the past studies, the b‐value of the aftershocks was found, on

Recognizing earthquakes as foreshocks in real time would provide a valuable forecasting capability. In a recent study, Gulia and Wiemer (2019) proposed a traffic‐light system that relies on abrupt changes in b‐values relative to background values. The approach utilizes high‐resolution earthquake catalogs to monitor localized regions around the largest events and distinguish foreshock sequences (reduced

We propose a method of real‐time tsunami detection using ensemble empirical mode decomposition (EEMD). EEMD decomposes the time series into a set of intrinsic mode functions adaptively. The tsunami signals of ocean‐bottom pressure gauges (OBPGs) are automatically separated from the tidal signals, seismic signals, as well as background noise. Unlike the traditional tsunami detection methods, our algorithm

We propose a new automated procedure for using continuous seismic waveforms recorded by a dense array and its nearby regional stations for P‐wave arrival identification, location, and magnitude estimation of small earthquakes. The method is illustrated with a one‐day waveform dataset recorded by a dense array with 99 sensors near Anza, California, and 24 surrounding regional stations within 50 km of

Inertial sensors like seismometers or accelerometers are sensitive to tilt motions. In general, from pure acceleration measurements, it is not possible to separate the tilt acceleration from the translational ground acceleration. This can lead to severe misinterpretation of seismograms. Here, we present three different methods that can help solving this problem by correcting translational records for

We introduce FD3D_TSN—an open‐source Fortran code for 3D dynamic earthquake rupture modeling based on the staggered grid fourth‐order finite‐difference method employing a regular cubical spatial discretization. Slip‐weakening and fast‐velocity‐weakening rate‐and‐state fault friction laws are combined with vertical planar fault geometry, orthogonal to a planar free surface. FD3D_TSN demonstrates good

We exploit estimates of P‐wave reflectivity from autocorrelation of transmitted teleseismic P arrivals and their coda in a common reflection point (CRP) migration technique. The approach employs the same portion of the vertical‐component seismogram, as in standard Ps receiver function analysis. This CRP prestack depth migration approach has the potential to image lithospheric structures on scales as

The U.S. Geological Survey Earthquake Hazards Program has overall successfully fulfilled its mission of providing timely earthquake information via web applications and other methods. Imagine a single month of earthquake data delivery, serving 3.6 billion total data requests, including 29 million pageviews by 7.1 million users, 606 million automated data feeds, and 45 million catalog downloads. Yet

The Mexican National Seismological Service (SSN) was founded on 5 September 1910, in response to commitments made by Mexico to the International Association of Seismology in 1903. The first seismic instruments installed in 1904 were a Bosch–Omori seismograph and a Palmieri seismoscope. The SSN was formally inaugurated on 5 September 1910, a few days before the revolution broke out; a political struggle

The 2 February 1816 North Atlantic earthquake is virtually unknown to the international scientific community, and the few existing studies—solely based on two or three macroseismic intensities—pointed to a magnitude near 7 and a location at the eastern end of the Gloria fault in the Azores‐Gibraltar Fracture Zone (AGFZ). Through careful search, we discovered more than 40 independent macroseismic observations

The Incorporated Research Institutions for Seismology Earthquake Browser (IEB; see Data and Resources) is a web‐based tool that enables anyone to query an earthquake database composed of over five million events recorded over the past 50 yr. The IEB visitor can query on earthquake magnitude, depth, timing, and location and can visually display the results in 2D map view or as an interactive pseudo

A temporary seismometer vault was buried by a moving sand dune in the Taklimakan Desert at northwestern China in October 2019. The dune gradually covered the solar panel and the power supply to the seismic station was subsequently cut off. Here, we show that the burial process can be diagnosed according to the temperature record from the thermometer in the data‐logger, an ultra‐low‐frequency seismic

The Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence occurred on 4 and 5 July 2019 within the eastern California shear zone of southern California. Both events produced extensive surface faulting and ground deformation within Indian Wells Valley and Searles Valley. In the weeks following the earthquakes, more than six dozen scientists from government, academia, and the private sector carefully documented

