Live Earthquake Tracker

Global activity this week

Aggregate analysis of the past 7 days, followed by narrative reports on the week's significant events.

How earthquake data is measured

The three numbers you see next to every event on this site — magnitude, depth, and shaking intensity — each capture a different physical quantity. Knowing what each one is (and is not) makes the difference between reading the map and understanding what the map is telling you.

Magnitude: the energy at the source

Magnitude quantifies the total energy released by the earthquake at the fault rupture, as a single number. Modern magnitudes above roughly M4 are reported on the moment magnitude scale (Mw or Mww), which is calibrated against fault-area and slip measurements rather than simple amplitude readings. Because the scale is logarithmic, each whole-number step represents a thirty-two-fold increase in energy release: an M6 releases about 32 times more energy than an M5, and 1,000 times more than an M4. The seemingly small gap between M5.5 and M6.5 is the difference between a window-rattling local quake and a regional disaster. Our article on how modern magnitude is calculated walks through why older scales (Richter, mb, ML) were replaced for larger events.

Depth: where the rupture started

Every earthquake has both an epicenter (the point on the surface directly above the rupture) and a hypocenter (the 3D point in the crust or mantle where the rupture nucleated). Depth is the vertical coordinate of the hypocenter, reported in kilometers. The USGS groups depths into three bands: shallow (less than 70 km), intermediate (70–300 km), and deep-focus (greater than 300 km). Shallow events are by far the most numerous and are responsible for nearly all earthquake damage on land, because their seismic waves have less rock to attenuate on the way to the surface. Deep-focus events, some as deep as 700 km, almost always occur inside descending subduction slabs and rarely cause strong surface shaking. More on the distinction between shallow and deep-focus earthquakes.

Intensity: what the ground actually did

Where magnitude is one number per earthquake, intensity is a map — a different value for every location where the shaking was recorded or reported. The USGS uses the Modified Mercalli scale (MMI) I through X+, with descriptive anchors like "weak", "moderate", "strong", and "severe". MMI is derived from peak ground acceleration, peak ground velocity, and crowd-sourced felt reports submitted to the Did You Feel It? system. A headline number like "M7.1" describes the source; a ShakeMap showing MMI VIII in one neighborhood and MMI IV a few kilometers away describes how the crust, soil, and distance from the rupture shaped what people actually felt. When reviewing an event, always look at both — magnitude tells you how big it was, intensity tells you how it landed.

Where earthquakes happen, and why

The global map of earthquake epicenters is not random. Plot ten thousand events and the outlines of Earth's tectonic plates emerge — virtually all seismicity is concentrated along the boundaries where plates converge, diverge, or slide past one another. Understanding plate boundary stress accumulation is the single most useful frame for reading our maps.

The Pacific Ring of Fire

About 80% of the world's largest earthquakes, and nearly all of the world's deep-focus events, originate along the 40,000-kilometer loop of subduction zones ringing the Pacific. This includes the coasts of Japan, Indonesia, the Philippines, Alaska, Chile, Peru, and New Zealand. These zones produce both frequent shallow thrust earthquakes at the subduction interface and sparse but very large intermediate-depth events inside the downgoing slab.

The Alpine–Himalayan belt

Running from the Mediterranean through Türkiye, the Caucasus, Iran, and into the Himalayas and Myanmar, this continental-collision belt is responsible for roughly 15% of global seismicity. The February 2023 Türkiye–Syria sequence and the historical Himalayan megathrusts beneath Nepal and northern India are the canonical examples. Because these earthquakes occur within continental crust where millions of people live, their impact per unit magnitude is often disproportionate.

Mid-ocean ridges, transform faults, and intraplate zones

The global mid-ocean ridge system — a 65,000 km submarine mountain range where plates diverge — produces a steady stream of small-to-moderate earthquakes, almost all offshore and rarely felt. Transform boundaries like California's San Andreas Fault or New Zealand's Alpine Fault generate large strike-slip events that can reach magnitude 8 but typically do not trigger tsunamis. Finally, a small but consequential fraction of earthquakes occur far from any active plate boundary — intraplate events like the 1811–12 New Madrid sequence or Australia's 2016 Petermann earthquake. These are poorly understood, rare, and often catch populations that have not prepared for seismic risk.

Frequently asked questions