This article describes a database that provides various catalogs of slow earthquakes. The catalogs list the times and the locations of the events, with additional information depending on the catalog. Because these catalogs are provided by a variety of documents in different formats, previous studies that use them must repeat complex procedures for preparing data. To make it more convenient to use multiple catalogs and promote research on slow earthquakes, we compiled a number of catalogs into a standardized format in a single repository, the Slow Earthquake Database, at the University of Tokyo (see Data and Resources). Users can visualize the source locations of multiple slow earthquakes in the database in map views on the website. Convenient access to the database encourages researchers to work on slow earthquakes regardless of their backgrounds. We also expect the database will foster collaboration among researchers in various fields and further the understanding of the mechanisms, environmental conditions, and underlying physics of slow earthquakes. Through the compilation of this database, we established a global standard of slow earthquake catalogs.

A large eruption occurred on Jan. 15, 2022, at the submarine volcano Hunga Tonga-Hunga Ha’apai, southern Pacific, and the atmospheric Lamb wave was observed to have traveled round the Earth multiple times with a speed of ~ 0.3 km/s. Here, I compare their ionospheric and atmospheric signatures using data from dense arrays of barometers and GNSS stations in Japan. I confirmed that the ionospheric disturbances passed over Japan at least four times, first from SE to NW, then from NW to SE, again from SE to NW, and finally from NW to SE. The propagation velocity of the ionospheric disturbances was as fast as the atmospheric Lamb wave, suggesting their origin as upward energy leakage from the troposphere. The first passage of the ionospheric disturbance started prior to the arrival of the Lamb pulse, but its physical mechanism is yet to be explored. Unlike the barometric records, waveforms and amplitudes of ionospheric disturbances exhibit large diversity along the wavefront, suggesting their turbulent nature. Graphical Abstract

Using ionospheric total electron contents residual data from 146 Global Navigation Satellite System stations in South America, we conducted three‐dimensional tomography of ionospheric electron density anomalies immediately before the 2015 Illapel M _w 8.3 earthquake, Central Chile. We used five GPS and five GLONASS satellites and applied continuity constraints to regularize the linear least squares inversion. The reconstructed anomalies are composed of positive and negative regions, at altitudes of ~200 km and ~400 km, respectively, distributed roughly along the geomagnetic field. This feature suggests that the observed anomalies occurred by the downward E  ×  B drift of electrons due to electric fields within ionosphere, possibly caused by surface positive electric charges. We also discuss the existence of the mirror image anomalies near the geomagnetic conjugate point of the epicenter using stations in Colombia.

High-Asia glaciers have been observed to be retreating the fastest in the southeastern Tibet Plateau (SETP), where vast numbers of glaciers and amounts of snow feed the streamflow of the Brahmaputra, a transboundary river linking the world's two most populous countries, China and India. However, the low temporal resolutions in previous observations of glacier and snow (GS) mass balance obscured the seasonal accumulation–ablation variations, and their modelling estimates were divergent. Here we use monthly satellite gravimetry observations from August 2002 to June 2017 to estimate GS mass variation in the SETP. We find that the “spring-accumulation-type” glaciers and snow in the SETP reach their maximum in May. This is in stark contrast to seasonal variations in terrestrial water storage, which is controlled by summer precipitation and reaches the maximum in August. These two seasonal variations are mutually orthogonal and can be easily separated in time-variable gravity observations. Our GS mass balance results show a long-term trend of $-\mathrm{6.5}\pm \mathrm{0.8}$ Gt yr⁻¹ (or 0.67±0.08 m w.e. yr⁻¹) and annual mass decreases ranging from −49.3 to −78.3 Gt with an average of $-\mathrm{64.5}\pm \mathrm{8.9}$ Gt in the SETP between August 2002 and June 2017. The contribution of summer meltwater to the Brahmaputra streamflow is estimated to be 51±9 Gt. This result could help to resolve previous divergent modelling estimates and underlines the importance of meltwater to the Brahmaputra streamflow. The high sensitivity between GS melting and temperature on both annual and monthly scales suggests that the Brahmaputra will suffer from not only changes in total annual discharge but also an earlier runoff peak due to ongoing global warming.