The eastern margin of North America has undergone multiple episodes of orogenesis and rifting, yielding the surface geology and topography visible today. It is poorly known how the crust and mantle lithosphere have responded to these tectonic forces, and how geologic units preserved at the surface related to deeper structures. The eastern North American margin has undergone significant postrift evolution

The eastern margin of North America has been affected by a range of fundamental tectonic processes in the geologic past. Major events include the Paleozoic Appalachian orogeny, which culminated in the formation of the supercontinent Pangea, and the breakup of Pangea during the Mesozoic. The southern New England Appalachians exhibit a particularly rich set of geologic and tectonic structures that reflect

The 2020 Annual Meeting of the Seismological Society of America (SSA), which was scheduled for 28–30 April 2020 in Albuquerque, New Mexico, was not held this year due to health and safety concerns related to the coronavirus disease (COVID‐19) pandemic. The SSA Board of Directors’ decision not to host the meeting, a first in the Society’s 114 yr history, was guided by a desire to protect its members

Some disasters with serious consequences do not occur unexpectedly, just rarely, and hit suddenly with little or no warning. With respect to natural hazards, earthquakes share these characteristics, being the deadliest of natural hazards. Catastrophic earthquakes impact large areas and sometimes affect millions of people (Munich RE, 2015; Wallemacq and House, 2018). Even with elaborate crisis‐management

The Coulomb stress theory is the basic physics principle upon which scientists rely for improving our understanding behind earthquake triggering processes and, therefore, our predictability of future earthquake hazards. The assumption that following a large earthquake the expected regional stress redistribution will affect other faults has been known since the late nineteenth century and has been passed

On 4 July 2019 southern California was rattled by the largest earthquake to occur in the region in nearly 20 yr, a moment magnitude (⁠MW⁠) 6.4 earthquake that occurred near Ridgecrest approximately 200 km north of Los Angeles. It was followed on 6 July by a larger MW 7.1 earthquake. The distribution of aftershocks made it clear from the beginning that this was a complex earthquake sequence involving

Traditional real‐time (RT) seismology has relied on inertial sensors to characterize ground motions and earthquake sources, particularly for hazards applications such as warning systems. In the past decade, a revolution in high‐rate, RT Global Navigation Satellite Systems (GNSS) displacement has provided a new source of data to augment traditional measurement devices. The Ridgecrest, California, earthquake

Rapid seismic deployments following large earthquakes capture ephemeral near‐field recordings of aftershocks and ambient noise that can provide valuable data for seismological studies. The U.S. Geological Survey installed 19 temporary seismic stations following the 4 July 2019 Mw 6.4 and 6 July 2019 (UTC) Mw 7.1 earthquakes near the city of Ridgecrest, California. The stations record the aftershock

The 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence occurred in the eastern California shear zone (ECSZ). The mainshock ruptured the Little Lake fault zone, and aftershocks extended from the Garlock fault in the south to the southern end of the 1872 M 7.5 Owens Valley earthquake rupture in the north. We present data from the Southern California Seismic Network (SCSN) and partner seismic networks

I use template matching and precise relative relocation techniques to develop a high‐resolution earthquake catalog for the initial portion of the 2019 Ridgecrest earthquake sequence, from 4 to 16 July, encompassing the foreshock sequence and the first 10+ days of aftershocks following the Mw 7.1 mainshock. Using 13,525 routinely cataloged events as waveform templates, I detect and precisely locate

Interferometric Synthetic Aperture Radar is an important tool for imaging surface deformation from large continental earthquakes. Here, we present maps of coseismic displacement and strain from the 2019 Ridgecrest earthquakes using multiple Sentinel‐1 images. We provide three types of interferometric products. (1) Standard interferograms from two look directions provide an overview of the deformation

On 4 July 2019, the Ridgecrest earthquake sequence began with a series of foreshocks including an Mw 6.4 event near Searles Valley, California. This was then followed 34 hr later by an Mw 7.1 mainshock located just 15 km to the north, with the earthquake sequence resulting in a complex array of intersecting faults. This earthquake sequence poses several interesting questions including, did the stress